22nd young atom opticians conference 2016 · young atom opticians conference 22 nd young atom...

22nd

Young Atom Opticiansconference

22nd


YAO 2016

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YAO 201622nd


Munich and Garching, GermanyFebruary 22-26, 2016

OFFICIAL PROGRAMME

Cover illustration: Martin Ibrügger and Alexander PrehnPhotography of optical resonator: Christian Sames

Garching, February 2016

Welcome to YAO 2016!

For 22 years now the Young Atom Opticians conference is hosted in places all overEurope and gathers young scientists in the field of atomic, molecular and optical physicsfrom all over the world. For many scientists it has been the first conference in theirscientific career and many of them are well known in the field today.

After this long tradition we, the Quantum Dynamics group of the Max Planck Instituteof Quantum Optics, are happy to welcome you here in Munich at the YAO 2016. Wehope that you can use this experience to find your way into the scientific world, establishcontacts with other young scientists or extend your view over the field.

The scientific program covers 5 invited talks by leading scientists of their fields, 41 talksby young scientists, 2 poster sessions and a tour through some of our institute’s labs.

Beyond that the Welcome Reception and the Conference Dinner will give you the possi-bility to get to know new people and discuss, if you like, even non-physics topics.

We wish you an interesting conference and a good time in Munich.

Your organisation committee

Thomas Gantner, Bastian Hacker, Martin Ibrügger, Matthias Körber, Alexander Prehn,Steffen Schmidt, and Stephan Welte

Table of contents

Conference schedule 9

Talks 16

Monday, February 22 16

Tuesday, February 23 28

Wednesday, February 24 40

Thursday, February 25 52

Friday, February 26 62

Posters 71

Session A 71

Session B 98

Additional information 124

Talks and poster presentations 124

Hotel Ibis München City Nord 125

The Garching campus 126

Conference venue and lunch 127

Wifi 128

Social events 129

Munich during the day 131

Munich at night 132

Public transport 134

Index of participants 136

Committee 140

About YAO 141

Sponsors 142

7

Sche

dule

Conference schedule

Sunday, February 21

5:00 pm Registration desk, Hotel Ibis München City Nord

7:00 pm Welcome reception, Sponsored by Menlo SystemsVorhoelzer Forum at TUMArcisstraße 21, MunichPlease bring your name tag.

Monday, February 22

8:30 am Registration desk, IAS Foyer

9:15 am Organisation CommitteeWelcome note

9:30 am Gerhard Rempe, Max Planck Institute of Quantum OpticsCavity Quantum Electrodynamics: A Universal Quantum OpticsToolbox

10:30 am Coffee break, IAS Faculty Club

11:10 am Ultracold fermions, Chair: Frauke SeesselbergGiulia De Rosi, University of TrentoCollective oscillations of a trapped quantum gas in lowdimensions

9

S chedule

Ralf Klemt, University of HeidelbergAtom-Noise Correlations in an Ultracold Fermi Gas in a 2DOptical Lattice

Daniel Pecak, Polish Academy of SciencesTwo-flavour mixture of a few fermions of different mass in aone-dimensional harmonic trap

Jorge Yago, University of StrathclydeDissipative engineering of spin-entangled states in Fermi Gases

12:30 pm Lunch break, Canteen of IPP

2:00 pm Cavities, Chair: Julia BenedikterTom Barrett, University of OxfordDynamic control of on-demand single photons from a coupledatom-cavity system

Elisa Will, TU ViennaNonreciprocal light propagation based on chiral interaction oflight and matter

Orel Bechler, Weizmann Institute of ScienceExtraction of a Single Photon from an Optical Pulse

3:00 pm Coffee break, IAS Faculty Club

3:30 pm Warm atomic vapours, Chair: Thomas GantnerMichał Parniak, University of WarsawOpen-loop four-wave mixing as a light-atom interface

Michał Dabrowski, University of WarsawN-photon generator based on Raman quantum memory

5:00 pm Lab tours, Max Planck Institute of Quantum OpticsThe experimental divisions of the institute open their labs.Topics include: Precision spectroscopy of hydrogen, Cavity QEDwith single atoms, Rydberg Atoms, Ultracold bosons andfermions, Quantum simulation, Cold and ultracold molecules,Ultrashort laser pulses.

10

Sche

dule

Tuesday, February 23

9:30 am Francesca Ferlaino, University of InnsbruckThe Fascination of Lanthanides for Ultracold Quantum Physics


11:10 am Lattice Physics, Chair: Bastian HackerChristian Baals, TU KaiserslauternStudying quench dynamics in an ultracold quantum gas bynear-field interferometry

Rafał Ołdziejewski, Polish Academy of SciencesTwo dipolar atoms in a harmonic trap

Xavier Alauze, Observatoire de ParisA trapped atom interferometer for short range forcesmeasurement

Yijian Meng, TU ViennaMicrowave spectroscopy of nanofiber-trapped Cesium atoms


2:00 pm Ions, Chair: Nicolas TolazziSaravanan Sengottuvel, University of SiegenFeedback-based position stabilisation of microparticles

Iñigo Arrazola, University of the Basque CountryDigital-Analog Quantum Simulation of Spin Systems in TrappedIons

Xiao-Hang Cheng, University of the Basque CountryTime and Spatial Parity Operations with Trapped Ions


3:30 pm Ultracold Bosons in 1D, Chair: Martin IbrüggerFederica Cataldini, TU ViennaRelaxation dynamics of a one-dimensional Bose gas

Alexander Schnell, TU DresdenInducing Bose condensation with a hot needle

4:15 pm Poster Session A, IAS Faculty Club

11

S chedule

Wednesday, February 24

9:30 am Michael Fleischhauer, TU KaiserslauternMany-body correlations in open systems: Optically drivenRydberg gases


11:10 am Ultracold Bosons, Chair: Johannes ZeiherOttó Elíasson, Aarhus UniversityEnhanced quantum simulation of quantum phase transitionsusing non-destructive measurements

Marine Pigneur, TU ViennaTunneling dynamics of interacting Bose-Einstein condensates ina double-well potential

Maximilian Pruefer, University of HeidelbergNon-equilibrium quantum dynamics of unstable spinorBose-Einstein Condensates

Christoph Eigen, University of CambridgeCollapse Dynamics of an Attractive Bose-Einstein Condensate


2:30 pm Interference effects, Chair: Alexander PrehnLaure Chichet, Institut d’Optique d’AquitaineTesting the weak equivalence principle using a dual-species atominterferometer in microgravity

Christian Knobloch, University of ViennaChallenges in matter-wave diffraction of polarizable and polarmolecules at nanomechanical masks

Daniela Holzmann, University of InnsbruckCollective scattering and oscillation modes of optically boundpoint particles trapped in a single mode waveguide field


3:30 pm Experimental advances, Chair: Stephan WeltePhilip Ireland, University of St. AndrewsNew techniques for portable cold atom experiments

12

Sche

dule

Hector Mas, University of CreteState-dependent manipulation of ultra-cold atoms in a ringwaveguide: towards a matter-wave Sagnac interferometer

4:15 pm Poster Session B, IAS Faculty Club

13

S chedule

Thursday, February 25

9:30 am Immanuel Bloch, Max Planck Institute of Quantum OpticsControlling and Exploring Quantum Matter Using UltracoldAtoms in Optical Lattices


11:10 am Rydberg Physics, Chair: Daniel TiarksFrédéric Assémat, Collège de FranceQuantum Metrology with Schrödinger Cat States of a RydbergAtom

David Davtyan, University of AmsterdamA quantum platform using Rydberg atoms in magnetic lattices

Felix Engel, University of StuttgartRydberg Spectroscopy in a Bose-Einstein Condensate

Fabian Pokorny, Stockholm UniversityRydberg excitation of trapped strontium ions


2:00 pm Bosons in special potentials, Chair: Matthias KörberMartin Sturm, TU DarmstadtBottom-up approach to many-body physics with ultracold atomsin adjustable lattices

Jean-Loup Ville, Collège de FranceGeneration of highly tunable light potentials on atwo-dimensional degenerate Bose gas

Thomas J. Elliott, University of OxfordEngineering Many-Body Systems with Quantum Light Potentialsand Measurements

4:00 pm City tour Fischbrunnen, Marienplatz, Munich

7:30 pm Conference dinner: Augustiner KlosterwirtAugustinerstraße 1, MunichPlease bring your name tag.

14

Sche

dule

Friday, February 26

9:30 am Ed Hinds, Imperial College LondonTesting fundamental physics with cold atoms and molecules


11:10 am Ultracold Bosons, Chair: Steffen SchmidtMarco Gabbrielli, University of FlorenceSpin-Mixing Interferometry with Bose-Einstein Condensates

Andrea Invernizzi, Collège de FranceTwo steps condensation in a gas of spin-1 sodium atoms

Ryan Jones, University of NottinghamFar-field resonance fluorescence for a dipole-interacting atomicgas

Jay Man, University of CambridgeCold-collision shifts in a unitary Bose gas


2:00 pm Fundamental Physics, Chair: Jean-Loup VilleLorenzo Livi, European Laboratory for Non-LinearSpectroscopy (LENS)Observation of chiral edge states with neutral fermions insynthetic Hall ribbons

Vito Giovanni Lucivero, Institut de Ciencies Fotoniques(ICFO)Squeezed-light spin noise spectroscopy

Karsten Lange, University of HanoverSatisfying the Einstein-Podolsky-Rosen criterion with massiveparticles

3:00 pm Organisation committeeClosing remark

15

Monday

Talks: Monday, February 22

Gerhard Rempe, Max Planck Institute of Quantum OpticsGerhard Rempe is a German physicist, Director at theMax Planck Institute of Quantum Optics and Hono-rary Professor at the Technical University of Munich.He has performed pioneering experiments in atomicand molecular physics, quantum optics and quantuminformation processing. Gerhard Rempe studied mathe-matics and physics at the Universities of Essen andMunich between 1976 and 1982. In 1986 he receivedhis PhD degree at the Ludwig-Maximilians-Universityof Munich. The thesis was entitled “Investigation ofthe interaction of Rydberg atoms with radiation” andreports on experiments performed in the group of Her-bert Walther. In the same year he was awarded a first

job offer to a permanent position as a lecturer at the Free University of Amsterdamin the Netherlands. He remained in Munich and completed his habilitation in1990 with the thesis “Quantum effects in the one-atom maser”. From 1990 to1991 he was Lecturer and from 1990 to 1992 Robert Andrews Millikan Fellow atthe California Institute of Technology in Pasadena, California, USA. In 1992 heaccepted an appointment as professor of experimental physics at the University ofKonstanz. In 1999 he was appointed scientific member of the Max Planck Society,director at the Max Planck Institute of Quantum Optics and honorary professorat the Technical University of Munich.

16

Mon

day

Cavity Quantum Electrodynamics: A Universal QuantumOptics Toolbox

Gerhard Rempe1

1Max-Planck-Institut fur Quantenoptik,Hans-Kopfermann-Str.1, 85748 Garching, Germany

Electromagnetic resonators provide unparalleled possibilities in controlling the in-teraction between atoms and photons. The recently developed techniques forcontrolling also the position and the momentum of the atoms inside an optical res-onator now open up new experimental avenues for genuine quantum-mechanicalexperiments. These relate both to fundamental research and to the engineer-ing of quantum-information processing devices. Exciting possibilities concern, forexample, long-distance distributed quantum networking and scalable quantumcomputation. The talk will highlight some recent achievements here, like the firstnondestructive detection of an optical photon, the heralded and efficient storageof a flying optical quantum bit in a stationary atom, and the realization of quan-tum gates with individually addressable atomic and photonic quantum bits. Thetalk will also describe some very basic but surprisingly counterintuitive radiationphenomena that occur when the system size doubles from one atom to two atomscoupled to an optical resonator.

17

Monday

Collective oscillations of a trapped quantum gas in lowdimensions

Giulia De Rosi1, ∗ and Sandro Stringari1

1INO-CNR BEC Center and Dipartimento di Fisica,Universita di Trento, Via Sommarive 14, I-38123 Povo, Italy

We present a comprehensive study of the discretized modes of an atomic gas indifferent conditions of confinement. Starting from the equations of hydrodynamicswe derive a closed equation for the velocity field, depending on the adiabatic andisothermal compressibilities and applicable to different dimensions and quantumstatistics. At zero temperature the equation reproduces the irrotational behaviorof superfluid hydrodynamics. It is also applicable above the critical temperaturein the collisional regime, where the appearence of rotational components in thevelocity field is caused by the external potential. In the presence of harmonictrapping, a general class of analytic solutions is obtained for systems exhibiting apolytropic equation of state, characterized by a power law isoentropic dependenceof the pressure on the density. Explicit results for the compressional modes arederived for both Bose and Fermi gases in the pancake and cigar as well as in thedeep two- and one-dimensional regimes. Our results agree with the analyticalpredictions available in the literature in some limiting cases. They are particularlyrelevant in one-dimensional configurations, where the study of the collective fre-quencies could provide a unique test of the achievement of the collisional regimeat finite temperature [1].

[1] G. De Rosi and S. Stringari, arXiv:1507.07821, accepted for publication inPhys. Rev. A (2015).

∗ [email protected]

18

Mon

day

Atom-Noise Correlations in an Ultracold Fermi Gas in a 2DOptical Lattice

Ralf Klemt,1, ∗ Luca Bayha,1 Puneet Murthy,1 Mathias

Neidig,1 Martin Ries,1 Gerhard Zurn,1 and Selim Jochim1

1Physikalisches Instiut, Universitat HeidelbergIm Neuenheimer Feld 226, 69120 Heidelberg, Germany

In this talk we will present our current progress in investigating an ultracold,two-component 6Li Fermi gas in the BEC-BCS crossover, which is trapped in a2D optical lattice. By using a matterwave focusing technique, we measure themomentum distribution which allows access to spatial coherence information. Werealize both a transition from the normal to the superfluid phase and from thesuperfluid to an insulating phase by tuning the temperature and the lattice depth,respectively.For the insulating phase a loss of first-order correlations and phase coherenceis expected. Probing the type of this phase as well as observing spin-orderingrequires to measure second-order, i.e. atom-noise, correlations.Therefore, a spin resolved two-state imaging technique is implemented, whichallows to simultaneously measure the momentum space density profile of bothspin components. With this tool at hand the spatial atom-noise correlationsbetween the different spin components can be obtained in addition to single spincorrelations.

∗ [email protected]; http://ultracold.physi.uni-heidelberg.de

19

Monday

Two-flavour mixture of a few fermions of different mass in aone-dimensional harmonic trap

Daniel Pecak,1, ∗ Mariusz Gajda,1 and Tomasz Sowinski1

1Institute of Physics of the Polish Academy of Sciences,Al. Lotnikow 32/46, 02-668 Warsaw, Poland

A system of two species of fermions of different mass (m and M) confined ina one-dimensional harmonic trap of frequency ω is studied with an exact diago-nalisation approach. Hamiltonian of system of N↓ light and N↑ heavy particles,interacting via δ-like potential between interspecies particles, reads

H =

N↓∑

i=1

[− h2

2m

∂2

∂x2i+mω2

2x2i

]+

N↑∑

i=1

[− h2

2M

∂2

∂y2i+Mω2

2y2i

]+g1D

N↓,N↑∑

i,j=1

δ(xi−yj). (1)

We show that a mass difference between fermionic species induces a separation inthe density of the lighter flavour independently of the number of particles (Fig.1).The mechanism behind the emergent separation is explained phenomenologicallyand confirmed by direct studies of the ground state of the system. The separationdriven by a mass difference is robust to the interactions with thermal environment.This fact and the great precision achieved in recent experiments let us believe thatthe phase separation in two-flavour mixtures can be confirmed in near future.

FIG. 1. Single particle density of a ground state for strongly interacting particles fora mass ratio corresponding to lithium-potassium (red thick and blue thin line respec-tively) mixture. The spatial separation is always present in the lighter component.

[1] D. Pecak, M. Gajda and T. Sowinski, arXiv:1506.03592


20

Mon

day

Dissipative engineering of spin-entangled states in FermiGases

Jorge Yago,1, ∗ Suzanne McEndoo,1 and Andrew Daley1

1Department of Physics and SUPA, University of Strathclyde16 Richmond St, Glasgow G1 1XQ, UK

In the last few years, a huge effort has been made towards the generation of highlyentangled states, whose enormous applications range from quantum simulationto metrology. We propose a new scheme, based on dissipative dynamics, forthe preparation of spin-symmetric states exploiting statistics of fermions in anoptical lattice which are coupled to a BEC reservoir[1]. We make use of thecorrespondence between spatial and spin symmetries in fermions and the factthat for ultracold atoms the dominant scattering is s-wave two-body collisions,which is spatially symmetric, to dynamically filter out the desired spin symmetrysector. Previously, proposals suggested to use this collisional mechanism at thecost of a significant decrease in the particle number[2]. By combining a Ramancoupling between lattice bands and the dissipative coupling with a BEC reservoir,this new scheme prepares a spin-symmetric state preserving the particle number.

FIG. 1. Proposed implementation combining Raman transfer between bands andcoupling to a BEC reservoir with coupling ratio Γ.

[1] A. J. Daley, P. O. Fedichev, and P. Zoller, Phys. Rev. A 69, 022306 (2004).[2] M. Foss-Feig, A. J. Daley, J. K. Thompson, and A. M. Rey, Phys. Rev.

Lett. 109, 230501 (2012).

∗ [email protected]; http://cnqo.phys.strath.ac.uk/people/postgraduate-students/

21

Monday

Dynamic control of on-demand single photons from acoupled atom-cavity system

Tom Barrett,1, ∗ Oliver Barter,1 Annemarie Holleczkek,1 and Axel Kuhn1

1Clarendon Laboratory, University of Oxford, Parks Road, Oxford, OX1 3PU

An on-demand single photon source enhances the capabilities of both quantumtechnologies and the exploration of fundamental quantum phenomena. Muchof this work utilises SPDC (Spontaneous Parametric Down-Conversion) sources.Here we present an alternative source based on driving a V-STIRAP (Vacuum-induced STImulated Raman Adiabatic Passage) process in 87Rb atoms loadedinto a high-finesse optical cavity. Not only does this scheme offer the prospectof approaching deterministic photon generation but it also provides unparalleledcontrol of the photon’s themselves. This control extends to arbitrarily shapingthe photons’ wavepackets [1], which, along with a long temporal profile of up to600 ns, allows a single photon to be distributed across multiple time-bins. By ap-plying a relative phase to each of these time-bins we can realise a single photon asa general time-bin encoded qu-d-it [2]. The application of this source to quantuminformation has been further explored by its integration with a photonic chip [3].More recently, feedback from classical photo-detection measurements was used toconditionally change the phase of a photon - allowing us to demonstrate dynamiccontrol of the quantum state to deterministically route two photons interferingon a beam splitter.

(a)

)

P3/2

S1/2

Pump l

aser

PBS

MOT and atomic fountain

PBS(b)

(A) (B)F’=1

F=2

F=1

Pum

p la

ser

Ram

an

Cav

ity

D2 l

ine

52P3/2

52S1/2

Pump l

aser

FIG. 1. An illustra-tion of the appara-tus, (a), that gen-erates single pho-tons by driving a V-STIRAP process onthe 87Rb D2 line asshown in (b).

[1] P.B.R. Nisbet-Jones et al., New Journal of Physics, 13(10):103036 (2011)[2] P.B.R. Nisbet-Jones et al., New Journal of Physics, 15(5):053007 (2013).[3] A. Holleczek et al., arXiv:1508.03266 (2015).


22

Mon

day

Nonreciprocal light propagation based on chiral interactionof light and matter

Elisa Will,1, ∗ Adele Hilico,1 Michael Scheucher,1

Jurgen Volz,1 and Arno Rauschenbeutel1

1Atominstitut − TU ViennaStadionallee 2, 1020 Vienna, Austria

Nanophotonic components confine light at the wavelength scale and enable thecontrol of the flow of light in an integrated optical environment. Such strongconfinement leads to an inherent link between the local polarization of the lightand its propagation direction - the light obtains a chiral character - and therebyfundamentally alters the physics of light-matter interaction [1].We employ this effect in order to investigate the realization of novel nonreciprocaloptical devices that operate at the single-photon level. For this purpose, we usea single spin-polarized 85Rb atom that is strongly coupled to an optical nanofibervia a novel type of whispering-gallery-mode microresonator - a so-called bottlemicroresonator [1]. These resonators offer the advantage of being fully tunableand provide very long photon lifetimes in conjunction with near lossless couplingto the nanofiber. This renders them ideal for the investigation of nonreciprocallight propagation based on chiral light-matter interaction.In a first experiment, we study the on-resonance performance of the system andobserve a strong imbalance between the transmissions in forward and reversedirection of 13 dB while, at the same time, the forward transmission still exceeds70 % [2]. The resulting optical isolator exemplifies a new class of nanophotonicdevices based on chiral interaction of light and matter, where the state of a singlequantum emitter defines the directional behavior.

[1] C. Junge et al., Phys. Rev. Lett. 110, 213604 (2013).[2] C. Sayrin et al., arXiv:1502.01549 (2015).


23

Monday

Extraction of a Single Photon from an Optical Pulse

Orel Bechler,1, ∗ Serge Rosenblum,1 Itay Shomroni,1

Yulia Lovsky,1 Gabriel Guendelman,1 and Barak Dayan1

1AMOS and Department of Chemical Physics,Weizmann Institute of Science, Rehovot 7610001, Israel

In recent years, there have been significant advances in the control and manipu-lation of fundamental quantum systems. One of the growing interests in the fieldof quantum optics has been the realization of single photon subtraction, in whichexactly one photon is always removed from an incoming laser beam. Histori-cally, such schemes are implemented in an inefficient and probabilistic manner,in which a successful subtraction is heralded by the detection of a subtractedphoton, which is consequently lost.

Here we experimentally demonstrate a passive scheme for the deterministicextraction of a single photon from an incoming pulse, in which the removed pho-ton is conveniently extracted to a different mode before it is detected [1]. Ourimplementation makes use of the single-photon Raman interaction (SPRINT)mechanism using a single atom coupled to a microsphere resonator [2]. Thisscheme is generic in the sense that it can be applied on any atom-like three-levelΛ-system in which each transition is coupled to a different guided mode.

[1] Serge Rosenblum, Orel Bechler, Itay Shomroni, Yulia Lovsky, Gabriel Guendelman,and Barak Dayan. ”Extraction of a single photon from an optical pulse.” NaturePhotonics (2015).

[2] Itay Shomroni, Serge Rosenblum, Yulia Lovsky, Orel Bechler, Gabriel Guendelman,and Barak Dayan. ”All-optical routing of single photons by a one-atom switch con-trolled by a single photon.” Science 345, no. 6199 (2014): 903-906.

∗ [email protected] ; http://www.weizmann.ac.il/chemphys/dayan/

24

Mon

day

Open-loop four-wave mixing as a light-atom interface

Micha l Parniak,1, ∗ Adam Leszczynski,1 and Wojciech Wasilewski1

1Institute of Experimental Physics, Faculty of Physics,University of Warsaw, 02-093 Warsaw, Poland

We demonstrate an interface between light coupled to transition between ex-cited states of rubidium and long-lived ground state atomic coherence ρgh. Inour proof-of-principle experiment a non-linear process of four-wave mixing in anopen-loop configuration is used to achieve light emission proportional to indepen-dently prepared ground-state atomic coherence. We demonstrate strong correla-tions between Raman Stokes scattering [1] (a two-photon process 2Ph) heraldinggeneration of ground state coherence ρgh and the new four-photon signal (4Ph)obtained in an open-loop four-wave mixing process [2]. Dependance of the effi-ciency of the process on laser detunings is studied.

2

3

gh

g

h4

780 nm

776 nm

1

2

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4Ph

δ(a) (b)

(c) 4Ph

ground state

coherence

Wol

Rb cell

λ/2

PBSAPD

PD

1

2

4

4Ph

2Ph(e)

(d) 2Ph

FIG. 1. Level configuration of 87-Rb atom (a) used in the experiment, correlationbetween the two-photon Raman signal generating atomic coherence and the novelfour-photon process (b), together with exemplary pulse shapes and average intensity(c,d) and the experimental configuration of the main cell (e).

[1] R. Chrapkiewicz, W. Wasilewski, Optics Express 20 29540 (2012).[2] M. Parniak, W. Wasilewski, Phys. Rev. A 91, 023418 (2015).

∗ [email protected]; http://psi.fuw.edu.pl

25

Monday

N-photon generator based on Raman quantum memory

Micha l Dabrowski,1, ∗ Rados law Chrapkiewicz,1 and Wojciech Wasilewski1

1Institute of Experimental Physics, University of WarsawPasteura 5, 02–093 Warsaw, Poland

Quantum memories are as necessary for quantum information processing as theelectronic memories are for the classical computers. The multimode capacity is ina sense equivalent to having a register of bits instead of a single bit. Here we reportthe first to our knowledge experimental demonstration of high-capacity, spatiallymultimode warm atomic memory operating at the single-photon-level. Our im-plementation relying on spontaneous write-in inside the memory overcomes theneed of matching the heralded photons from the external source with the atoms.Instead, the write-in is heralded by the Stokes scattered photons which are gener-ated inside the memory. The super-efficient triple filtration system provides highsignal to noise ratio and the ultra-low-noise intensified sCMOS camera sensitiveto single photons allows us to count scattered photons with photon-number andspatial resolution. The particular realization in a warm atomic vapours may enablerobust implementations in the future.

FIG. 1. (a) Maps of g(2)S,AS cross-correlation between Stokes and anti-Stokes photons

for increasing storage times. Photons are counted in small circular regions of 0.02mrad2 around directions θ

(S)x , θ

(AS)x and their maximum mean number do not exceed

〈n〉 < 0.5. (b) The ratio of widths of the correlation maps in the anti-diagonal σ′, anddiagonal σ directions yield the estimated number of retrieved modes N ' (σ′/σ)2.

∗ [email protected]; http://www.optics.fuw.edu.pl/en/

26

Mon

day

27

Tuesday

Talks: Tuesday, February 23

Francesca Ferlaino, University of InnsbruckFrancesca Ferlaino is Professor of physics atthe University of Innsbruck and Research Di-rector of the Institute for Quantum Opticsand Quantum Information. She studied phy-sics at the University of Napoli and at theInternational School for Advanced Studies. Du-ring her PhD she experimentally investiga-ted atomic Fermi gases in optical latticesat the University of Florence. After a post-doctoral fellowship at the European Labo-ratory for Non-Linear Spectroscopy (LENS)in Florence she moved to Innsbruck to con-tinue her research in the field of ultracoldatoms and quantum gases. In 2011 she be-came an associate professor and in 2012 auniversity professor for atomic physics in Inns-bruck.

Francesca’s active research interests include fundamental few- and many-bodyphenomena realized with ultra-cold quantum gases of atoms and molecules. Shealso works on exotic states of matter such as giant three-body states, quantumdipolar gases of highly magnetic erbium atoms and ultra-cold polar molecules.

28

Tues

day

The Fascination of Lanthanides for Ultracold QuantumPhysics

Francesca Ferlaino1

1Institut fur Experimentalphysik, Universitat Innsbruck andIQOQI-Institut fur Quantenoptik und Quanteninformation,

Osterreichische Akademie der Wissenschaften, 6020 Innsbruck, Austria

Given their strong magnetic moment and exotic electronic configuration, lan-thanide atomic species disclose a plethora of intriguing phenomena in ultracoldquantum physics. The large magnetic moment of these atoms reflects on a stronginterparticle dipole-dipole interaction, which has both a long-range nature and anisotropic character. Here, we report on our latest results on quantum many-bodyand few-body physics based on a strongly-magnetic lanthanide, erbium (Er). Par-ticular emphasis will be given to the scattering properties of bosonic and fermionicEr, in which unconventional and fascinating phenomena appear as a result of boththe magnetic and the orbital anisotropy of the underlying the native interactionsbetween atoms.

29

Tuesday

Studying quench dynamics in an ultracold quantum gas bynear-field interferometry

Christian Baals,1, ∗ Bodhaditya Santra,1 Ralf Labouvie,1 and Herwig Ott1

1Research Center OPTIMAS and Fachbereich Physik,Technische Universitat Kaiserslautern

Erwin-Schrodinger-Str. 46, 67663 Kaiserslautern, Germany

The effect of interferometric self-imaging in the near-field, also known as Talboteffect, has been exploited in many areas of research since its discovery in the 19thcentury.In our experiment a situation similar to the temporal Talbot effect is used tomeasure the coherence length of a matter-wave field. A Bose-Einstein conden-sate of Rb-87 is loaded adiabatically into a 1D or a 3D optical lattice where thecoherence can be tuned via the potential depth. Subsequently, the lattice poten-tial is switched off and on again for a short time. The momentum distribution isobserved in absorption images after time-of-flight where the width of the centralpeak serves as a measure of coherence.For a superfluid this width shows oscillations where the period corresponds tothe Talbot time. In the Mott-insulating regime these oscillations disappear butcan be restored by quenching the system to the superfluid regime before thepulse is applied. With increasing waiting time between the quench and the pulsethe coherence length increases which can directly be seen by the appearance ofoscillations in the measurement signal.

∗ [email protected]; http://www.physik.uni-kl.de/ott/

30

Tues

day

Two dipolar atoms in a harmonic trap

Rafa l O ldziejewski,1, ∗ Wojciech Gorecki,1 and Kazimierz Rzazewski1

1Center for Theoretical Physics, Polish Academy of SciencesAl. Lotnikow 32/46, 02-668 Warsaw, Poland

Recently it has became possible to study experimentally spectra of two interactingatoms (molecules) in a harmonic trap. So far mostly the contact interaction wasinvestigated [1, 2]. Of interest, however, is also long range magnetic (electric)dipole - dipole interaction. We investigate theoretically such systems for two iden-tical atoms of different spins (fermions or bosons). We obtain exact numericalsolutions in the absence of external fields [3]. Anti-crossings of the energy levelsis observed as a function of the dipolar coupling constant. We envisage that thesystem could be adiabatically pumped from the s-wave to d-wave, which consti-tutes an analogue of Einstein - de Hass effect [4]. Our results may be checkedexperimentally e.g. for the dysprosium atoms by varying the trap frequency.

0.000 0.002 0.004 0.006 0.008 0.0100

0.5

1.5

3.5

DIPOLAR COUPLING CONSTANT

EN

ER

GY

S1=S2=21/2

0.000 0.001 0.002 0.003 0.004 0.0050

2

4

6

DIPOLAR COUPLING CONSTANT

<L

2>

S1=S2=21/2

FIG. 1. The first three energy levels vs dipolar coupling constant and correspondingexpected value of orbital angular momentum operator

⟨L2

⟩. The black solid line

represents the ground state, the red dashed dotted line and blue dashed line indicatefirst and second excited states respectively for the two identical atoms of spin s1 =s2 = 21

2. The inset magnifies the anti-crossing area.

[1] Th. Bush, B.G. Englert, K. Rzazewski, and M. Wilkens, Foundations of Physics 28549 (1998)

[2] M. Kohl, K. Gunter, T. Stoferle, H. Moritz, and T. Esslinger, J. Phys. B 39 S47(2006)

[3] R. O ldziejewski, W. Gorecki, K. Rzazewski, in preparation[4] A. Einstein, W.J. de Haas, Verh. Dtsch. Phys 17, 152 (1915)

∗ [email protected]; http://www.cft.edu.pl

31

Tuesday

A trapped atom interferometer for short range forcesmeasurement

Xavier Alauze,1, ∗ Cyrille Solaro,1 Matthias Lopez,1

Alexis Bonnin,1 and Franck Pereira Dos Santos1

1SYRTE, Observatoire de Paris, LNE, CNRS, UPMC,61 Avenue de l’Observatoire, F-75014, Paris, France

In our experiment, we realize a trapped atom interferometer of 87Rb in a verticaloptical lattice. For shallow lattices, stimulated Raman transitions can be usedto induce coherent transport between adjacent Wannier-Stark states (figure 1 -left), allowing us to perform atom interferometry and to measure with very highaccuracy, shifts in the Bloch frequency. A good control and understanding of thelight shifts induced by the trapping lasers leads to a force sensor with a maximalrelative sensitivity of 1.8 10−6 at 1 s. [1, 2]An optical dipolar trap has recently been installed to perform evaporative coolingin order to increase the atomic density. Atom interactions now produce parasiticshifts on the Bloch frequency and affect the coherence of the interferometer. Westudy, in our configuration, the impact of the identical spin rotation effect (ISRE),i.e a spin self-rephasing mechanism due to particle indistinguishability, that cangive rise to very long coherence time in trapped atomic clocks [3].

FIG. 1. Left: Wannier-Stark ladder where νB ≈ 568.5Hz is the Bloch frequency. -Right: Ramsey-Raman fringes for a lattice depth Ul = 3.9Er.

[1] B. Pelle, et al., Physical Review A 87, 023601 (2013)[2] A. Hilico, et al., Physical Review A 91, 053616 (2015)[3] C. Deutsch, et al., Physical Review Letters 105, 020401 (2010)

∗ [email protected]; http://syrte.obspm.fr/tfc/capteurs˙inertiels/frame.html

32

Tues

day

Microwave spectroscopy of nanofiber-trapped Cesium atoms

Yijian Meng,1, ∗ Bernhard Albrecht,1 Christoph Clausen,1

Philipp Schneeweiss,1 and Arno Rauschenbeutel1

1Vienna Center for Quantum Science and Technology, Atominstitut,Vienna University of Technology, 1020 Vienna, Austria

Hybrid quantum systems are promising candidates for realizing a quantum net-work. A particularly interesting approach is the optical nanofiber based atom-photon interface [1]. Using evanescent lights that are blue and red detuned tothe atomic resonance, cold neutral atoms are trapped at a distance of 200 nm awayfrom the nanofiber surface. This allows efficient coupling between the trappedatoms and an additional resonant fiber guided light through its evanescent field.Control of atoms’ internal degrees of freedom has been demonstrated extensivelyin the nanofiber based system, including Zeeman state preparation, coherent darkstate preparation, and light storage [2, 3]. However, for complete control, onehas to be able to manipulate the external degrees of freedom. To characterizethe motional states of the trapped atoms, we take the microwave spectra of thehyperfine ground state manifold. Due to spin state dependent trapping poten-tials, we can drive microwave transitions between different vibrational states [4].In the microwave spectra, the vibrational sidebands appear at the integer multi-ples of the trap frequencies centered around the carrier transition. We use theratio between the area of the first blue and red sideband to estimate the averagevibrational state of the atomic ensemble, yielding a mean occupation number ofabout 3. Furthermore, we plan to cool fiber-trapped atoms by driving microwavetransitions to lower vibrational states [5]. Once atoms are cooled, the coherencetime will increase as the influence of light shift is reduced. This can be benefi-cial for realizing a quantum memory , which is an important building block forquantum communication.

[1] E. Vetsch et al., Phys. Rev. Lett. 104, 203603 (2010).[2] D. Reitz et al., Phys. Rev. Lett. 110, 243603 (2013).[3] C. Sayrin et al., Optica 2, 353 (2015).[4] L. Fam et al., Phys. Rev. A. 88, 033840 (2013).[5] L. Forster et al., Phys. Rev. Lett. 103 233001 (2009).


33

Tuesday

Feedback-based position stabilisation of microparticles

Saravanan Sengottuvel,1, ∗ Michael Johanning,1 and Christoph Wunderlich1

1University of SiegenEmmy-Noether Campus, Walter-Flex Str. 3, 57072, Germany

We report on the status of an experiment utilizing feedback for the three-dimensional position stabilization of a charged micro particle. Laser light scat-tered by the particle illuminates position sensitive detectors and generates anerror signal upon displacement of the particle. This error signal is then used togenerate a compensating field using correction electrodes. For a particle that isinitially trapped in a linear segmented Paul trap, this allows to ramp down andfinally switch off the trap and end up with a well localized quasi-free particle.We discuss the approach, potential applications and limitations for sensitivity,position confinement and particle size.

[1] Wolfgang Paul, Rev. Mod. Phys. 62: 531540 62, 531 (1990).


34

Tues

day

Digital-Analog Quantum Simulation of Spin Systems inTrapped Ions

Inigo Arrazola,1, ∗ J. S. Pedernales,1 L. Lamata,1 and E. Solano1, 2

1Department of Physical Chemistry,University of the Basque Country UPV/EHU,

Apartado 644, E-48080 Bilbao, Spain.2IKERBASQUE, Basque Foundation for Science,Maria Diaz de Haro 3, E-48013 Bilbao, Spain.

We propose a method to simulate spin models in trapped ions, using digital-analog techniques [1]. With a suitable multiqubit gate decomposition in termsof analog blocks (many-body dynamics of the simulator) and digital steps (one-and two-qubit gates), we show that the dynamics of the spin-1/2 Heisenbergchain can be implemented in a linear ion array. We demonstrate that this hybridtechnique reduces the experimental requirements of both, exclusively analog ordigital approaches, making it a good candidate for experimental implementations.Our work may be adapted to different quantum platforms.

FIG. 1. Digital-analog protocol for a Trotter step to simulate the Heisenberg model.

[1] I. Arrazola, hdl.handle.net/10810/15749 (2015).

∗ [email protected]; http://www.qutisgroup.com/inigo-arrazola/

35

Tuesday

Time and Spatial Parity Operations with Trapped Ions

Xiao-Hang Cheng,1, 2, ∗ Unai Alvarez-Rodriguez,2

Lucas Lamata,2 Xi Chen,1 and Enrique Solano2, 3

1Department of Physics, Shanghai University,Shangda Rd. 99, 200444 Shanghai, China

2Department of Physical Chemistry,University of the Basque Country UPV/EHU,

Apartado 644, 48080 Bilbao, Spain3IKERBASQUE, Basque Foundation for Science,Maria Diaz de Haro 3, 48013 Bilbao, Spain

We propose a physical implementation of time and spatial parity transformations,as well as Galilean boosts, in a trapped-ion quantum simulator. By embeddingthe simulated model into an enlarged Hilbert space, these fundamental symmetryoperations can be fully realized and measured with ion traps. We illustrate ourproposal with analytical and numerical techniques of prototypical examples withstate-of-the-art trapped-ion platforms. These results pave the way for the real-ization of time and spatial parity transformations in other models and quantumplatforms.

|e2>|g2> ⊗

|e1>|g1>

|n>

|2>|1>|0>

⊗

FIG. 1. Scheme of the proposed experiment for the implementation of time, spatial,and Galilean transformations. Two ions are needed for the time parity and Galileanboost, while a single ion suffices for the spatial parity.

[1] Xiao-Hang Cheng, et al., Phys. Rev. A 92, 022344 (2015).

∗ [email protected]; http://www.qutisgroup.com/m-sc-xiao-hang-cheng/

36

Tues

day

Relaxation dynamics of a one-dimensional Bose gas

F. Cataldini,1, ∗ T. Langen,1 S. Erne,1, 2, 3 R. Geiger,1 B. Rauer,1 T.

Schweigler,1 I. E. Mazets,1, 4, 5 T. Gasenzer,2, 3 and J. Schmiedmayer1

1Vienna Center for Quantum Science and Technology,Atominstitut, TU Vienna, Austria

2Institut fur Theoretische Physik, Ruprecht-Karls-Universitat Heidelberg, Germany3ExtreMe Matter Institute EMMI, GSI, Darmstadt, Germany

4Wolfgang Pauli Institute, Vienna, Austria5Ioffe Physico-Technical Institute, St. Petersburg, Russia

In the last years, cold atomic gases developed into a versatile testbed for thestudy of many different physical phenomena. In particular for the investigation ofrelaxation and thermalization dynamics in isolated quantum systems they repre-sent a powerful tool and sparked a lot of research activity. In our group we havedeveloped techniques to characterize relaxed states and the dynamics leading tothem.Our system is a quantum degenerate 1D Bose gas of 87Rb that is taken outof equilibrium by coherently splitting it into two parts. The dynamics of thesystem after the quench is characterized by a loss of the initial coherence and theappearance of a thermal-like steady state. Despite important theoretical effort,no generic framework exists yet to understand when and how a quantum systemapproach thermal equilibrium. However, studying phase correlations between thetwo gases we show that this steady state can be described by a generalized Gibbsensemble [1].

[1] T. Langen et al., Science 348, 207 (2015).

∗ [email protected]; www.atomchip.org

37

Tuesday

Inducing Bose condensation with a hot needle

Alexander Schnell,1, ∗ Daniel Vorberg,1

Roland Ketzmerick,2, 1 and Andre Eckardt1

1Max-Planck-Institut fur Physik komplexer Systeme,Nothnitzer Straße 38, 01187 Dresden, Germany

2Technische Universitat Dresden,Institut fur Theoretische Physik, 01187 Dresden, Germany

A quantum system exchanging energy with a thermal bath will assume an equi-librium state that is completely determined by the bath temperature. In contrast,when the system is driven out of equilibrium, e.g. by coupling it to two bathsof different temperatures, the system will assume a non-equilibrium steady statethat does not only depend on the bath temperatures, but on the very details ofthe system bath coupling.This offers great freedom to tailor the properties of a system by bath engineeringand can also give rise to counter intuitive effects. We consider an ideal one-dimensional Bose gas immersed in a cold bath. We show that the coherencelength of the system can be increased by several orders of magnitude by couplingit additionally to a ”hot needle” (a second, spatially localized bath that is muchhotter than the first one). As a consequence, Bose condensation can be inducedby a hot needle in a system of finite extent.

∗ [email protected]; http://qcqd.pks.mpg.de

38

Tues

day

39

Wednesday

Talks: Wednesday, February 24

Michael Fleischhauer, TU KaiserslauternMichael Fleischhauer is Professor for theoretical physicsat the TU Kaiserslautern. He studied physics at theFriedrich-Schiller University of Jena. In 1991 he receivedhis PhD in physics with a work dedicated to the gene-ration, optical processing and detection of non-classicallight and in the year 2000 he finished his habilitationat the LMU Munich with a thesis titled “Electromagne-tically Induced Transparency in Optically Thick Media”.Besides other positions, in 1991 he became a researchassociate at the Center for Advanced Studies in NewMexico, Albuquerque, U.S.A. and in the following yearshe visited various research groups including the ITAMPat Harvard University. Since 2010 he is a member of

the editorial board of PRL and since 2012 he is also a member of the board ofthe German Physical Society.

His research interests include: Electromagnetically induced transparency, slowand stationary light and applications in quantum information and many-bodyphysics. He is also studying strongly interacting one-dimensional systems andtheir numerical simulation, as well as many-body physics in Rydberg gases andRydberg polaritons. Furthermore, he investigates phases and phase transitions innon-equilibrium steady states of open systems and Quantum Hall and symmetryprotected topological systems.

40

Wed

nesd

ay

Many-body correlations in open systems: Optically drivenRydberg gases

Michael Fleischhauer1

1Fachbereich Physik und Forschungszentrum OPTIMAS,Technische Universitat Kaiserslautern,D-67663 Kaiserslautern, Germany

Quantum optical realizations of many-body systems must often be considered asopen systems and thus offer a way to study correlations and phase transitionsin the non-equilibrium steady-state. These questions will be addressed for theexperimentally relevant example of optically driven Rydberg gases. Here thereare two different regimes of the many-body dynamics depending on the resonanceconditions of the optical excitation.Under conditions of resonant excitation the long-range van-der Waals repulsionresults in an effect called Rydberg blockade. The interaction drives the systeminto a state with crystalline order but compete with fluctuations inherent to theopen system. Quantum correlations in the steady state are calculated by time-dependent density-matrix renormalization group (t-DMRG) simulations for opensystems in one spatial dimension and effective rate equation models in higherdimensions. I will discuss similarities and differences of the observed steady-statephase transition from phase transitions in equilibrium systems.For off-resonant excitation, where the driving field is tuned out of resonance, ananti-blockaded situation is established. Here the presence of a single excitationshifts other atoms at a certain distance into resonance causing a fast excitationcascade. Mean field approximations to the many-body dynamics predict a bi-stable steady state. I will critically examine the existence of bistability in thissystem based on t-DMRG simulations and discuss the underlying physical pro-cesses.

41

Wednesday

Enhanced quantum simulation of quantum phase transitionsusing non-destructive measurements

Otto Elıasson,1, ∗ Mark Bason,1 Robert Heck,1 Aske R. Thorsen,1

Romain Muller,1 Mario Napolitano,1 Jan Arlt,1 and Jacob Sherson1

1Institute of Physics and AstronomyNy Munkegade 120, 8000 Aarhus, Denmark

In the age of quantum simulation, experiments must give as tight bounds as possi-ble to guide the construction of theoretical models describing complex many-bodyquantum systems. By using QND (quantum non-demolition) measurements ofultracold atomic clouds combined with data processing one may obtain a signif-icant reduction of classical noise sources. Here we characterize the onset of thephase transition of a cold atomic cloud to a Bose-Einstein condensate (BEC) withsuch measurements.We report on three separate investigations using Faraday imaging, a methodrelying on the dispersive light-matter interaction [1]. First we report that the shot-to-shot fluctuating initial conditions in the cold atomic cloud deterministically shiftthe transition point to a BEC. Then we demonstrate that precise knowledge ofthese initial conditions lead to enhanced precision in the determination of thetransition point. Secondly, we probe the dynamics of the condensation processby repeated in-situ Faraday images of the same cloud. We quantify experimentalsources of noise and demonstrate that the transition point depends on the numberof probe photons, in a deterministic manner. This is an important step towardsdirect observation of the stochastic nature of the condensation process, due tobosonic stimulation. Finally, as a step towards single shot mapping of entire phasediagrams we quasi-conservatively drive the transition to BEC up to 30 times usingrepeated application of a tightly focussed light beam (a dimple).

[1] M. Bason et al. Charactering QND observation of transitions to BEC. In preperation.


42

Wed

nesd

ay

Tunneling dynamics of interacting Bose-Einstein condensatesin a double-well potential

Marine Pigneur,1, ∗ T. Berrada,1 T. Schumm,1 and J. Schmiedmayer1

1Vienna Center for Quantum Science and TechnologyAtominstitut, TU Wien, Stadionallee 2, 1020 Vienna, Austria

Atomic interactions introduce an intrinsic non-linearity in bosonic Josephson junc-tions, making them richer than their condensed matter analogue. We study theeffects of particle interactions on the tunneling dynamics of an elongated Bose-Einstein condensate in a magnetic double-well potential, realized on an atom chip.Using radio-frequency dressing, we deform a single harmonic atom trap, in whichthe atoms are initially condensed, into a double-well potential and realize a split-ting of the BEC wave function. A large spatial separation and a tilt of thedouble-well enable us to prepare a broad variety of initial states by precisely ad-justing the initial population and relative phase of the two wave packets, whilepreserving the phase coherence.By re-coupling the two wave packets, we investigate tunneling regimes such asJosephson (plasma) oscillations and macroscopic quantum self-trapping. In bothregimes, we observe that the tunneling dynamics is accompanied by a strongdamping mechanism and a relaxation towards a phase-locked equilibrium state.The mechanism is seemingly independent of the recoupling trap, excluding puretransverse effects.We include this damping to a mean-field model as an empirical friction. A moresophisticated approach that we currently investigate consists in studying the cou-pling between transverse and longitudinal directions. We aim at reaching a mi-croscopic understanding of the relaxation mechanism.

FIG. 1. Relaxation of the tunneling dynamics of the relative phase and atom numberdifference of an elongated BEC in a double-well potential in the Josephson oscillationregime. The relaxation occurs at the timescale of 10 ms and translates into a spiraltrajectory in the phase portrait representation.

∗ [email protected]; http://atomchip.org/

43

Wednesday

Non-equilibrium quantum dynamics of unstable spinorBose-Einstein Condensates

Maximilian Pruefer,1, ∗ Philipp Kunkel,1 Daniel Linnemann,1

Helmut Strobel,1 Wolfgang Muessel,1 Christian-Marcel

Schmied,1 Thomas Gasenzer,1 and Markus K. Oberthaler1

1Kirchhoff-Institut for PhysicsIm Neuenheimer Feld 227, 69120 Heidelberg, Germany

Spinor Bose-Einstein condensates allow accessing complex many-particle quan-tum dynamics, as they offer a unique level of experimental control. In ourexperiments, we realize such a system in the internal states of 87Rb. For strongconfinement, the dynamics are restricted to the spin degree of freedom. As a firststep this single-mode situation allows a precise understanding of the underlyingspin physics.

Weakening the optical trapping potential along one direction, the interplay be-tween spatial dynamics and spin-mixing in a one-dimensional system can beaccessed. Bogoliubov theory predicts unstable momentum modes, which areoccupied due to the local creation of atom pairs in opposite momentum modes.Experimentally we find strong spatial correlations for short evolution times. Forlater times, irrespective of different initial conditions the dynamics are governedby many modes but nevertheless general features can be found. We identifyemerging, long living structures correlating the collective spin and the total den-sity of the effective spin-1 system.

I will present our experimental progress in isolating these effects and give a de-tailed introduction into our experimental system, the corresponding manipulationtechniques and the challenges that have to be addressed.

∗ [email protected]; http://www.matterwave.de

44

Wed

nesd

ay

Collapse Dynamics of an Attractive Bose-EinsteinCondensate

Christoph Eigen,1, ∗ Alex Gaunt,1 Aziza Suleymanzade,1

Nir Navon,1 Zoran Hadzibabic,1 and Robert Smith1

1Cavendish LaboratoryJ. J. Thomson Avenue, CB3 0HE, Cambridge, UK

We study the collapse dynamics of an attractive Bose-Einstein condensate con-fined in a box potential. The condensate is only stabilized by its kinetic energy,and is otherwise unstable to collapse. We quantify this stability requirement usingvarious initial atom numbers and box sizes, and contrast our results to previousmeasurements in a harmonic trapping potential [1–3]. Furthermore, we measurethe time required for the collapse to occur and its dependence on relevant physicalparameters.

[1] J. M. Gerton et al., Nature 408 692 (2000).[2] J. L. Roberts et al., Phys. Rev. Lett 86, 4211 (2001).[3] E. Donley et al., Nature 412, 295 (2001).


45

Wednesday

Testing the weak equivalence principle using a dual-speciesatom interferometer in microgravity

Laure Chichet,1, ∗ Laura Antoni-Micollier,1 Brynle Barrett,1

Baptiste Battelier,1 Arnaud Landragin,2 and Philippe Bouyer1

1Laboratoire Photonique numerique et nanosciences,Institut d’Optique d’Aquitaine, rue Franois Mitterand, 33400 Talence, France

2LNE-SYRTE, Observatoire de Paris,CNRS and UPMC 61 avenue de l’Observatoire, F-75014 Paris, France

During the last two decades, new techniques to cool and manipulate atoms haveenabled the development of inertial sensors based on atom interferometry. TheICE project (Interferometre a sources atomiques Coherentes pour l’Espace) aimsto verify the weak equivalence principle (WEP), which postulates that the accel-eration of a body in free-fall in a gravitational field is independent of its internalstructure and of its composition. We are using a compact and transportableatom interferometer, composed of two atomic species, 87Rb and 39K. These twospecies differ in mass by more than a factor of two, increasing the sensitivity topossible violations of the WEP, and they exhibit similar transition wavelengths(780 nm and 767 nm, respectively), which allows us to derive the light from thesame telecom-fiber-based technology. To make precise tests of the WEP, thisexperiment is performed in a microgravity environment during parabolic flightsonboard the Novespace Zero-G aircraft [1]. This offers the possibility to increasethe interrogation time of our interferometers to make more precise accelerationmeasurements. However, due to high levels of vibration noise, it is crucial that wecorrelate the acceleration of the Raman mirror with the signal from the atom in-terferometer in order to reconstruct the interference fringes [2]. During our mostrecent flight campaign, we successfully operated the first dual-species atom in-terferometer in microgravity. More recently, we have implemented grey-molassescooling on the D1-transition of 39K (770 nm), which allows us to reach temper-atures below 6 µK and to increase the contrast of our potassium interferometerby a factor of 4. With this improvement, we anticipate future tests of the WEPat state-of-the-art levels.

[1] R. Geiger et al., Nature Comm 2 474 (2011).[2] B. Barrett et al., New J. Phys. 17 085010 (2015).


46

Wed

nesd

ay

Challenges in matter-wave diffraction of polarizable andpolar molecules at nanomechanical masks

Christian Knobloch1, ∗

1University of Vienna, Faculty of Physics, VCQ, QunabiosBoltzmanngasse 5, A-1090 Vienna, Austria

Double slit experiments and grating diffraction with massive particles count amongthe clearest evidence for the delocalized wave-nature of matter. In this contextmolecular matter-waves are of great interest due to their high degree of com-plexity emerging from their rich internal properties. Here we study the relevanceof Casimir-Polder forces [1] for the coherent evolution of polarizable and polarmolecules in interaction with ultra-thin nanomechanical gratings down to thethickness of single layer of graphene [2]. Sizeable but conservative CP forcescontribute to the population of higher order interference fringes and even foratomically thin gratings. We also notice a strong dephasing effect of the gratingon the diffraction of polar molecules. This finding is of importance for futurematter wave experiments on biological molecular species as most of them exhibita permanent electric dipole moment.

[1] C. Brand et al., Ann. Phys. 527 580591 (2015).[2] C. Brand et al., Nature Nanotechnology 10 845-848 (2015).

∗ [email protected]; http://www.quantumnano.at

47

Wednesday

Collective scattering and oscillation modes of optically boundpoint particles trapped in a single mode waveguide field

Daniela Holzmann1, ∗ and Helmut Ritsch1

1Institute for Theoretical PhysicsUniversity of Innsbruck, Technikerstraße 25, A-6020 Innsbruck, Austria

Collective coherent scattering of laser light induces strong light forces between po-larizable point particles. These dipole forces are strongly enhanced in magnitudeand distance within the field of an optical waveguide so that at low temperaturethe particles self-order in strongly bound regular patterns. The stationary config-urations typically exhibit super-radiant scattering with strong particle and lightconfinement. Here we study collective excitations of such self-consistent crys-talline particle-light structures as function of particle number and pump strength.Multiple scattering and absorption modify the collective particle-field eigenfre-quencies and create eigenmodes of surprisingly complex nature. For larger arraysthis often leads to dynamical instabilities and disintegration of the structures evenif additional damping is present.

∗ [email protected]; http://www.uibk.ac.at/th-physik/people/staffdb/1111153.xml

48

Wed

nesd

ay

New techniques for portable cold atom experiments

P. Ireland,1, ∗ D. Bowman,1 G. D. Bruce,1 P. F. Griffin,2 and D. Cassettari1

1SUPA School of Physics and Astronomy, University of St Andrews,North Haugh, St Andrews, Fife, KY16 9SS, UK

2SUPA Department of Physics, University of Strathclyde,107 Rottenrow, Glasgow, G4 0NG, UK

The drive to miniaturise atom-based metrological devices is an important areain modern research. We report our progress towards realising such a portablesetup with three main results: a) a method of determining vacuum pressure usingcold atoms (Figure 1a), removing the need for a standard vacuum gauge [1], b)the creation of a portable magneto-optical trap (Figure 1b) which we have usedto demonstrate cold atom physics at public events across Scotland, and c) thedevelopment of computer generated holographic techniques for the productionof highly flexible and multi-wavelength optical traps [2] with a simple apparatus.Furthermore we demonstrate the applicability of these holographic traps for twoexperiments: ring traps for rotation sensing [3] and the creation of a cold atomdevice that can be used as an investigation of the topological Kondo effect (Figure1c) [4].

FIG. 1. a) Measurement of varying pressures using a Rb87 MOT [1]; b) The portableMOT apparatus; c) A holographic optical trap for probing the topological Kondoeffect [4].

[1] R. W. G. Moore et al., Rev. Sci. Instrum. 86, 093108 (2015).[2] D. Bowman et al., Opt. Express 23, 8365 (2015).[3] G. D. Bruce et al., Phys. Scr. T143, 014008 (2011).[4] F. Buccheri et al., arXiv:1511.06574 (2015).

∗ [email protected]; http://www.st-andrews.ac.uk/coldatoms

49

Wednesday

State-dependent manipulation of ultra-cold atoms in a ringwaveguide: towards a matter-wave Sagnac interferometer.

Hector Mas,1, ∗ Saurabh Pandey,1 Konstantinos Poulios,1

Ivan Alonso,1 Vasiliki Bolpasi,1 and Wolf von Klitzing1

1BEC and Matter Waves Group, IESL FORTHVassilika Vouton 57, P.O. Box 1527 Heraklion, Greece

Since their proposal, time-averaged adiabatic potentials (TAAP) [1] paved the waytowards the implementation of dynamical, smooth, complex potential landscapesfor ultra-cold neutral atoms and Bose-Einstein condensates (BEC). Of particularinterest, especially for interferometric schemes, is the ring-shaped TAAP waveg-uide, first demonstrated in [2]. Here, we report on the experimental implementa-tion of a plethora of TAAP potentials. We also demonstrate the first step towardsSagnac-type interferometry in a ring-shaped TAAP potential by manipulating twodifferent spin states of 87Rb independently. Specifically, we demonstrate that oneand the same experimental sequence propagates the two spin states in oppositedirections around the ring. We plan to use this for an atom Sagnac interferometerby using the |2, 1〉 and |1,−1〉 clock states. These states were shown to be havelong coherence times [3] and state-selective manipulation utilizing rf-fields [4].

a b c

FIG. 1. a) A full TAAP ring potential in the |2, 2〉 state, b) a bucket of atoms in|1,−1〉 travelling along the ring and c) a tightly confined bucket in |2, 2〉

[1] I. Lesanovsky and W. von Klitzing Phys. Rev. Lett. 99, 083001 (2007).[2] B. Sherlock Phys. Rev. A 83, 043408 (2011).[3] V. Guarrera et al., New J. Phys. 17 083022 (2015).[4] T. Fernholz et al., Phys. Rev. A 75 063406 (2007).

∗ [email protected]; http://www.bec.gr

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51

Thursday

Talks: Thursday, February 25

Immanuel Bloch, Max Planck Institute of Quantum OpticsImmanuel Bloch is Professor and Chair for ex-perimental physics at the LMU Munich, aswell as Director at the Max Planck Instituteof Quantum Optics. He studied physics at theUniversity of Bonn followed by a research visitto Stanford University. In 2000 he obtained hisPhD at the LMU Munich in the group of Theo-dor Hänsch developing an atom laser using aBEC for which he was awarded the Otto HahnMedal. He became a junior group leader at theLMU and started his work on ultracold quan-tum gases. Besides numerous other prices hereceived the Körber European Science Prize

and the International Senior BEC Award.

His current research is concentrated on quantum many-body systems using ultra-cold atoms stored in optical lattices. By creating artificial model systems in opticallattices with highly tunable interaction parameters the group around ImmanuelBloch is capable of simulating the quantum behavior of real solids. With theincreasing amount of control over his systems, Immanuel is a major contributor tobring Richard Feynman’s vision of a universal quantum simulator closer to reality.

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Controlling and Exploring Quantum Matter Using UltracoldAtoms in Optical Lattices

Immanuel Bloch1, ∗

1Max-Planck-Institut fur Quantenoptik,Hans-Kopfermann-Str. 1, 85748 Garching,

Germany and Ludwig-Maximilians Universitat,Schellingstr. 4, 80799 Munchen, Germany

More than 30 years ago, Richard Feynman outlined the visionary concept of aquantum simulator for carrying out complex physics calculations. Today, hisdream has become a reality in laboratories around the world. In my talk I will fo-cus on the remarkable opportunities offered by ultracold quantum gases trapped inoptical lattices to address fundamental physics questions ranging from condensedmatter physics over statistical physics to high energy physics with table-top ex-periment.For example, I will show how it has now become possible to image and controlquantum matter with single atom sensitivity and single site resolution, therebyallowing one to directly image individual quantum fluctuations of a many-bodysystem. Such ultrahigh resolution and sensitivity have also enabled us to detect“Higgs” type excitations occurring at 24 orders of magnitude lower energy scalesthan in high energy physics experiments. I will also show, how recent experimentswith cold gases in optical lattices have enabled to realise and probe artificialmagnetic fields that lie at the heart of topological energy bands in a solid. Usinga novel “Aharonov-Bohm” type interferometer that acts within the momentumspace, we are now able to fully determine experimentally the geometric structureof an energy band.


53

Thursday

Quantum Metrology with Schrodinger Cat States of aRydberg Atom

Frederic Assemat,1, ∗ A. Facon,1 E-K. Dietsche,1 D. Grosso,1

S. Haroche,1 J-M. Raimond,1 M. Brune,1 and S. Gleyzes1

1Laboratoire Kastler Brossel, College de France, CNRS,ENS-PSL Research University, UPMC-Sorbonne Universites,11, place Marcelin Berthelot, 75231 Paris Cedex 05, France

Quantum fluctuations limit the ultimate precision we can access through a quan-tum measurement. For instance if one prepares a large angular momentum J in acoherent spin state represented as a vector on the Bloch sphere, the fundamentalquantum fluctuations of this state due to the Heisenberg uncertainty principlelimits the precision with which one can measure the direction of this vector. Theuncertainty, proportionnal to 1/

√J , defines the standard quantum limit (SQL),

and is the ultimate limit when using quasi-classical states. To go beyond, onethen has to manipulate non-classical states, which allow us to reach the true fun-damental limit given by Quantum Mechanics : the Heisenberg limit (HL), which,in the case of a spin J , scales as 1/J .In our experiment we have used Rydberg atoms to perform a quantum enhancedmeasurement of the electric field. The atom behaves like a J = 49/2 spinthat evolves on a generalized Bloch sphere. Instead of measuring the directionof this spin, we measure the quantum phase accumulated by the spin duringits Ramsey evolution, method that can be implemented by preparing the atomsin a Schrodinger cat like superposition and measuring the dephasing betweenthe two coherent components. Through this process, we realized a single atomelectrometer able to reach a sensitivity of 1 mV/cm for a 100 ns interaction time,which is closed to the Heisenberg limit in this context. The extreme sensitivity ofthis high time- and space-resolved field measurement opens the way to excitingapplications.


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A quantum platform using Rydberg atoms in magneticlattices

David Davtyan,1, ∗ S. Machluf,1 J. Naber,1 M.L. Soudijn,1 A.L.La Rooij,1

C.Sanna,1 H.B.van Linden van den Heuvell,1 and R.J.C. Spreeuw1

1University of AmsterdamScience Park 904,1098 XH Amsterdam, the Netherlands

We present our recent results of research of atomic ensembles in two-dimensionalarray of Ioffe-Pritchard type magnetic traps [1]. Clouds of cold 87Rb atoms areloaded in an array of magnetic lattices separated by 10µm lattice spacing, whichis comparable to the dipole blockade radius between Rydberg atoms. We presentmeasurements on Rydberg excitation in the vicinity of the chip surface, showingmassive stray electric fields due to surface adsorbates. We also show results ofour attempts to remove surface adsorbates by illumination with UV light.

Bchip

FePt

10 mm lattice spacing FePt film

(200nm thick)

FIG. 1. Magnetic trapping with a magnetic Z-wire like array creating a lattice ofmicrotraps.

[1] V.Y.F. Leung, A. Tauschinsky, N.J. van Druten, R.J.C. Spreeuw, Quantum Inf Pro-cess 10 955-974 (2011).

∗ [email protected]; http://iop.uva.nl/research/researchgroups/content/qgqi/quantum-gases-quantum-information.html

55

Thursday

Rydberg Spectroscopy in a Bose-Einstein Condensate

Felix Engel,1, ∗ Michael Schlagmuller,1 Tara Cubel Liebisch,1 Fabian Bottcher,1

Kathrin Sophie Kleinbach,1 Karl M. Westphal,1 Robert Low,1 Sebastian

Hofferberth,1 Tilman Pfau,1 Jesus Perez-Rıos,2 and Chris H. Greene2

15. Physikalisches Institut and IQST, Universitat StuttgartPfaffenwaldring 57, 70569 Stuttgart, Germany

2Department of Physics and Astronomy,Purdue University, 47907 West Lafayette, IN, USA

Spectroscopy of a single Rydberg atom excited within a Bose-Einstein condensateis presented. Not only a frequency shift proportional to the density is observed,as discovered by Amaldi and Segre in 1934, but an asymmetric broadening, whichchanges with the principal quantum number n. The asymmetric line broadeningdepends on the interaction potential energy curves of the Rydberg electron scat-terer with the neutral atom perturber. In particular, we show the relevance of thetriplet p-wave shape resonance of the e--Rb(5S) scattering, which significantlymodifies the interaction potential. When a nS +N × 5S1/2 state is photoas-sociated, neutral atom perturbers near the crossing with the shape resonancepotential become relevant, leading to a large n-dependent line broadening. Wepresent a simple microscopic model for the spectroscopic line shape by treatingthe atoms overlapped with the Rydberg orbit as zero-velocity, independent, point-like particles, with binding energies associated with their ion-neutral separation,and good agreement is found [1].

[1] M. Schlagmuller et al., arXiv:1510.07003 (2015).


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Rydberg excitation of trapped strontium ions

Fabian Pokorny,1, 2, ∗ Gerard Higgins,1, 2 Florian Kress,2 Johannes Haag,2

Christine Maier,3 Quentin Bodart,1 Yves Colombe,2 and Markus Hennrich1, 2

1Department of Physics, Stockholm University, 10691 Stockholm, Sweden2Institut for Experimental Physics,

University Innsbruck, 6020 Innsbruck, Austria3Institute for Quantum Optics and Quantum Information,Austrian Academy of Sciences, 6020 Innsbruck, Austria

Trapped Rydberg ions are a novel approach for quantum information processing[1, 2]. This idea joins the advanced quantum control of trapped ions with thestrong dipolar interaction between Rydberg atoms. For trapped ions this methodpromises to speed up entangling interactions [3] and to enable such operations inlarger ion crystals [4].Here, we report on the first trapped strontium Rydberg ions. A single ion wasconfined in a linear Paul trap and excited to Rydberg states from 25S1/2 to 37S1/2

using a two-photon excitation with 243nm and 304-309nm laser light. The tran-sitions we observed are narrow (a few MHz linewidth) and the excitation canbe performed repeatedly which indicates that the Rydberg ions are stable in theion trap. Similar results were recently reported on a single photon excitation oftrapped calcium ions [5]. Furthermore, the transition linewidth of the Rydbergstates was additionally reduced using counterpropagating beams for laser excita-tion, thus enabling the resolution of Zeeman splitting induced by the magneticfield.The tunability of the 304-309nm laser should enable us to excite our strontiumions to even higher Rydberg levels. Such highly excited levels are required toachieve a strong interaction between neighbouring Rydberg ions in the trap aswill be required for quantum gates using the Rydberg interaction.

[1] M. Muller et al., New J. Phys. 10, 093009 (2008)[2] F. Schmidt-Kaler et al., New J. Phys. 13, 075017 (2011)[3] W. Li, I. Lesanovsky, Appl. Phys. B 114, 37-44 (2014)[4] W. Li et al., Phys. Rev. A 87, 052304 (2013)[5] T. Feldker et al., Phys. Rev. Lett. 115, 173001 (2015)


57

Thursday

Bottom-up approach to many-body physics with ultracoldatoms in adjustable lattices

Martin Sturm,1, ∗ Malte Schlosser,1 Gerhard Birkl,1 and Reinhold Walser1

1Institute of Applied Physics, Technical University DarmstadtHochschulstraße 4a, 64289 Darmstadt, Germany

Ultracold atoms in optical lattices have proven to be a powerful toolbox for quan-tum simulation of many-body physics. With the demonstration of single-siteresolved imaging, local properties have shifted into the focus of this field. Thisdevelopment is complemented by the construction of double-well systems fromsingle atoms in optical tweezers. We present an experimental avenue to scalableand adjustable arrays of optical dipole traps using microlens arrays and spatiallight modulators (Fig. 1 a). This setup closes the gap between the aforemen-tioned approaches and allows for a bottom-up construction of many-body systemsadding one atom at a time. In order to evaluate the experimental feasibility of thisapproach we compute the accessible parameter regime for 87Rb from measure-ments and simulations of the light field (Fig. 1 b). As a possible application weanalyze the tunneling dynamics between two coupled ring lattices. This configura-tion exhibits additional many-body resonances as compared to bosonic Josephsonjunctions in double-well potentials.

1.7 µm

MLA

SLM

trapped atoms

optics

a b

FIG. 1. (a) Schematic experimental setup [1]. (b) Measured intensity distribution.

[1] M. Schlosser et al., Quantum Inf. Process. 10 907-924 (2011).

∗ [email protected]; http://www.iap.tu-darmstadt.de/tqd

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Generation of highly tunable light potentials on atwo-dimensional degenerate Bose gas

Jean-Loup Ville,1, ∗ Raphal Saint-Jalm,1 Laura Corman,1

Jerome Beugnon,1 Sylvain Nascimbene,1 and Jean Dalibard1

1Laboratoire Kastler Brossel / College de France11 Place Marcelin Berthelot, 75005 Paris, France

The first realization of a Bose-Einstein condensate in a uniform potential [1] hasopened new perspectives in the field of ultracold atoms.I will present our new experimental setup designed to study the dynamics ofrubidium atoms in low dimensionnality. This setup has been improved in twoways: the vertical confinement is realized by an optical accordion which allows fora new type of compression and the horizontal confinement is made by a DigitalMicromirrors Device (DMD) combined with a high numerical aperture microscopeobjective. We are thus able to create flat-bottom potentials with arbitrary shapeson a two-dimensional gas.This setup allows us to study more precisely the Kibble-Zurek mechanism (fol-lowing [2]) and to investigate bosonic transport as I will describe depending onour last advances.

FIG. 1. a) Direct imaging of a flat square optical potential imprinted on the atoms.b) Atoms trapped in a target potential.

[1] A. L. Gaunt et al., Phys. Rev. Lett. 110, 200406 (2013).[2] L. Chomaz et al., Nature Comm. 6, 6162 (2015).


59

Thursday

Engineering Many-Body Systems with Quantum LightPotentials and Measurements

Thomas J. Elliott1, ∗ and Igor B. Mekhov1

1Department of Physics, Clarendon Laboratory,University of Oxford, Parks Road,Oxford OX1 3PU, United Kingdom

Interactions between many-body atomic systems and light in cavities induce newatomic dynamics, which we show can be tailored by projective light measure-ment backaction, leading to collective effects such as density-density interactions,perfectly-correlated atomic tunneling, superexchange, and effective pair creationand annihilation. These can be long- and short-range, with tunable strengths,based on the optical setup. We demonstrate that the measurement backactionalso results in the generation of multiple many-body spatial modes of the atoms,with nontrivial spatial overlap and multipartite entanglement properties. We showthis provides a framework to engineer states such as multimode generalizationsof parametric down-conversion and Dicke states, and to enhance quantum sim-ulations of novel physical phenomena, including reservoir models and dynamicalgauge fields, beyond current methods. Furthermore, we propose how the modescan be used to detect and measure entanglement in quantum gases.

FIG. 1. Light is scattered into optical cavities by ultracold atoms trapped in anoptical lattice, leading to new, tunable, dynamical effects for the atoms.

[1] T. J. Elliott et al., Phys. Rev. Lett. 114, 113604 (2015).[2] T.J. Elliott and I. B. Mekhov, arXiv:1511.00980 (2015).

∗ [email protected]; https://www2.physics.ox.ac.uk/contacts/people/elliottt

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Talks: Friday, February 26

Ed Hinds, Imperial College LondonEd Hinds is a Royal Society Research Professorand a Chair in Physics at Imperial College Lon-don. He received his B.A. and D.Phil., both in Phy-sics, from Oxford University. Before joining Impe-rial, Ed worked at Columbia, Yale and the Uni-versity of Sussex. He is the Founder and Directorof the Centre for Cold Matter at Imperial Colle-ge.

Ed’s aim is to study fundamental problems in physicsand to develop new methods for producing and ma-nipulating cold atoms and molecules, leading to newtechnology. His work can be described under three

headings: (i) Quantum manipulation of atoms and photons on atom chips; (ii)Production and applications of cold molecules; (iii) Tests of fundamental physicallaws, especially measurement of the electron’s electric dipole moment (i.e. itsshape). His world-leading group has made huge progress on all three of thesefronts.

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Testing fundamental physics with cold atoms and molecules

E.A. Hinds1

1Centre for Cold Matter, Imperial College London SW7 2AZ

Laser cooling, already very successful in cooling atoms, can now be applied tomolecules. I will discuss the recent advances in that area and the extraordinarysensitivity that this new approach can bring to tests of fundamental physics.Measurements with atto-volt sensitivity help us to search for new physics at energyscales from hundreds of TeV up to the Planck energy. I will describe some of themain ideas and will concentrate on two examples.1) Molecules searching for a permanent electric dipole moment of the electron,strongly constrain possible supersymmetric theories of particle physics.2) Interferometry with cold atoms provides stringent limits on scalar fields thoughtto explain dark energy.

63

F riday

Spin-Mixing Interferometry with Bose-Einstein Condensates

Marco Gabbrielli,1, ∗ Luca Pezze,1 and Augusto Smerzi1

1QSTAR, INO-CNR and LENS, Largo Enrico Fermi 2, I-50125 Firenze, Italy

Interferometry has revealed to be one among the most precise techniques inmetrology. In a interferometer, two (light or matter) waves undergo a phaseshift that generates observable interference effects: the aim of interferometry ismeasuring these effects in order to estimate the phase shift with the smallest pos-sible uncertainty. Entanglement can be exploited to enhance the interferometricsensitivity [1].In a linear interferometer, such as the SU(2) Mach-Zehnder one, beating theshot-noise phase uncertainty requires feeding the interferometer with usefully en-tangled states, that are states in which quantum correlations between particlesare recognized by Fisher information [2]. However, noise and decoherence restrictthe creation and use of such input states.Conversely, in a nonlinear interferometer, such as the SU(1,1) scheme suggestedby Yurke et al. in optical context [3], it is possible to overcome the classicallimitation in sensitivity even with a separable probe state in input, because theuseful entanglement is created inside the interferometer by means of nonlinearinteractions.Interferometry with ultracold trapped atoms has come to the fore in the lastdecade because of its potential in ultraprecise measurements. In this direction,we explore the possibility to design a nonlinear three-mode interferometer using aspinor Bose-Einstein condensate, which exploits entanglement generated by spin-mixing atom-atom interactions to perform sub-shot-noise phase estimation withrespect to the finite resources in input (i.e. the average number of particles inthe condensate). Experimental imperfections due to particle losses and finitedetection efficiency are also taken into account. [4]

[1] V. Giovannetti, S. Lloyd and L. Maccone, Phys. Rev. Lett. 96, 010401 (2006).[2] L. Pezze and A. Smerzi, Phys. Rev. Lett. 102, 100401 (2009).[3] B. Yurke, S. L. McCall and J. R. Klauder, Phys. Rev. A 33, 4033 (1986).[4] M. Gabbrielli, L. Pezze and A. Smerzi, Phys. Rev. Lett. 115, 163002 (2015).


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Two steps condensation in a gas of spin-1 sodium atoms

Andrea Invernizzi,1, ∗ Camille Frapolli,1 Tilman Zibold,1

Karina Jimenez-Garcia,1 Jean Dalibard,1 and Fabrice Gerbier1

1Laboratoire Kastler Brossel, College de France,CNRS, ENS-PSL Research University,

UPMC-Sorbonne Universites 5 place Marcellin Berthelot, 75005, Paris, France

In the talk I will present the results we obtained experimentally studying how Bose-Einstein condensation occurs in a gas of spin-1 sodium atoms . We observed thatthe three Zeeman components of the spinor gas cross the Bose-Einstein phasetransition at different temperatures, with the most populated Zeeman componentcondensing first, as predicted in [1]. We have measured the critical temperaturesof each Zeeman component for different strengths of the magnetic field (whichaffects the thermodynamics via the quadratic Zeeman energy) and different pop-ulation mixtures(see [2]). We have found qualitative agreement with the behaviorof an ideal gas, with quantitative analysis in progress.

FIG. 1. Observation of the two step condensation lowering the temperature. Leftcolumn: absorption images of the three components after a Stern-Gerlach at in-creasing times of the evaporation ramp (lower temperatures); Central column: Fitsof the thermal clouds and Right column: Fits of the condensed fractions.

[1] T. Isoshima et al., J. Phys. Soc. Jpn. 69, 3864 (2000)[2] B. Pasquiou et al., Phys. Rev. Lett. 108 045307 (2012).


65

F riday

Far-field resonance fluorescence for a dipole-interactingatomic gas

Ryan Jones,1, ∗ Reece Saint,1 Igor Lesanovsky,1 and Beatriz Olmos1

1School of Physics and Astronomy, The University of NottinghamNottingham, NG7 2RD, United Kingdom

An open quantum system consisting of two-level atoms coupled to the free electro-magnetic field can exhibit long ranged interactions, when the separation betweenatoms is small compared to their transition wavelength [1]. This dipole-dipole in-teraction is generated by the coherent exchange of virtual photons between atoms.Furthermore, there is a non-local dissipation caused by incoherent transitions inthe system.Here, we investigate the effect of the interactions on the light emitted by thesystem. In particular the case of resonance fluorescence is considered, where thesystem is driven with a laser resonant with the single atom transition frequency.We investigate both the power spectrum of the scattered light, and the temporalcoherence of the photons through the second-order coherence function.In comparison to the non-interacting case [2], the observed power spectrum showsclear signs of collective behaviour. In the case of strong driving, the effects aredemonstrated to be roughly independent of the atomic arrangement. There isalso a modification to the second order coherence, especially for weak drivingwhere emission can be bunched or anti-bunched depending on the system.As these properties are measurable, they can be used to find signatures of col-lective behaviour within current experimental systems which study dipole-dipoleinteraction effects [3].

[1] B. Olmos et al., Phys. Rev. Lett. 110, 143602 (2013).[2] B. R. Mollow, Phys. Rev. 108(5), 1969-1975 (1969).[3] J. Pellegrino et al., Phys. Rev. Lett. 113, 133602 (2014).


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Cold-collision shifts in a unitary Bose gas

Jay Man,1, ∗ Richard J. Fletcher,1 Raphael

Lopes,1 Nir Navon,1 and Zoran Hadzibabic1

1Cavendish Laboratory, University of CambridgeJ. J. Thomson Avenue, Cambridge, CB3 0HE, United Kingdom

At the low energies present in ultracold atomic gases, the scattering length con-trols the strength of inter-atomic interactions. In the mean-field regime, theenergy associated with these interactions causes a ‘cold-collision’ shift in thetransition frequency between internal atomic states [1, 2].Feshbach resonances provide a means of tuning the scattering length. Close toa Feshbach resonance, the scattering length diverges and is replaced by anotherphysical lengthscale, leading to a saturation of interaction-driven properties. Weuse Ramsey spectroscopy to map the cold-collision shift of an interacting Bosegas over a large range of positive and negative scattering lengths, including theunitary regime.

[1] M. Zweirlein et al., Phys. Rev. Lett. 91, 25 (2003).[2] D. M. Harber et al., Phys. Rev. A 66 053616 (2002).

∗ [email protected]; http://www-amop.phy.cam.ac.uk/amop-zh/People.html

67

F riday

Observation of chiral edge states with neutral fermions insynthetic Hall ribbons

Lorenzo Livi1, ∗

1European Laboratory for Non-Linear Spectroscopy (LENS)I-50019 Sesto Fiorentino, Italy

I will report on the study of the edge properties of an ultracold 173Yb Fermigas subjected to an artificial gauge field in a two-dimensional lattice. Adoptingan innovative approach [1] we have used the internal spin degree of freedom ofthe atoms to encode one of the lattice dimensions, realizing in this way a laddergeometry with a variable number of legs. In this ladder system the artificialmagnetic field and the dynamics in the synthetic dimension are realized exploitingtwo Raman beams that couple the different atomic spin states. The possibilityto selectively address each leg allowed us to prove the presence of chiral currentsas well as to observe edge-cyclotron orbits propagating along the edges of theladder [2], thus providing a direct evidence of a fundamental feature of quantumHall physics in condensed-matter systems.

FIG. 1. Sketch of the hybrid lattice used for the experiment.

[1] A. Celi et al., Phys. Rev. Lett. 112, 043001 (2014).[2] M. Mancini et al., Science 349, 6255 (2015).

∗ [email protected]; http://quantumgases.lens.unifi.it

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Squeezed-light spin noise spectroscopy

V.G. Lucivero,1, ∗ R. Jimenez-Martınez,1 Jia Kong,1 and M. W. Mitchell1

1ICFO-Institut de Ciencies Fotoniques,The Barcelona Institute of Science and Technology,

08860 Castelldefels (Barcelona), Spain

“Spin noise spectroscopy” (SNS) has recently emerged as a powerful techniquefor determining physical properties of an unperturbed spin system from its noisepower spectrum both in atomic [1] and solid state [2] physics.Here we report quantum enhancement of SNS via polarization squeezing of theprobe beam up to 3dB [3] over the full density range up to n = 1013 atoms cm−3,covering practical conditions used in optimized SNS experiments.

(a)

(b)

FIG. 1. (a) Experimental schematic. Our experiment combines conventionalFaraday rotation based SNS with a source of polarization squeezing. (b) SNSSpectra. Averaged spin noise spectra at T = 90◦ acquired with coherent probe(cyan) and polarization squeezed probe (red) respectively.

[1] S.A. Crooker et al., Nature 431, 49-52 (2004).[2] J. Hbner et al., Phys. Stat. Sol. B 251, 1824 (2014).[3] V.G. Lucivero et al., arXiv:1509.05653 (2015).

∗ [email protected];

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F riday

Satisfying the EinsteinPodolskyRosen criterion with massiveparticles

K. Lange,1, ∗ J. Peise,1 I. Kruse,1 B. Lucke,1 W. Ertmer,1 C. Klempt,1

L. Pezze,2 A. Smerzi,2 J. Arlt,3 K. Hammerer,4 and L. Santos4

1Institut fur Quantenoptik, Leibniz Universitat HannoverWelfengarten 1, 30167 Hannover, Germany

2INO-CNR and LENS, Largo Enrico Fermi 2, I-50125 Firenze, Italy3Institut for Fysik og Astronomi, Aarhus Universitet,Ny Munkegade 120, DK-8000 Arhus C, Denmark

4Institut fur Theoretische Physik, Leibniz Universitat Hannover,Appelstrasse 2, 30167 Hannover, Germany

Entanglement is one of the key features of quantum mechanics. It was firstdiscussed in the famous thought experiment of Einstein, Podolsky, and Rosen(EPR) [1]. They considered a quantum-mechanical state consisting of two max-imally correlated particles. A measurement of one subsystem seemingly allowsfor a prediction of the second subsystem with a precision beyond the Heisenberguncertainty relation.We utilize spin-changing collisions in a 87Rb Bose-Einstein condensate to gener-ate a two-mode entangled state. By employing an atomic homodyne detection,we verify the EPR correlation according to Reid’s criterion [2]. We find an EPRentanglement parameter of 0.18 which is 2.4 standard deviations below the thresh-old of 1/4. This demonstration of EPR correlations is the first realization withmassive particles [3].Furthermore, the state is fully characterized by a tomographic reconstruction ofthe underlying many-particle quantum state. This reconstruction is obtained viaa Maximum Likelihood algorithm.EPR entangled states are not only interesting from a fundamental point of viewbut can be used for a variety of applications in the field of quantum metrology.

[1] A. Einstein, B. Podolsky, and N. Rosen, Phys. Rev. 47, 777780 (1935).[2] M.D. Reid, Phys. Rev. A 40, 913-923 (1989).[3] J. Peise et al., Nat Commun 6, 8984 (2015).


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Posters: Session A

Poster presentations are divided into two poster sessions, which both take placein the Faculty Club of the TUM Institute for Advanced Study. The pinboardsavailable for the poster session are 88 cm wide and 120 cm high. Therefore, aposter in portrait format is preferred. Please do not exceed A0 poster size. Wewill provide pins/magnets to fix the posters on the walls.

The participants of the session A are:

Name Poster number Name Poster number

Blaha, Martin A72 Lehtonen, Lauri A85

Carey, Max A73 Mohammed, Marwan A86

Compagno, Enrico A74 Mukhtar, Musawwadah A87

Faraoni, Giulia A75 Niemietz, Dominik A88

Gebbe, Martina A76 Panigrahi, Jayash A89

Hannibal, Simon A77 Perrier, Maxime A90

Jin, Shuwei A78 Petter, Daniel A91

Kaiser, Stefan A79 Rubio Abadal, Antonio A92

Kettmann, Peter A80 Sandholzer, Kilian A93

Kurlov, Denis A81 Sobirey, Lennart A94

Kuyumjyan, Grigor A82 Venegas-Gomez, Araceli A95

Lefèvre, Grégoire A83 Zamora-Zamora, Roberto A96

Legaie, Rémy A84 Zimmer, Christian A97

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PostersA

Combined Fluorescence and Absorption Imaging system forNanofiber trapped atoms

Martin Blaha,1, ∗ Jakob Hinney,1 Adarsh Prasad,1 Samuel Rind,1 Philipp

Schneeweiss,1 Jurgen Volz,1 Christoph Clausen,1 and Arno Rauschenbeutel1

1Vienna Center for Quantum Science and Technology, TU Wien - AtominstitutStadionallee 2, 1020 Wien, Austria

In our experiment we plan to establish an atom-light interface as fiber-opticalcomponent for quantum information processing and communication. The keyingredient is an optical nanofiber - a fiber with sub wavelength diameter, thatis used to trap and interface cold atoms [1, 2]. The goal of this experiment isto trap up to 20.000 cesium atoms along the fiber, yielding a very high opticaldensity, as required for many quantum protocols such as quantum memories. Onerequirement for stable trapping is a precise control over the local polarization ofthe nanofiber guided light fields.For this purpose, we developed an imaging technique that allows to analyze scat-tered light from the nanofiber via fluorescence imaging as well as to performabsorption imaging of the MOT-cloud for determining the shape and tempera-ture. In this way, it allows one to adjust and optimize the polarization of thetrapping light as well as the cooling and the loading of atoms into the dipoletrap.

FIG. 1. (a) Illustration of the nanofiber and the optical lattice. (b) Imaging systemfor the measurement of the Rayleigh scattering from the fiber.

[1] Vetsch, E. et al. Phys. Rev. Lett. 104, 203603 (2010).[2] Reitz, D. et al. Phys. Rev. Lett. 110, 243603 (2013).

∗ [email protected]; http://www.nanofiber.at/

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Coherent enhancement of an atom-interferometric rotationsensor

Max Carey,1, ∗ Mohammed Belal,1 and Tim Freegarde1

1Quantum Control Group, University of SouthamptonUniversity Rd, Southampton, SO17 1BJ, UK

Matterwave interferometers can exploit the short de Broglie wavelengths of ultra-cold atoms to make acutely sensitive inertial sensors in the form of gyroscopes [1]and accelerometers [3]. While precise, these devices exhibit drawbacks, both interms of their potential for miniaturisation and in the destructive nature of theirread-out processes.A typical atom interferometry sequence sees an atomic ensemble prepared intoan equal superposition of two quantum states with slightly different momenta,such that they are separated spatially and accrue a phase difference. The su-perposition process is then reversed, mapping this relative phase onto the statepopulations. Although the atoms evolve coherently throughout this process, read-out by measuring the optical absorption or fluorescence of the atoms destroys thequantum coherence so that successive measurements require the ensemble to beprepared afresh. Furthermore, the difference in phase oscillates sinusoidally, sothe atoms can only evolve for a limited period without ambiguity in the eventualmeasurement.We propose a rotation sensor based on new ideas [2] involving the spatial resolu-tion of state populations in a ballistically expanding cloud of cold Rubidium atomswhich has promising miniaturisation potential [4]. We intend to enhance the de-vice by employing read-out schemes pioneered by our collaborators at LaboratoirePhotonique, Numerique et Nanosciences (LP2N) [5]. By making ‘coherence-preserving’ measurements during the interferometric sequence we can extend thedynamic range, allowing for a compact device which exploits the precision of mat-terwave interferometry without many of the shortcomings which could restrict itsusefulness outside of the lab.

[1] T. Gustavson et al., Phys. Rev. Lett. 78, 2046 (1997).[2] S. Dickerson et al., Phys. Rev. Lett. 111, 083001 (2013).[3] A. Bonnin et al., Phys. Rev. A 88, 043615 (2013).[4] S. Riedl et al., Atom Interferometry, Varenna (2013); APS H1.00321 (2014).[5] R. Kohlhaas et al., Phys Rev X 5, 021011 (2015).

∗ [email protected]; http://phyweb.phys.soton.ac.uk/quantum/ 73

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A Minimal Controlled 1D Lattice for Atomic Linear OpticsApplications

Enrico Compagno,1, ∗ Leonardo Banchi,1 and Sougato Bose1

1Department of Physics and Astronomy, University College London,Gower Street, WC1E 6BT London, United Kingdom

Tight-binding lattices offer a unique platform in which particles may be eitherstatic or mobile depending on the potential barrier between the sites. Becausein the typical scenario a particle spreads over multiple sites, how to harness thismobility in a many-site lattice for technological applications is still an open ques-tion.We devise a scheme to trigger effective tunable linear opticslike operations be-tween arbitrary sites in a minimal controlled setup, via a local change in thelattice potential depth [1]. Our strategy overcomes the limitations of setup basedon coherent hopping dynamics, that are used in current experiments (e. g. twowell systems [2, 3]), when atoms are initially separated by many sites.Using the natural hopping dynamics our scheme enables the generation of peculiareffects, as the Hong-Ou-Mandel effect and Hanbury Brown-Twiss correlations.Moreover we implement a Mach-Zehnder transformation by adding a steplikepotential. We specifically address the robustness to imperfections, interactionand environmental effects showing that a high efficiency is possible introducingminimal coupling schemes (i. e. tuning few tunnelling couplings).Finally we design a coupling lattice profile which enables a perfect wavepacketsplitting between mirror symmetric sites, which leads to perfect Hong-Ou-Mandeleffects, perfect wave-packet reconstruction and fractional revivals for arbitrarylong chains [4].

[1] E. Compagno, L. Banchi, S. Bose, Phys. Rev. A 92, 022701 (2015).[2] R. Islam, R. Ma, P. M. Preiss, M. E. Tai, A. Lukin, M. Rispoli, M. Greiner,

arXiv:1509.01160 (2015)[3] A. M. Kaufman, B. J. Lester, C. M. Reynolds, M. L. Wall, M. Foss-Feig, K. R. A.

Hazzard, A. M. Rey, C. A. Regal, et al., Science 345, 306 (2014)[4] L. Banchi, E. Compagno, S. Bose, Phys. Rev. A 91 052323 (2015).


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Disordered Bose-Einstein condensates

Giulia Faraoni,1, ∗ Simona Scaffidi Abbate,1 Lorenzo Gori,1 Chiara

D’Errico,1 Marco Fattori,1 Massimo Inguscio,1 and Giovanni Modugno1

1Lens and Dipartimento di Fisica e AstronomiaVia Nello Carrara 1, 50019 Sesto Fiorentino (Firenze), Italy

The interplay of interactions and disorder in quantum degenerate bosonic systemsis a very general issue of condensed matter physics concerning, for instance, thin-film superconductors and superfluid helium in porous media. While disorder tendsto localize non-interacting quantum particles, weak repulsive interactions lead todelocalization and superfluidity. To directly investigate this competition in realphysical systems is hard due to the impossibility of independently controllingdisorder and interactions. However, it has been demonstrated that this problemcan be addressed using ultracold atoms, which offer unprecedented control andtunability of the disorder parameters and the interaction strength.In Florence we are building a new experiment for studying the whole phase di-agram of a 3D Bose-Einstein condensate of Potassium 39 atoms in presence ofcontrollable interactions and disorder, and finite temperature. The condensatewill be confined in a box-shaped optical trap and subjected to correlated disorderproduced by 3D optical speckles. I will present the ideas for the experiments wewant to perform with our new setup.

Mobility

Bose glass-to-superfluid

phase transition

(1D system)

II

Disorder strength

Mobility

edge

for 3D

Anderson

localization

II

N

SF??

??

Bose-Einstein

condensation

N

SF

??

Temperature

Interaction

energy

FIG. 1. The phase diagram to be explored. I: insulating phase; N: normal conductor;SF: superfluid.

∗ [email protected]; http://www.lens.unifi.it

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Atom-chip gravimetry with Bose-Einstein condensates

Martina Gebbe,1, ∗ Sven Abend,2 Matthias Gersemann,2

Hauke Muntinga,1 Holger Ahlers,2 Ernst M. Rasel,2

Claus Lammerzahl,1 and the QUANTUS Team1, 2, 3, 4, 5, 6, 7

1ZARM, Universitat Bremen, Am Fallturm, 28359 Bremen, Germany2Institut fur Quantenoptik, LU Hannover

3Institut fur Physik, HU Berlin4Institut fur Laser-Physik, Universitat Hamburg5Institut fur Quantenphysik, Universitat Ulm

6Institut fur angewandte Physik, TU Darmstadt7Institut fur Physik, JGU Mainz

Due to their small spatial and momentum width ultracold Bose-Einstein conden-sates (BEC) or even delta-kick cooled (DKC) atomic ensembles are very wellsuited for high precision atom interferometry. We show a combination of suchan ensemble generated in a miniaturized atom-chip setup with the application ofBragg beam splitting to perform different types of inertial sensitive measurements[1, 2]. The chip is not only used for generation, state preparation and delta-kickcooling of the BEC but also serves as retroreflector for the beam splitter and, bythis means, forms the inertial reference.We have realized a compact quantum gravimeter and determined local gravita-tional acceleration g with an accuracy of 1.3·10−5g limited by vibrational noise.We demonstrate that the device’s sensitivity can be enhanced with the help of anoptical lattice to relaunch the atoms and large momentum transfer beam split-ters. Additionally, we introduce a symmetric Double-Bragg diffraction techniquethat offers interesting features for the next generation of atom interferometers.We exploit this to access the axis perpendicular to gravity and demonstrate ge-ometries that are also sensitive to rotations, the platforms tilt as well as gravitygradients all in one single device.This work is supported by the German Space Agency (DLR) with funds providedby the Federal Ministry for Economic Affairs and Energy (BMWi) due to anenactment of the German Bundestag under grant numbers DLR 50WM1552-1557(QUANTUS-IV-Fallturm).

[1] T. Van Zoest et al., Science 328, 1540-1543 (2010).[2] H. Mutinga et al., Phys. Rev. Lett. 110 093602 (2013).


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Confinement-induced effects on the Higgs mode of anultracold Fermi gas after a quench

Simon Hannibal,1, ∗ P. Kettmann,1 M. D. Croitoru,2 V. M. Axt,3 and T. Kuhn1

1Institute of Solid State Theory, Wilhelm-Klemm-Straße 10, 48149 Munster, Germany2Condensed Matter Theory

Groenenborgerlaan 171, 2020 Antwerp, Belgium3Theoretical Physics III

Universitatsstraße 30, 95440 Bayreuth, Germany

Ultracold Fermi gases in optical traps provide a unique system to study the manybody physics of systems composed of fermionic constituents. Both, the BECand the BCS superfluid state are observed in these systems. Furthermore, thetransition between these two states is well controllable by means of a Feshbachresonance, which allows one to tune the interaction strength over a wide rangefrom negative to positive scattering lengths.We employ an inhomogeneous BCS mean field theory and calculate the dynamicsof the BCS gap of a confined ultracold Fermi gas after a quantum quench, i.e., asudden change of the coupling constant. Due to the spontaneously broken U(1)symmetry in the superfluid phase two fundamental modes of the BCS gap evolve,i.e., the amplitude (Higgs) and phase (Goldstone) mode. Here we focus on theHiggs mode on the BCS side of the BCS-BEC crossover regime.We investigate the amplitude dynamics for various excitation magnitudes andanalyze the impact of the harmonic confinement which we take explicitly intoaccount. We find damped collective amplitude oscillations of the gap breakingdown after a certain time [1]. Depending on the quench parameters we investigatethe damping and fragmentation of the Higgs mode exploiting a set of linearizedequations of motions.

[1] S. Hannibal et al., Phys. Rev. A 91, 043630 (2015).


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Critical velocity and counterflow in a Lithium quantum gasexperiment

Shuwei Jin,1, ∗ Marion Delehaye,1 Sebastien Laurent,1

Matthieu Pierce,1 Frederic Chevy,1 and Christophe Salomon1

1Laboratoire Kastler Brossel, ENS-PSL, CNRS,24 rue Lhomond, 75005, Paris, France

In the first part, we study the dynamics of counterflowing bosonic and fermioniclithium atoms. Firstly, by tuning the interaction strength we measure the criticalvelocity vc of the system in the BEC-BCS crossover in the low temperature regimeand we compare the result with the recent prediction of [1]. Secondly, raising thetemperature of the mixture slightly above the superfluid transitions reveals anunexpected phase-locking of the oscillations of the clouds induced by dissipation.In the second part, we present the design and the construction of a second gen-eration lithium experiment dedicated to the studies of fermions in a flat potentialand the search for the exotic FFLO phase.

FIG. 1. The vacuum chamber of the new experiment.

[1] Y. Castin, I. Ferrier-Barbut, and C. Salomon, Comptes Rendus Physique 16 241(2015).

[2] M. Delehaye, S. Laurent, I. Ferrier-Barbut, S. Jin, F. Chevy, and C. Salomon, arxivpreprint, 1510.06709v3.

∗ [email protected]; http://www.lkb.ens.fr/

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All-solid-state laser source at 671 nm for lithium atoms

Stefan Kaiser,1, ∗ Dominik Husmann,1 Sebastian Krinner,1 Martin Lebrat,1

Samuel Haeusler,1 Jean-Philippe Brantut,1 and Tilman Esslinger1

1Department of PhysicsETH Zurich, Otto-Stern-Weg 1, 8093 Zurich, Switzerland

In this master thesis, we design an all-solid-state laser source for cooling andmanipulating atom clouds of 6Li at a wavelength of 671 nm following a design by[1, 2]. In a first step, a pump diode (40 W, 888 nm) pumps a Nd:YVO4 crystalwhich has a strong emission line at 1342 nm. A ring resonator in the bow-tiedesign forces the enhancement of this wavelength. The cavity mirrors are mountedin a specially designed aluminium block such that the laser operation is decoupledfrom any vibrations of the environment. An unidirectional single longitudinalmode operation is ensured by a TGG-crystal inducing a Faraday Rotation, a halfwave plate and two etalons of different thickness. In a second step, the secondharmonic generation will be performed by guiding the laser beam either througha frequency doubling cavity using a ppKTP crystal or through a ridge-waveguidePPLN wavelength conversion module. We expect our design to achieve greateroptical power than schemes based on tapered amplifiers, thus providing strongalternative laser system for realisations such as degenerate Fermi gases and graymolasses.

FIG. 1. Fundamental Laser bow-tie cavity operating at 1342 nm.

[1] U. Eismann et al., Applied Physics B 106, 25 (2011).[2] N. Kretzschmar, Ph.D. thesis, Laboratoire Kastler Brossel (ENS)(2015).

∗ [email protected]; http://www.quantumoptics.ethz.ch

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Goldstone mode in the single-particle dynamics of anultracold BCS Fermi gas after an interaction quench

Peter Kettmann,1, ∗ S. Hannibal,1 M. D. Croitoru,2 V. M. Axt,3 and T. Kuhn1

1Institute of Solid State TheoryWilhelm-Klemm-Straße 10, 48149 Munster, Germany

2Condensed Matter TheoryGroenenborgerlaan 171, 2020 Antwerp, Belgium

3Theoretical Physics IIIUniversitatsstraße 30, 95440 Bayreuth, Germany

Ultracold Fermi gases are a convenient system to probe and study the propertiesof phases like the BEC and the BCS phase and the crossover in between thoseregimes. In particular, ultracold Fermi gases can be used as a test bed to study thetwo fundamental dynamical modes –the Higgs and the Goldstone mode– whichresult from spontaneous symmetry breaking in these phases.We investigate the Goldstone mode in the dynamics of a cigar-shaped ultracold6Li gas after an interaction quench on the BCS side of the BCS-BEC crossover.To this end, we numerically solve Heisenberg’s equations of motion for the Bo-goliubov single-particle excitations in the framework of the Bogoliubov-de Gennesformalism. In doing so, we find that the single-particle occupations oscillate intime with one dominant low-frequency component. We identify this frequencyas the frequency of the Goldstone mode of the BCS gap [1]. Furthermore, weinvestigate the Goldstone mode over a wide range of parameters and show thatthe size-dependent superfluid resonances [2] have a strong impact on this mode.

[1] P. Kettmann et al., arXiv preprint arXiv:1511.04239 (2015).[2] A. Shanenko et al., PRA 86, 033612 (2012).


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Itinerant ferromagnetism in 1D two-component Fermi gases

D.V. Kurlov,1, ∗ F. Schreck,1 Yuzhu Jiang,2

Xi-Wen Guan,2, 3 and G.V. Shlyapnikov1, 2, 4, 5

1Van der Waals-Zeeman Institute, University of AmsterdamScience Park 904, 1098 XH Amsterdam, The Netherlands

2State Key Laboratory of Magnetic Resonance and Atomic and Molecular Physics,Wuhan Institute of Physics and Mathematics, Chinese Academy of Sciences

Wuhan 430071, China3Department of Theoretical Physics,

Research School of Physics and Engineering, Australian National UniversityCanberra ACT 0200, Australia

4Laboratoire de Physique Theorique et Modeles Statistiques, Universite Paris Sud, CNRSOrsay, France

5Russian Quantum CenterNovaya Street 100, Skolkovo, Moscow Region 143025, Russia

We study a one-dimensional two-component atomic Fermi gas with an infiniteintercomponent contact repulsion. It is found that adding an attractive resonantodd-wave interaction breaking the rotational symmetry one can make the groundstate ferromagnetic. A promising system for the observation of this itinerant ferro-magnetic state is a 1D gas of 40K atoms, where 3D s-wave and p-wave Feshbachresonances are very close to each other and the 1D confinement significantlyreduces the inelastic decay.


81

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BECs in the higher modes of a non-degerate cavity

Grigor Kuyumjyan,1, ∗ Deepak Pandey,1 Walid

Cherifi,1 Andrea Bertoldi,1 and Philippe Bouyer1

1LP2N, Universit Bordeaux, IOGS, CNRSTalence, France

Quantum degenerate gases of neutral atoms are excellent system with impor-tant applications in the study of many body quantum physics, condensed mat-ter physics, precision measurements, and quantum information processing. Wedemonstrate the creation of Rubidium-87 Bose-Einstein Condensate(BEC) in anon-degenerate folded cavity in modes TEM00 and TEM01. The cavity reasonantat two wavelengths, =1560nm with a moderat finesse of 2000 and =780nm witha high finesse of 100,000. The cavity is injected at Telecom wavelength 1560nmwhich allow us to trap atoms with dipole force in the center of the cavity furtherthe forced evaporation ramping down the intensity of the beam we obtain a BECin cavity modes by all optical evaporation . In addition, it will provide the pos-sibility to adiabatically load BEC from the fundamental mode TEM00 to highermodes and vice-versa. This will provide the platform to experimentally explorethe interaction dynamics between two or more BECs and will provide a possi-bility to use the system for atom interferometry [1]. The resonance at 780 nmwill be used for cavity aided quantum non-demolition measurements to generatemeasurement induced spin squeezed states [2].

[1] A.D. Cronin , J. Schmiedmayer ,D.E. Pritchard , Rev. MOD. Phys. 81, 1051 (2009).Optics and Interferometry with atoms and molecules.

[2] Z. Chen , J.G. Bohenet , J.M. Weiner , K.C Cox and J. Thomson ,Phys.Rev.A 89043837 (2014). Cavity-aided nondemolition measurements for atom counting andspin squeezing.


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Cavity enhanced atom interferometer for future gravitationalwaves detectors

G. Lefevre,1, ∗ A. Bertoldi,1 B. Canuel,1 S. Pelisson,1

I. Riou,1 P. Bouyer,1 and for the MIGA consortium1Laboratoire de Photonique Numerique et Nanosciences,

Institut d’Optique Graduate School,Rue Francois Mitterand, 33400, Talence, France

After 20 years of development, atom interferometry has become an extremelyperforming probe of accelerations and rotations. Such techniques are now envi-sioned for future gravitational waves detectors to push further the limitations ofstate of the art of optical detectors.In this frame, we are building a new hybrid detector called MIGA (Matter-wavelaser Interferometer Gravitation Antenna) that couples atom and optical interfer-ometry to study the strain tensor of space-time and gravitation at low frequencies.It will consist in a set of three atom (Rubidium) interferometers simultaneouslymanipulated by two 200 m cavity enhanced Bragg pulses using a set of threepulses π

2 -π-π2 . This new detector, which will be installed into the LaboratoireSouterrain a Bas Bruit (LSBB) in Rustrel (France), will benefit of the outstand-ing seismic environment of this low noise underground laboratory and will be atest bench for the detection and monitoring of space-time variation of the localgravity field.With the aim to build a prototype at LP2N in Talence (France), we are workingon an atomic source and 1 m long cavity (Fig. 1). We are currently optimizingthe atomic source and we will realize atom interrogation thanks to the cavityenhanced Bragg pulses.

FIG. 1. Schema of the 1 m cavity enhanced atom interferometer. Atoms are loadedin a 3DMOT using a 2DMOT. After loading they are launched on vertical trajectory,interrogated by Bragg pulses and finally detected.


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A Hybrid Atom-Photon-Superconductor Quantum Interface

Remy Legaie,1, ∗ Craig Picken,1 and J. D. Pritchard1

1University of Strathclyde, Department of Physics107 Rottenrow East, Glasgow G4 0NG, United Kingdom

Quantum mechanics offers a revolutionary approach to how information is pro-cessed, with unprecedented levels of security through quantum encryption andexponential speed up with quantum computing. A key challenge to exploitingthese benefits is the development of the next-generation hardware required forcreating networks exploiting light at the single photon level. Hybrid quantumcomputation overcomes this challenge by combining the unique strengths of dis-parate quantum technologies, enabling realization of a scalable quantum devices.

We present a new project seeking to use cold atoms trapped above supercon-ducting microwave resonators to enable generation, storage and entanglement ofoptical photons on-chip. Strong Rydberg atom dipole-dipole interactions providea mechanism for efficient single photon coupling to atomic ensembles [1], whilstentanglement is mediated via an off-resonant interaction with the superconduct-ing microwave cavity to provide long distance (∼mm scale) interaction lengths[2]. As well as providing an exciting test bed to explore fundamental ideas ofquantum optics, this represents the first steps to the creation of a quantumanalog of a router, an essential building block for quantum networking. Longterm this can be integrated with superconducting qubits technologies to exploitfast on-chip processing power [3].

This work was supported by the EPSRC.

[1] L. H. Pedersen and K. Mølmer, Phys. Rev. A 79, 012320 (2009).[2] D. Petrosyan and M. Fleischhauer, Phys. Rev. Lett. 100, 170501 (2008).[3] J. D. Pritchard et al., Phys. Rev. A 89, 010301(R) (2014).

∗ [email protected]; http://photonics.phys.strath.ac.uk/people/mr-remy-legaie/

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Magnons in Spin-Polarized Quantum Gases

Lauri Lehtonen1, ∗

1Department of Physics and Astronomy,University of Turku, 20014 Turku, Finland

As a gas is cooled down it eventually enters the quantum gas regime. In thisregime it is not necessarily yet quantum degenerate, but may still exhibit theeffects of quantum statistics (Λth > as). Identical Spin Rotation Effect (ISRE)is a phenomenon which becomes pronounced already in this regime. It givesrise to spin waves or magnons, which can be trapped using a magnetic field. Ingeneral their properties depend on temperature, density, quantum statistics, andthe scattering properties of the species. Previously we’ve observed that magnonscan form a Bose-Einstein condensate in spin-polarized atomic hydrogen [1]. Herewe present an analytic solution of the magnon equation for hydrogen, deuterium,tritium, and 3He, allowing the determination of the frequency and lifetime ofmagnons. Whether the magnons are high-field seekers or low-field seekers ispredicted to depend on their temperature, quantum statistics, and scatteringproperties. To this effect an experiment on deuterium is proposed to test theeffect of quantum statistic. Some comments are also made on alkali gases, astheir lower temperature and control of scattering through Feshbach resonancespresent a potentially attractive alternative for ISRE magnon experiments.

FIG. 1. Onset of BEC of Magnons

[1] O. Vainio et al., Phys. Rev. Lett. 114, 125304 (2015).


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PostersA

Design and implementation of fibre-tip Fabry-Perot cavitiesfor controlled atom-photon interactions

Marwan Mohammed,1, ∗ Klara Theophilo,1 Dustin Stuart,1 and Axel Kuhn1

1University of OxfordClarendon Laboratory, Parks Road, Oxford, OX1 3PU, UK

Optical fibre-tip Fabry-Perot cavities [1] can be used for strong coupling of anatom’s electronic state and the cavity’s photon state, allowing for a reversibleand controllable quantum interface. Compared to other Fabry-Perot cavities, thesmall fibre-tip diameter allows optical access with numerical apertures as strongas 0.5, making possible the use of tightly focused dipole traps that hold singleatoms at cavity standing-wave antinodes [2]. We realise confocal fibre cavitieswith two single-mode fibres, with finesses of up to 100,000. We also discusstechnical constraints specific to these cavities, such as mode-matching efficiencyand fibre mirror design.

FIG. 1. Atom-cavity interactions. Tightly-focused dipole traps move atoms intothe cavity field. g, κ and γ represent atom-cavity coupling strength, the decay ratesfrom cavity field to mirrors and from non-cavity field to environment respectively.

[1] D. Hunger et al., New. J. Phys. 12, 065038 (2010).[2] C. Muldoon et al., New. J. Phys. 14 073051 (2012).

∗ [email protected]; http://www2.physics.ox.ac.uk/research/the-atom-photon-connection

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Measurements of spectral function of ultra-cold atoms inspeckle potential

Musawwadah Mukhtar,1, ∗ Vincent Denechaud,1 Valentin

Volchkov,1 Jeremie Richard,1 Alain Aspect,1 and Vincent Josse1

1Laboratoire Charles Fabry, University of Paris-Saclay2 Avenue Augustin Fresnel, 91127 Palaiseau Cedex, France

We present our work on ultra-cold atoms in a spin dependent disordered potentialcreated by a laser speckle. A BEC of 87Rb is initially prepared in a spin state|1〉 insensitive to the disorder and is transferred using a radio-frequency spinflip to state |2〉 which is sensitive to the disorder, as shown in Fig. 1 (left).The disorder amplitude can be tuned from attractive one to repulsive one bychanging the laser speckle’s frequency. From the transfer rate of the atoms,we obtain the spectral function A(E, k) which is equivalent to the probabilityto find an atomic state with a momentum k and energy E in the disorder [1].Such technique has been employed in Fermi gas experiment [2]. We will alsodiscuss two regimes of disorder: the ”classical” disorder where the fluctuations ofthe potential mainly shape the atomic states and the ”quantum” disorder wheretunneling effects between the potential minima play major roles. Finally, we willdiscuss the possibility to produce energy-resolved matter wave states. This workprovides the venue to explore metal-insulator Anderson phase transition in thecondensed matter physics [3].

FIG. 1. Experimental scheme (left) and A(E, k = 0) (right); E = hδRF .

[1] M.I. Trappe et al., J.Phys.A: Math.Theor. 48, 245102 (2015).[2] J.T. Stewart et al., Nature 454, 744 (2008).[3] F. Jendrzejewski et al., Nature Physics 8 5(2012).


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An integrated quantum repeater at telecom wavelength withsingle atoms in optical cavities

Dominik Niemietz,1, ∗ Manuel Uphoff,1 Manuel

Brekenfeld,1 Stephan Ritter,1 and Gerhard Rempe1

1Max-Planck-Institut fur QuantenoptikHans-Kopfermann-Str.1, 85748 Garching, Germany

Quantum repeaters promise to provide a solution to the exponential decreaseof transmission with distance in optical fibers and thus to enable long-distancequantum communication. Past experiments with single atoms in optical cavitieshave underlined the excellent prospects of these physical systems for quantumcommunication. To utilize these properties for the implementation of a quantumrepeater, an efficient interface to photons at telecom wavelengths is necessary.Unfortunately, the ground states of easily laser cooled atoms show no transitionsat telecom wavelengths. We propose an integrated approach for entanglementgeneration between a single atom trapped at the crossing point of two cavitymodes and a single photon at telecom wavelength using a cascaded scheme [1].This eliminates the need for wavelength conversion. We envision entanglementswapping between adjacent atoms to be performed in the same system using acavity-assisted quantum gate. We will present simulations using realistic param-eters with rubidium in optical Fabry-Perot cavities based on CO2 laser-machinedfibers. These show that with current technology it should be possible to im-plement a quantum repeater that can generate heralded entanglement betweenremote nodes faster than using direct transmission.

[1] Uphoff et al., accepted for publication in Appl. Phys. B, arXiv 1507.07849 (2015)


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Bose-Einstein Condensates in an optical lattice: Study of itssignatures

J. Panigrahi,1, ∗ S. Guerin,1 and S. Datta2

1Laboratoire Interdisciplinaire Carnot de BourgogneUniversite Bourgogne Franche-Comte,

9 Av. Alain Savary, BP 47870, 21078 Dijon, France2National Institute of Technology

Rourkela, India

We analyze characteristic signatures of the Bose-Einstein Condensates of an ultra-cold Bose gas on an homogeneous optical lattices at finite temperature. Since thefirst experimental creation of Bose Einstein Condensates(BEC’s) in dilute gases,there have been an incredible proliferation of different quantum systems in whichBEC’s have been achieved [1] [2].Since Ultracold atomic systems in optical lattice is an ideal implementations of theBose-Hubbard model, this system could serve as a quantum simulator to investi-gate condensed matter theories. Thus we first study the BEC’s in non-interactingsystem and introduce the Bose Hubbard Model in an optical lattices, then weapply the Hartee Fock Bogoliubov method with Popov approximation(HFBP)[3]to calculate the excitation properties of the condensates. We first start with theBose Hubbard Hamiltonian and transform it into the momentum space and applythe Bogoliubov approach. We then obtain the condensate density numerically bydiagonalizing the effective Hamiltonian. This formalism combined with local den-sity approximation is applied to characterize a trapped BEC at finite temperatureto calculate the momentum space density and also look into the time of flightimages for the system.

[1] Craig M. Savage, editor. Bose-Einstein Condensation: From Atomic Physics toQuantum Fluids. World Scientific Publishing Company (2001).

[2] Franco Dalfovo, Stefano Giorgini, Lev P. Pitaevskii, and Sandro Stringari. Theory ofbose-einstein condensation in trapped gases. Rev. Mod. Phys. 71, 463512 (1999).

[3] D. van Oosten, P. van der Straten, H. T. C. Stoof, Quantum phases in an opticallattice, Phys. Rev. A 63, 053601 (2001).

[4] G.-D. Lin, Wei Zhang, L.-M. Duan, Characteristics of Bose-Einstein condensation inan optical lattice, Phys. Rev. A 77, 043626 (2008).


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Atomic HongOuMandel experiment∗

M. Perrier,1 A. Imanaliev,1 and P. Dussarat1

1Institut d’Optique2 Avenue Augustin Fresnel, 91127 Palaiseau, France

The Hong, Ou and Mandel (HOM) experiment [1], in which, originally, two pho-tons arriving simultaneously in the input channels of a beam-splitter always emergetogether in one of the output channels, is a milestone of quantum optics. Wereport here the realization of an atomic analog, with Helium, closely following theoriginal protocol, demonstrating successfully the 2-particle quantum interferenceof identical massive particles. The experimental methods and the results will bepresented [2].

FIG. 1. HOM dip in the cross-correlation function. The measurement of the cross-correlation between the output ports as a function of the application time of the atomicbeam splitter exhibits the same dip observed 29 years ago by Hong, Ou and Mandel.

[1] C. K. Hong Z. Y. Ou L. Mandel. Measurement of Subpicosecond Time Intervals be-tween Two Photons by Interference. Physical Review Letters 59, 2044-2046 (1987).

[2] R. Lopes, A. Imanaliev, A. Aspect, M. Cheneau, D. Boiron & C. I. Westbrook. Anatomic Hong-Ou-Mandel experiment. Nature 520, 6668 (2015).


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Extended Bose-Hubbard Models with Ultracold MagneticAtoms

D. Petter,1, ∗ S. Baier,1 M. J. Mark,1, 2 K. Aikawa,1 L.

Chomaz,1, 2 Z. Cai,2 M. Baranov,2 P. Zoller,2, 3 and F. Ferlaino1, 2

1Institut fur Experimentalphysik, Universitat Innsbruck,Technikerstraße 25, 6020 Innsbruck, Austria

2Institut fur Quantenoptik und Quanteninformation,Osterreichische Akademie der Wissenschaften,Technikerstraße 21A, 6020 Innsbruck, Austria

3Institut fur Theoretische Physik, Universitat Innsbruck,Technikerstraße 21A, 6020 Innsbruck, Austria

In a combined effort from experiment and theory, we study strongly magneticerbium atoms loaded into a three-dimensional optical lattice. The combination ofthe dipole-dipole interaction (DDI) between the atoms and the three-dimensionaloptical lattice leads to a system, which is described by an extended Bose-Hubbard(eBH) model [1]. Because of the DDI, the eBH Hamiltonian acquires a verypeculiar anisotropic character, which substantially influences the onsite interactionand reveals density-induced tunneling (DIT) terms. The long-range character ofthe DDI leads to nearest-neighbor interaction (NNI) between two particles onadjacent lattice sites.By means of excitation spectroscopy of the Mott-insulating state and studying thesuperfluid-to-Mott-insulator (SF-to-MI) transition we provide the long-awaitedobservation of the eBH model using ultracold erbium atoms in a short-wavelengthlattice. In particular, we show the tunability of the onsite interaction with the ori-entation of the atomic dipoles and the shape of the single-site Wannier function.Hence, the tunability of the onsite interaction and the DIT allows the system tofavor a SF or a MI state, depending on the orientation of the atomic dipoles.Finally, we also verify the existence of the NNI by applying a dedicated measure-ment scheme of excitation spectroscopy, to confirm that the system is completelydescribed within our eBH model.

[1] S. Baier, M. J. Mark, D. Petter, K. Aikawa, L. Chomaz, Z. Cai, M. Baranov, P.Zoller, F. Ferlaino, preprint, arXiv 1507.03500 (2015).

∗ [email protected]; http://www.erbium.at

91

PostersA

Exploring Quantum Many-Body Systems at the Single-AtomLevel

Antonio Rubio Abadal,1, ∗ Sebastian Hild,1 Johannes Zeiher,1 Simon Hollerith,1

Jae-yoon Choi,1 Tarik Yefsah,1 Immanuel Bloch,1 and Christian Groß1

1Max-Planck-Institute fur QuantenoptikHans-Kopfermann-Str. 1, 85748 Garching, Germany

Ultracold atoms in optical lattices provide an ideal testbed for the study of stronglycorrelated many-body systems. Among the recent progress achieved in the field,the detection and manipulation of single atoms in two-dimensional optical lattices[1, 2] offers a versatile toolbox to investigate condensed matter models. In oursetup we are capable of such control and detection at the single-atom level byfluorescence-imaging of a two-dimensional bosonic gas of Rubidium-87 [2, 3].This has recently allowed for the study of entanglement propagation in a Bose-Hubbard chain [4] or the observation of crystallization in ensembles of ultracoldatoms coupled to Rydberg states [5]. Here we will discuss the main features ofour experiment and summarize recent results.

[1] W. S. Bakr et al., Science 329, 547-550 (2010).[2] J. F. Sherson et al., Nature 467 68-72 (2010).[3] C. Weitenberg et al., Nature 471 319-324 (2011).[4] T. Fukuhara et al., Phys. Rev. Lett. 115 035302 (2015).[5] P. Schauß et al., Science 347 1455-1458 (2015).


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Building a frequency stabilised in-vacuum transfer cavity forcold atoms experiments

Kilian Sandholzer,1, ∗ Andrea Morales,1 Julian Leonard,1

Philip Zupancic,1 Tilman Esslinger,1 and Tobias Donner1

1Institute of QuantumelectronicsOtto-Stern-Weg 1, HPF D4, 8093 Zurich, Switzerland

Our experiment explores exciting new areas in the field of cavity QED by couplingtwo high-finesse (5 ·105 at 780 nm) optical resonators crossing at 60◦ angle, witha 87Rb Bose-Einstein-condensate (BEC). Focus-tunable lenses allow for opticaltransport and size-control on the cloud to spatially overlap the BEC with thecavity modes crossing [1]. The cavities are locked with light at 830 nm andprobed with light at 780 nm supplied by lasers frequency-locked relatively to eachother via a transfer cavity.While the combination of small mode volume and high finesse of our cavitiesensures strong collective coupling between the light field and the atoms, it de-mands also very good relative frequency-stability between the 780 nm and 830nm lasers, with fluctuations far below 100 kHz. This makes the transfer cavityscheme susceptible to any environmental influence (pressure, humidity, temper-ature, vibrations). For typical environmental lab conditions, fluctuations in therelative frequency are estimated to be 113 kHz/mbar air pressure, 370 kHz/◦Cand 70 kHz/10% relative humidity change [2].Our strategy is to ultimately decouple the transfer cavity from all environmentalparameters by using low-expansion materials (Invar), by introducing a vibrationisolation platform, and by operating the transfer cavity under vacuum. The vac-uum is preserved by an ion pump which does not introduce vibrations into thesystem and has a life time above 10 years for sufficiently low pressures. Ourcompact and easily replicable design as well as the high degree of frequency sta-bility should make this transfer cavity system attractive to the whole laser drivenquantum simulation community.

[1] J. Leonard et al., New Journal of Physics 16, 093028 (2014).[2] S. Uetake et al., Applied Physics B 97, 413-419 (2009).

∗ [email protected]; http://www.quantumoptics.ethz.ch

93

PostersA

An experiment to initialize a small Fermi-Hubbard typesystem by lasercooling

Lennart Sobirey,1, ∗ Phillip Wieburg,1 and Henning Moritz1

1Institut fur LaserphysikLuruper Chaussee 149, Building 69; 22761 Hamburg, Germany

Investigating the Fermi-Hubbard model with cold atoms is typically done by fill-ing a large optical lattice with an ultracold Fermi gas. In a new experiment inpreparation in our group, we are planning to use a different approach: A meso-scopic fermionic system is built up site by site using optical microtraps. Eachmicrotrap will contain a single atom cooled to the vibrational ground state byRaman-sideband cooling. This bottom-up approach will provide us with a betterunderstanding of the basic processes governing the Fermi-Hubbard model.In this poster, I will present the general design and some technical aspects of thisnew 40K experiment, which is going to be able to cool a gas of 40K to quantumdegeneracy as well as to directly lasercool single atoms into optical microtraps. Toachieve loading of single atoms with high fidelity, we plan to exploit light-assistedcollisions as described in [1]. The cooling of the atoms will be performed using aRaman-sideband cooling technique similar to the one described in [2]. In order toimage and to manipulate the atoms with high spatial resolution, our setup will beequipped with a novel type achromatic imaging system located inside the vacuumchamber.I will focus particularly on the high current electronics used to realize the flexiblemagnetic fields for magnetic trapping and to provide fields to access Feshbachresonances, as well as the general coil layout of the experiment.

[1] T. Grunzweig, A. Hilliard, M. McGovern and M.F . Andersen, Nature Physics 6 951(2010).

[2] A.M. Kaufman, B.J. Lester and C.A. Regal, Physical Review X 2 041014 (2012).


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Engineering magnetic ordering in optical lattices viaadiabatic cooling of bosons

Araceli Venegas-Gomez1, ∗ and Andrew J. Daley1

1Department of Physics and SUPAUniversity of Strathclyde, Glasgow G4 0NG, Scotland, United Kingdom

The generalised Bose-Hubbard model for two-component bosons on an opticallattice can be used to explore the physics that is associated with a variety ofspin models, where the spin degrees of freedom relate back to the occupation ofbosonic atoms in each lattice site. This is especially true in the limit of stronginteractions, where we can obtain effective spin models with a Heisenberg interac-tion term in second order perturbation theory [1, 2]. Tuning the inter-componentinteractions via Feshbach resonances or adjusting the relative positions of spin-dependent lattices induces different states that can be adiabatically connected[3].When all the interactions are repulsive, i.e. positive, the ground state of theHamiltonian is ferromagnetic. However, via adiabatic state preparation start-ing from a known occupation number of particles per site, other states can berealised. In particular, we study the implementation of a spin-1 model whereattractive interactions between bosonic atoms give rise to antiferromagnetic be-haviour in excited states of the bosonic model [4, 5]. We explore these techniquesin more detail based around parameters of current experiments, looking at themagnetically ordered quantum states that can be realised, and investigating theexperimental timescales for adiabatic cooling, and the robustness of these tech-niques to noise.

[1] A.B. Kuklov et al., Phys. Rev. Letters 90, 100401 (2003).[2] E. Altman et al., New Journal of Physics 5, 113.1-113.19 (2003).[3] J. Schachenmayer et al., Phys. Rev. A, 92 1041602(R) (2015).[4] W. Chen et al., Phys. Rev. B 67, 104401 (2003).[5] A. Sorensen et al., Phys. Rev. A 81, 061603(R) (2010).

∗ [email protected]; http://qoqms.phys.strath.ac.uk/people.html

95

PostersA

Macroscopic excitations in confined Bose-Einsteincondensates, searching for Quantum Turbulence

Roberto Zamora-Zamora,1, ∗ Omar Adame-Arana,1 and Vıctor Romero-Rochın1

1Instituto de FisicaUNAM, 04510 Ciudad de Mexico, Mexico

Currently ultracold atomic gases serve as a new system for study turbulence,carrying new questions to solve. Recent directions for theoretical studies of tur-bulence in Bose Einstein Condensates deal with the problem of dissipation and theeffects of inhomogeneity and finite size, that emerge from consider experimentaltraps. Following our recent work [1], we solve the 3D Gross-Pitaevskii equationwith an initial condition near to ground state. Then we add distinct vortex con-figurations as an excitation and study its dynamics. The results suggest that thissimple system can sustain temporally the Kolmogorov “-5/3” law even withoutan energy dissipation mechanism. Instead of viscous phenomena, we observe viathe excitation spectrum, that after putting energy into the system it respondstransferring kinetic energy to other type excitations inside the system. In thistransient regime, turbulence appears as a mechanism that transfers kinetic en-ergy within the cloud over distinct length scales and distinct excitations (phononsand collective modes). After a period of time, the system reaches a stationarynon-equilibrium state in which clearly turbulent behaviour is not present.

FIG. 1. An example of excitation that can sustain scaling behaviours like Kol-mogorov’s power law.

[1] R. Zamora-Zamora, O. Adame-Arana and V. Romero-Rochın, J. Low. Temp. Phys.180, 109-125 (2015).


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Coherent Single-Photon Transistor mediated by RydbergInteraction

Christian Zimmer,1, ∗ Hannes Gorniaczyk,1 Christoph Tresp,1 Ivan

Mirgorodskiy,1 Asaf Paris-Mandoki,1 and Sebastian Hofferberth1

15. Physikalisches InstitutPfaffenwaldring 57, 70569 Stuttgart, Germany

Mapping the strong interaction between Rydberg excitations in ultracold atomicensembles onto single photons via electromagnetically induced transparency en-ables the realization of optical nonlinearities which can modify light on the levelof individual photons.We report the realization of a free-space single-photon transistor, where a singlegate photon controls the transmission of many source photons [1]. We showthat this transistor can also be operated as a quantum device, where the gateinput state is retrieved from the medium after the transistor operation. Thisforms the basic building block of multi-photon quantum gates and may enablethe non-destructive detection of single photons.We also present our investigation of using electrically tuned Frster resonancesto boost the performance of a Rydberg-mediated single-photon transistor. Weshow that our all-optical detection scheme enables high-resolution spectroscopyof two-state Frster resonances, revealing for example the residual fine-structuresplitting of high-n Rydberg states.

[1] H. Gorniaczyk et al., Phys. Rev. Lett. 113, 053601 (2014).

∗ [email protected]; http://rqo.pi5.physik.uni-stuttgart.de/wordpress/

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Posters: Session B

Poster presentations are divided into two poster sessions, which both take placein the Faculty Club of the TUM Institute for Advanced Study. The pinboardsavailable for the poster session are 88 cm wide and 120 cm high. Therefore, aposter in portrait format is preferred. Please do not exceed A0 poster size. Wewill provide pins/magnets to fix the posters on the walls.

The participants of the session B are:

Name Poster number Name Poster number

Aksu, Serhan Seyyare B99 Lampis, Andreas B112

Becher, Jan Hendrik B100 Lebreuilly, José B113

Borne, Adrien B101 Maiwoeger, Mira B114

Camacho, Arturo B102 Mihm, Moritz B115

Colquhoun, Craig B103 Paul, Daryl B116

Colzi, Giacomo B104 Ramakrishna, Kushal B117

de Hond, Julius B105 Reyes, Ignacio B118

Dehabe, Michael B106 Sbroscia, Matteo B119

Dorier, Vincent B107 Skalmstang, Kristoffer Theis B120

Enesa, Cédric B108 Varguet, Hugo B121

Fischer, Christoph B109 White, Andrew B122

Holland, Naomi B110 Wolf, Philip B123

Lachman, Lukas B111

98

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Mixture of charged and uncharged superfluids in a syntheticmagnetic field

S.Seyyare Aksu1, ∗ and Nader Ghanzanfari1

1Physics Department, Faculty of Sciences and LettersMimar Sinan Fine Arts University, 34380-Sisli, Istanbul,Turkey

In this work, we study the angular momentum transfer in a mixture of two dif-ferent ultracold atomic Bose-Einstein condensates confined in a ring trap. Thesystem is subjected to a synthetic uniform magnetic field along the central axis ofthe ring. We assume that in the presence of a synthetic magnetic field one of thecomponents couples to the magnetic field while the other component does not.One can consider the system as a mixture of two charged and uncharged super-fluids. The ultracold atoms are interacting with each other through short ranges-wave interactions. We demonstrate that if the synthetic magnetic field excitesa circulating superflow in the charged superfluid inter-fluid interactions lead to atransfer of angular momentum to the uncharged one. Thus the superfluid cur-rents appear in both gases. In order to find the momentum transfer from chargedsuperfluid to uncharged one, we write the many-body Hamiltonian of the systemand treat the problem within Bogoliubov-de Gennes approximation. We calcu-late the angular momentum transfer for equal and different particle numbers ofthe condensates and different interaction strengths. We obtain a phase diagramillustrating the stable, phase separated and vortex induced regions as function ofinteraction strength [1–3].

[1] J. Smyrnakis et al., Phys. Rev. Lett. 103, 100404 (2009).[2] D.V. Fil1, and S.I. Shevchenko, Phys. Rev. A 72, 013616 (2005).[3] M. Linn et al., Phys. Rev. A 64, 023602 (2001).

∗ [email protected]; http://msgsufizik.net/

99

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Towards site-resolved single-atom imaging of 6Li atoms in amultiwell potential

Jan Hendrik Becher,1, ∗ Andrea Bergschneider,1 Vincent M. Klinkhamer,1

Simon Murmann,1 Michael Dehabe,1 Gerhard Zurn,1 and Selim Jochim1

1Physikalisches Institut, Heidelberg UniversityIm Neuenheimer Feld 226, 69120 Heidelberg, Germany

In a recent experiment we realized the fundamental building block of the Hubbardmodel by preparing two fermionic 6Li-atoms, one spin up and one spin down, inthe ground state of a double-well potential [1]. By combining many of thesebuilding blocks, we aim for the deterministic preparation of ground-state systemsin multiple wells. To measure correlations in these systems we need a site andspin-resolved imaging technique.In this talk we will report on a site-resolved single-atom imaging setup that werecently added to our experiment. The imaging is conducted far in the Paschen-Back regime, where a closed optical transition exists for each of the two spinstates. We apply two counterpropagating, near resonant laser beams to theatomic sample. Around 14% of the fluorescence photons are collected with ahigh-NA objective and imaged onto an EMCCD camera. By counting the photonsoriginating from each well, we deduce the number of atoms per site.Furthermore, for multiple atoms per well this imaging technique allows us toinvestigate collective effects in the spontaneous emission. We observe a nonlineardependence of the intensity of the fluorescence signal on the total atom numberwhich we interpret in terms of superradiance.

[1] S. Murmann et al., PRL 114 080402 (2015).

∗ [email protected]; http://www.lithium6.de

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Towards a passive photonic quantum memory

Adrien Borne,1, ∗ Serge Rosemblum,1 Orel Bechler,1 Udi Shafir,1 Gabriel

Guendelman,1 Yulia Lovsky,1 Doron Gurovich,1 and Barak Dayan1

1AMOS and Department of Chemical Physics,Weizmann Institute of Science, Rehovot 76100, Israel

In recent years, there has been a tremendous effort towards the realization oflight-matter interactions at the single-photon level that could enable the imple-mentation of a quantum memory [1]. We propose here a scheme that enablesits realization without the requirement of any additional control field. It is basedon our recent experimental demonstration of a single-photon Raman interaction(SPRINT) in which a single photon deterministically toggles the state of a single87Rb atom in a three-level Λ-type configuration [2]. In the present scheme, aqubit encoded as a superposition of the polarization of the incoming photon isdeterministically mapped to a superposition of the two ground states of the atom,as sketch in Fig. 1, effectively performing a SWAP gate between the photonic andatomic states [3]. The readout can be performed by sending a second photon,which would exit at the recorded atomic superposition state. Our experimentalimplementation allows probing the Bloch sphere both in the equatorial plane andalong the poles, and aims at performing a fidelity significantly higher than 2/3 inorder to establish the nonclassical nature of this operation.

𝑒

0 1

𝛾 𝛿

𝛽 𝛼

𝜓 atom = 𝛼 0 + 𝛽 1

𝜓 photon = 𝛾 0 + 𝛿 1

𝑒

0 1

𝛾 𝛿

𝛼 𝛽

𝜓atom = 𝛾 0 + 𝛿 1

𝜓photon = 𝛼 0 + 𝛽 1 𝑎 𝑏

FIG. 1. Schematic of the qubits initially (a) and after SPRINT (b).

[1] H. P. Specht et al., Nature 473, 190193 (2011).[2] I. Shomroni et al., Science 345, 903906 (2014).[3] K. Koshino et al., Phys. Rev. A 82, 010301 (2010).


101

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Superfluidity of a dipolar Fermi gas in a 2D bilayer

Arturo Camacho Guardian1, ∗ and Rosario Paredes Gutierrez1

1Instituto de Fısica, Universidad Nacional Autonoma de Mexico,Apdo. Postal 20-364, Mexico D. F. 01000, Mexico

Ultracold dipolar Fermi molecules lying in 2D optical lattices bilayers are shownto form superfluid phases, both, in the Bardeen, Cooper and Schrieffer (BCS)regime of Cooper pairs, and in the Bose-Einstein condensate (BEC) regime ofbound dimeric molecules. We demonstrate this result using a functional integralscheme within the Ginzburg-Landau theory. We consider molecules with interlayerfinite range s-wave interactions, placed in square optical lattices perpendicularlyaligned to the layers. For the deep Berezinskii-Kosterlitz-Thouless (BKT) phasetransition, we predict critical temperatures around 10nK and 40nK for 23Na40Kand OH molecules, which are within reach of current experiments.

[1] A. Camacho and R. Paredes ArXiv 1505.03811 (2015)[2] A. C. Potter, E. Berg , D. -W. Wang B. I Halperin and E. Demler, Phys. Rev. Lett.

105, 220406 (2010)[3] A. Pikovski , M. Klawunn , G. V. Shlyapnikov and L. Santos, Phys. Rev. Lett. 105,

215302 (2010)

∗ [email protected]; http://www.fisica.unam.mx/ifunam˙english/teorica/index.php

102

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Towards the implementation of quantum probes inspin-dependent optical lattice potentials

Craig Colquhoun,1, ∗ Andrea Di Carli,1 and Elmar Haller1

1Experimental Quantum Optics and Photonics GroupDept. of Physics, SUPA, University of Strathclyde, Glasgow G4 0NG, UK

By means of a small, immersed quantum system (probe) with a reduced numberof degrees of freedom, new insight into global and local properties of a complexquantum system can be provided. Properties such as phase, correlations, andtemperature can change the decoherence and dissipation of the probe dramati-cally, and they can be determined by measuring the dynamics of the probe. I amgoing to report on our progress and future plans to realise such quantum probeswith ultracold Cesium atoms in spin-dependent optical lattice potentials.

∗ [email protected]; http://photonics.phys.strath.ac.uk/mr-craig-colquhoun/

103

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Sub-Doppler cooling of sodium atoms in gray molasses

Giacomo Colzi1, 2, ∗

1INO-CNR BEC Center and Dipartimento di Fisica, Universita di Trentovia Sommarive 14, 38123 Povo, Italy

2Trento Institute for Fundamental Physics and Applications, INFNvia Sommarive 14, 38123 Povo, Italy

We report on the realization of sub-Doppler laser cooling of sodium atoms ingray molasses using the D1 optical transition (3s 2S1/2 → 3p 2P1/2) at 589.8 nm.The technique is applied to samples containing 3× 109 atoms previously cooledto 350 µK in a magneto-optical trap, and it leads to temperatures as low as 9µK and phase-space densities in the range of 10−4. The capture efficiency of thegray molasses is larger than 2/3, and we observe no density-dependent heatingfor densities up to 1011 cm−3.


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Rydberg excitation of ultracold atoms on an atom chip

Julius de Hond,1, ∗ Nataly Cisternas,1 Sindhu Nemarugommula,1

Graham Lochead,1 Robert Spreeuw,1 Ben van

Linden–van den Heuvell,1 and Klaasjan van Druten1

1Van der Waals–Zeeman Instituut, University of AmsterdamScience Park 904, 1098XH, Amsterdam

Rydberg atoms have exaggerated properties, such as very large electrical polar-izabilities and (induced) dipole moments. Because of their strong and tunablelong-range interactions they are now widely being pursued as systems for quan-tum information science [1]. We are performing Rydberg excitation of cloudsof 87Rb atoms magnetically trapped 100 µm from a current-carrying atom chip.Both thermal clouds and Bose–Einstein condensates are used. The clouds havean elongated shape; we are particularly interested in the one-dimensional regime,where the presence of a single Rydberg atom blocks further excitation over the fullradial area. An important aspect is the characterization of the electric field at theposition of the atoms (about 1 V/cm as of now, cf. Figure 1). We are exploringboth resonant excitation and “dressing” ground-state atoms with some Rydbergcharacter, with the goal of studying the resulting correlations and entanglement.

−4 −2 0 2 4 6−15

−10

−5

0

5

Applied field (V/cm)

Res

onan

ce s

hift

(MH

z)

28S1/2 resonance shift vs. applied field

Data

∆ = αE2/2 + offset

FIG. 1. Characterization of the resonance shift with applied field.

[1] M. Saffman, T.G. Walker, and K. Mølmer, Rev. Mod. Phys. 82, 2313 (2010).


105

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The quasi-particle residue in the crossover from few to manyparticles

Michael Dehabe,1, ∗ Andrea Bergschneider,1 Simon Murmann,1 Vincent M.

Klinkhamer,1 Jan-Hendrik Becher,1 Gerhard Zurn,1 and Selim Jochim1

1Physikalisches Institut, Universitat HeidelbergIm Neuenheimer Feld 226, 69120 Heidelberg, Germany

In one dimension, the ground-state wave function of an impurity particle inter-acting with a Fermi sea is orthogonal to the ground-state wave function in thenon-interacting case. Hence, the squared overlap of these two wave functions,which is known as quasi-particle residue, is zero.By measuring the quasi-particle residue of a single impurity atom and an increasingnumber of majority atoms we want to study the emergence of orthogonality in thesystem. We deterministically prepare these few-fermion systems in a cigar-shapedoptical dipole trap in their motional ground state. This system can be consideredas quasi one-dimensional, if the atom number is smaller than the aspect ratioof the trap. For each specific number of majority particles, we determine thequasi-particle residue by flipping the spin of the impurity particle using a resonantradio frequency (RF) pulse and measuring the Rabi frequency.In our current experimental setup, the aspect ratio limits the number of majorityparticles to values smaller than five. We will present our latest results on increasingthe aspect ratio of the trap while keeping full control over the quantum state ofthe few-atom system. This will allow us to study the quasi-particle residue in thecrossover to the many-body limit.

∗ [email protected]; http://ultracold.physi.uni-heidelberg.de/

106

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Quantization of the electromagnetic field in dispersive andlossy media for quantum plasmonics

V. Dorier,1, ∗ D. Dzsotjan,1 H.-R. Jauslin,1 and S. Guerin1

1Laboratoire Interdisciplinaire Carnot de BourgogneUniversite Bourgogne Franche-Comte,

9 Av. Alain Savary, BP 47870, 21078 Dijon, France

The quantization of the electromagnetic field in a passive inhomogeneous linearmagnetodielectric medium has been described in [1]. This can be achieved sincethe Maxwell equations ruling the dynamics of the field can be written as a Hamil-tonian system. The resulting expression of the electric and magnetic observablesas a function of bosonic operators can then be used e.g. to study the propagationof light waves on and through an interface between two passive media [2].As the scientific community shows increasingly interests in the field of plasmonics,we shall extend the quantization procedure to media exhibiting dispersion andlosses. However, this breaks the Hamiltonian structure of Maxwell’s equations.One can work around this problem by expanding the system in a combinationof three Hamiltonian parts [3]: the electromagnetic-field, a harmonic-oscillatorrepresentation of the medium, and the interaction between the two that leads todissipation. This resulting Hamiltonian is then diagonalized by means of Fano’sdiagonalization method [4], and the electric field can be expressed in terms of theclassical Green function.We show how this result can be obtained from a second-quantization procedureonly based upon the macroscopic Maxwell equations. We apply the procedure toderive rigorously effective Hamiltonians for emitter interacting with plasmons ofspherical nanomaterial, which take into account the quantization of the modesemerging from the spherical symmetry. Such models have been used recently inthe strong coupling regime [5, 6].

[1] RJ. Glauber and M. Lewenstein, Phys. Rev. A, 43(1), 467 (1991).[2] CK. Carniglia and RY. Chiao, Phys. Rev. D, 3(2), 280 (1971).[3] TG. Philbin, New J. Phys., 12(12), 123008 (2010).[4] LG. Suttorp and AJ. van Wonderen, EPL, 67(5), 766 (2004).[5] J. Hakami, L. Wang, and M. Suhail Zubairy, Phys. Rev. A, 89(5), 053835 (2014).[6] A. Delga, J. Feist, J. Bravo-Abad, and FJ. Garcia-Vidal, Opt., 16, 114018 (2014).


107

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Towards quantum degenerate Fermi mixtures

Cedric Enesa,1, ∗ Daniel Suchet,1 Michael Rabinovic,1 Thomas

Reimann,1 Christophe Salomon,1 and Frederic Chevy1

1Laboratoire Kastler Brossel24, rue Lhomond 75005 Paris

Since the first realization of a quantum gaz in 1995, intensive research as well asgreat achievements have been made in the field of ultracold atoms. By coolingand trapping an atomic gas, one can observe quantum many-body phenomena atlow enough temperature, when the De Broglie wavelength becomes comparableto the typical distance between particles. At ultralow temperature, the statistics(fermionic or bosonic) of the particle becomes relevant and plays an importantrole. While identical bosons tend to gather in the same quantum state to form aBose-Einstein Condensate while identical fermions, due to Pauli exclusion princi-ple, will form a Fermi Sea.In our experiment, we study a Lithium-Potassium fermionic mixture. Thanks toa dual species magneto-optical trap for the fermionic species 6Li and 40K, het-eronuclear 6Li-40K* molecules have been observed. In order to reach quantumdegeneracy, we successfully cooled down 6Li and 40K below the doppler coolinglimit using a novel three-dimensional gray molasses. Moreover, quantum degen-eracy has already been reached for the 40K.During my presentation at Young Atom Opticians 2016, I will talk about our cur-rent setup as well as our theoretical study to reach double quantum degeneracythanks to evaporative cooling in an optical trap.


108

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Optical Trapping of Ions

C. Fischer,1, ∗ M. Marinelli,1 and J.P. Home1

1Institute for Quantum Electronics, ETH ZurichOtto-Stern-Weg 1, 8093 Zurich, Switzerland

One of the major challenges of simulating quantum systems using ions is thescalability of the trap structure. Linear Paul traps can confine ions only in one-dimensional strings and micro-structured potentials generated by two-dimensionalarrays of rf electrodes are difficult to fabricate using lithographic techniques. Onthe other hand, two- and three-dimensional lattices based on optical potentialsare widely used in neutral atom experiments.Recent work however showed that trapping of ions in tightly focused beams [1–3]is possible and that an ion will also localize in a periodic potential generated bya cavity mode [4].The purpose of our new experiment is to trap not only a single ion but alsotwo-dimensional arrays of atoms and ions at the same time. An isotope selectivemagneto-optical trap will serve as a reservoir of cold 25Mg atoms which will thenbe shuttled into the science chamber containing an optical lattice formed usinga high-finesse build-up cavity. The setup aims to maintain ultra-high vacuumthroughout the experiment and operation of the science chamber at cryogenictemperatures will be desirable to reduce background gas collisions. To increasethe depth of the optical potential and thereby reduce the ion-ion spacing, a build-up cavity will be used, allowing for intra-cavity power of several kilowatts.I will present the recent status of the experiment, along with an outline of thetheoretical considerations which go into the system design.

[1] C. Schneider et al., Nature Photon. 4, 772-775 (2010).[2] M. Enderlein et al., Phys. Rev. Lett. 109, 233004 (2012).[3] T. Huber et al., Nature Comm. 5, 5587 (2014).[4] L. Karpa et al., Phys. Rev. Lett. 111, 163002 (2013).

∗ [email protected]; http://www.tiqi.ethz.ch

109

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Towards holographic dipole traps for the deterministiccoupling of atoms to high finesse optical cavities

Naomi Holland,1, ∗ Dustin Stewart,1 Oliver Barter,1 and Axel Kuhn1

1University of OxfordClarendon Laboratory, Parks Rd, Oxford OX1 3PU

A reliable interface between single photons and atoms is a fundamental componentof most suggested quantum networking schemes. At present, we use such aninterface to single photons with a V-STIRAP process in 87Rb atoms that arestochastically delivered into an optical cavity via an atomic fountain [1]. Whilstthis source provides an excellent testing ground for the photon production, theprobabilistic loading limits its scalability, thus prohibiting experiments that requiremultiple well-coupled atom-cavity systems. Moreover the transit of atoms acrossthe cavity mode results in time-varying coupling strengths, further motivatingthe work presented here to develop techniques for trapping and positioning singleatoms within the mode volume of a cavity.A demonstrated scheme utilising a Digital Mirror Device (DMD) to create holo-graphic dipole traps is examined [2]. This scheme allows for traps tight enoughto take advantage of the collisional blockade regime, but is limited by mirrorringing and heating from mechanical instabilities. The next generation of thisexperiment, using a liquid-crystal phase modulator, is expected to offer improvedstability, less heating, and the capability of moving trapped atoms to arbitrarypositions without losing them. In the long term, this will be integrated withthe fibre-tip cavities currently under construction in our group, with the aim ofpositioning individual atoms into antinodes of the standing wave cavity mode.

[1] P. Nisbet-Jones et al., New Journal of Physics 13, 103036 (2011).[2] D. Stuart et al., arXiv 1409.1841 (2014).

∗ [email protected];

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Nonclassical light from a large number of independentsingle-photon emitters

Lukas Lachman,1, ∗ Lukas Slodicka,1 and Radim Filip1

1Department of Optics, Faculty of Science, Palacky University,17. listopadu 1192/12, 771 46 Olomouc,

Czech Republic

Nonclassical quantum effects gradually reach domains of physics of large systemspreviously considered as purely classical. We have derived a hierarchy of opera-tional criteria suitable for a reliable detection of nonclassicality of light from anarbitrarily large ensemble of independent single-photon emitters. It can be shown,that such large ensemble can always emit nonclassical light without any phasereference and under realistic experimental conditions including incoherent back-ground noise. The nonclassical light from the large ensemble of the emitters canbe witnessed much better than light coming from a single or a few emitters [1].

Detection &

analysis A large ensemble

of single photon emitters

Nonclassicalitycriterion

FIG. 1. The detection of light emerging from a large ensemble of single photonemitters is detected and analysed. An appropriate criterion of nonclassicality canwitness the nonclassical features of the source very reliable.

[1] L. Lachman, L. Slodicka and R. Filip to be published.


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Towards controllable dispersion and gain with cold atoms ina high-finesse ring cavity

Andreas Lampis,1, ∗ Robert Culver,1 Balazs Megyeri,1 and Jon Goldwin1

1School of Physics & Astronomy, University of BirminghamEdgbaston, Birmingham, B15 2TT, UK

We are building an experiment to study the behaviour of cold potassium-39 atomsin a high-finesse ring cavity. The atom-light interactions in our system are in thecollective strong coupling regime, meaning absorbed photons can be re-emittedinto the cavity mode before irreversibly escaping into the environment. Usingelectromagnetically induced transparency (EIT), the group index of refraction ofatomic media can be made extremely large, near-zero or even negative. We havealready shown that applying EIT in a hot potassium vapour cell can generatedeeply sub-natural features leading to group indices up to 6000 [1]. The nextstep is to apply EIT to the cold potassium cloud where we expect even narrowerfeatures and thus higher group indices. This will enable studies of strong in-cavitydispersion and lasing with extreme indices, for applications in active dispersion-enhanced metrology and sensing.

FIG. 1. Picture of the ring cavity from a vacuum chamber’s window. M:mirror.

[1] A. Lampis et al., arXiv 1509.08776 (2015).

∗ [email protected]; http://mpa.ac.uk/muarc/

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Strongly interacting photons in arrays of dissipative nonlinearcavities under a frequency-dependent incoherent pumping

Jose Lebreuilly,1, ∗ Iacopo Carusotto,1 and Michiel Wouters2

1INO-CNR BEC Center and Dipartimento di Fisica,Universita di Trento, I-38123 Povo, Italy

2TQC, Universiteit Antwerpen, Universiteitsplein 1, B-2610 Antwerpen, Belgium

We report a theoretical study of a quantum optical model consisting of an arrayof strongly nonlinear cavities incoherently pumped by an ensemble of population-inverted two-level atoms. Projective methods are used to eliminate the atomicdynamics and write a generalized master equation for the photonic degrees offreedom only, where the frequency-dependence of gain introduces non-Markovianfeatures. In the simplest single cavity configuration, this pumping scheme allowsfor the selective generation of Fock states with a well-defined photon number. Formany cavities in a weakly non-Markovian limit, the non-equilibrium steady staterecovers a Grand-Canonical statistical ensemble at a temperature determined bythe effective atomic linewidth. For a two-cavity system in the strongly nonlinearregime, signatures of a Mott state with one photon per cavity are found.

FIG. 1. Schematic experimental setup : array of nonlinear dissipative cavities, withembedded non markovian two level emitters, pumped in the excited state by anexternal device

[1] J. Lebreuilly et al., arXiv:1502.04016.


113

PostersB

Towards multiple phase measurements of a single pair ofBose-Einstein condensates

Mira Maiwoger,1, ∗ Marie Bonneau,1 Sandrine van Frank,1

Marine Pigneur,1 RuGway Wu,1 and Jorg Schmiedmayer1

1Atominstitut, TU WienStadionallee 2, 1020 Wien, Austria

We propose to experimentally investigate the quantum back-action of phase mea-surements for a pair of Bose-Einstein condensates. On our atomchip based coldatom experiment pairs of BECs are created in radio-frequency dressed double-wellpotentials [1]. Both independent pairs of BECs with no initial phase relation andcoherently split BECs with a well defined relative phase can be prepared on thissetup. The relative phase of a pair of BECs is probed by imaging the expandedand overlapping clouds of atoms in time of flight. A Raman laser system has beenprepared for pulsed output coupling which allows to probe the same cloud of ul-tracold atoms more than once. This provides a tool to investigate the dynamicsof the relative phase of BECs in double-well potentials and allows us to observehow a relative phase between two independent BECs is established by the act ofmeasurement.

[1] T. Berrada et al., Nature Comm. 4, 2077 (2013).

∗ [email protected]; https://tiss.tuwien.ac.at/adressbuch/adressbuch/person/270349

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Zerodur-based optical systems for dual-species atominterferometry in space

Moritz Mihm,1, ∗ Kai Lampmann,1 Andre Wenzlawski,1

Klaus Doringshoff,2 Markus Krutzik,2 Achim Peters,2

Patrick Windpassinger,1 and the QUANTUS-Team3

1Institut fur Physik, Johannes Gutenberg-Universitat Mainz,Staudingerweg 7, 55128 Mainz, Germany

2Insitut fur Physik, Humboldt-Universitat zu Berlin,Newtonstrasse 15, 12489 Berlin, Germany

3LU Hannover, U Hamburg, U Ulm, TU Darmstadt,FBH Berlin, DLR RY Bremen and ZARM at U Bremen

The precision of inertial measurements has been tremendously increased with theadvent of cold atom-based interferometers in recent years. One way to furtherenhance their precision is by measuring in a microgravity environment. Withinthe MAIUS program, three rocket missions performing atom interferometry withBECs in space are scheduled over the next years. An important role for suchexperiments plays the laser system, dedicated to cool and manipulate the atoms.Here, we report on a laser system for dual-species atom interferometry with Rband K providing light for a 2D/3D-MOT and interferometry. Core elements ofthe laser system are optical benches and fiber-optical elements used on the onehand to distribute, overlap and switch the laser beams and on the other hand tostabilize the laser frequencies. In order to withstand the harsh conditions duringflight, we use the glass ceramic Zerodur providing high mechanical and thermalstability [H. Duncker et al., Appl. Opt. 53, 4468-4474 (2014)]. All free-spaceoptical components are glued on Zerodur-boards using light-curing adhesives.The boards are connected via fibers.Comprising all integral parts, a test bench for the qualification of components hasbeen assembled, characterized and tested under flight conditions in a shaker testfacility. In the next step, the flight hardware will be built and characterized priorto integration.The MAIUS project is supported by the German Space Agency DLR with fundsprovided by the Federal Ministry for Economic Affairs and Energy (BMWi) undergrant number 50 WP 1433.

∗ [email protected]; https://www.qoqi.physik.uni-mainz.de/

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Towards spinor BEC in extremely low magnetic fieldenvironments

Daryl Paul,1, ∗ Daniel Benedicto-Orenes,1 Anna

Kowalczyk,1 Mark Brannan,1 and Kai Bongs1

1School of Physics and Astronomy, University of BirminghamEdgbaston, B15 2TU, Birmingham, UK

Optical trapping of ultracold atoms provides the opportunity to capture atomspopulating several spin states. A spinor Bose-Einstein condensate of 87Rb in anoptical lattice serves as a quantum simulator, allowing rich insight into the phe-nomenology of quantum magnetism. We present progress towards achieving sucha condensate in a novel setup, whereby the condensate is heavily shielded fromexternal magnetic fields. Several layers of passive mu-metal shielding, and activecompensation with electronic feedback will be used to supress the field to be-low 1nT, such that the linear Zeeman shift is small compared to the interatomicinteraction. This will allow the investigation of the magnetic dipole-dipole inter-actions, giving access to the static and dynamical properties of the system undernovel experimental conditions.

∗ [email protected]; http://www.birmingham.ac.uk/research/activity/physics/quantum/coldatoms/index.aspx

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Strongly interacting photons using slow light rydbergpolaritons

Kushal Ramakrishna,1, ∗ Przemyslaw Bienias,1 and Dr.Hans Peter Buchler1

1Institut fur theoretische Physik III, Universitat StuttgartPfaffenwaldring 57, 70550 Stuttgart, Germany

Rydberg atoms have hydrogenlike behavior associated with them at large princi-pal quantum number along with tunable large dipole moment and polarizability.The blockade phenomena results in effectively having a singe Rydberg excitationin an ensemble due to the energy shift of the strong Van der Waals interactionbetween atoms defined by blockade radius. The demonstration of Electromagnet-ically induced transparency (EIT) has resulted in slow light propagation in atomicmedia. Photons normally do not interact among themselves although they canbe made to interact in a non-linear medium. Under the conditions of EIT, Ryd-berg media forms a superposition of strongly interacting light-matter componentsas Rydberg polaritons. Furthermore, the eigenmodes evolve as Bright and Darkstate polaritons. Under certain regimes and conditions, bound and scatteringstates of polaritons has been demonstrated. The many-body interactions can bewell understood in terms of low-energy scattering theory and the appearancesof Resonances. We identify the scattering properties of the Rydberg polaritons.[1–3].

[1] P. Bienias et al., Phys. Rev. A. 90, 053804 (2014).[2] M. Fleischhauer et al., Rev. Mod. Phys. 77, 633–673 (2005).[3] M.F. Maghrebi et al., Phys. Rev. Lett. 115, 123601 (2015).

∗ [email protected]; http://www.itp3.uni-stuttgart.de

117

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Phase transitions in Bose-Einstein condesates

Ignacio Reyes Ayala,1, ∗ V. Romero-Rochin,1 J.

Seman-Harutinian,1 and F. J. Poveda-Cuevas1

1Institute of PhysicsUniversidad Autonoma de Mexico, Distrito Federal, Mexico

We study phase transitions in Bose-Einstein condensates using a theoretical modeland we developed a technique to study experimental images of BECs to comparewith our model. This model consist of building a chemical potential that approxi-mates the data obtained from experimental images. Using this chemical potentialwe apply the local density approximation to built the density in function of theposition (ρ(x, y, z)) for different potentials (V (x, y, z)). From ρ(x, y, z) we canget the global variables and to study the thermodynamics of the system [1, 2].

[1] N. Sandoval-Figueroa and V. Romero-Rochin, Phys. Rev. E 78, 061129 (2008).[2] V. Romero-Rochin, Phis. Rev. Lett. 94 130601 (2005).


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Towards quantum gases in novel optical lattice geometries

Oliver Brix,1 Matteo Sbroscia,1, ∗ Konrad Viebahn,1

Hendrik Von Raven,1 and Ulrich Schneider1

1Cavendish Laboratory, University of CambridgeJJ Thomson Avenue, CB3 0HE Cambridge, UK

When matter is cooled down to temperatures approaching 0 Kelvin, quantum me-chanics completely dominates its behaviour and gives rise to novel effects such assuperfluidity and Bose-Einstein condensation. In our new experimental apparatus,soon to be completed, the atoms (87-Rb, 39-K or 40-K, i.e. both fermions andbosons) will to be trapped with the aid of a three-dimensional magneto-opticaltrap (3D MOT) and passed through several steps of cooling to reach nanoKelvintemperatures. In order to efficiently load each atomic species into the 3D-MOT,two independent two-dimensional MOTs are included in the setup: this allowsfor a large number of trapped atoms, therefore enabling optimisation of otherfeatures of the experiment, such as its cycle speed. This will also benefit froma newly designed coil configuration for the magnetic fields used both to trans-port the trapped atomic cloud from the 3D-MOT to the experiment cell. Theatoms will then be irradiated with optical lattices of desired spatial and temporalprofile in order to perform experiments on novel states of matter and the out-of-equilibrium dynamics of interacting quantum many-body systems. Exampleof the novel lattice geometries to be tested are the Lieb and Kagome lattices,and quasiperiodic lattices. The interplay between flat bands and fractal spectra,strong correlations and topological features will be investigated.

∗ [email protected]; http://www.manybody.phy.cam.ac.uk

119

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Towards the Bose Polaron in an ultracold gas

Kristoffer Theis Skalmstang,1, ∗ Nils B. Jørgensen,1 Lars Wacker,1

Rasmus S. Christensen,1 Georg Bruun,1 and Jan Arlt1

1Department of Physics and Astronomy, University of AarhusNy Munkegade 120, 8000 Aarhus C, Denmark

An impurity interacting with its surroundings leads to the formation of a quasiparticle, called a polaron. In 1933 Landau first described the polaron, formedin a solid by the interaction between the electron and the lattice displacements,described as a bosonic phonon gas. Ultracold gases with their high degree ofcontrol are a perfect test bench to study such impurity systems. First experimentalinvestigations of the Fermi polaron have already been achieved in ultracold Fermigases. [1–3].Likewise, bosonic polarons can be investigated using mixtures of ultracold bosonicgases. I will present our study of the Bose polaron, where we employ magneticFeshbach resonances to tune the interaction between two spin states of 39K. Werecord the energy spectrum of the impurity at different interaction strengths, al-lowing us to distinguish between the mean field energy regime and the appearanceof the polaronic signature in the spectrum.

[1] A. Schirotzek et al., Phys. Rev. Lett. 102, 230402 (2009).[2] C. Kohstall et al., Nature, 485, 615618 (2012).[3] M. Koschorreck et al., Nature, 485, 619–622 (2012).

∗ [email protected]; http://phys.au.dk/forskning/forskningsomraader/uqgg0/

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Modes hybridization in a strongly coupled metalnanoparticle-quantum emitter system

Hugo Varguet,1, ∗ Benjamin Rousseaux,1 David Dszotjan,1 Gerard

Colas des Francs,1 Hans-Rudolf Jauslin,1 and Stephane Guerin1

1Laboratoire Interdisciplinaire Carnot de Bourgogne, UMR 5209 CNRSUniversite de Bourgogne, 9 Avenue Alain Savary,

BP 47 870, F-21078 DIJON Cedex, France

The quantum control of atoms is a key issue for quantum information processing orrealization of optical logical gates. This generally necessitates the strong couplingof atoms to a high Q-cavity for efficient manipulation of the atoms dynamics(cavity quantum electrodynamics or cQED). Since almost a decade, strong effortsare put to transpose cQED concepts to plasmonics in order to profit of the strongmode confinement of surface plasmons polaritons [1].In this work, we derive an effective hamiltonian [2] that describes the metallicnanoparticle-emitter coupling in full analogy with cQED. We explicitely discussthe mode hybridization in the strong coupling regime offering a simple and exactunderstanding of the energy exchange.

2.8 2.9 3 3.1

P(ω

)

hω (eV)

FIG. 1. Left) Energy diagram of the atom-metallic nanoparticle hybridized system.Right) Polarization spectrum in the strong coupling regime.

[1] M.S. Tame, K.R. McEnery, S.K. Ozdemir, J. Lee, S.A. Maier, and M.S. Kim, NaturePhysics 9, 329-340 (2013)

[2] B. Rousseaux, D. Dzsotjan, G. Colas des Francs, H.R. Jauslin, C. Couteau, and S.Guerin; Adiabatic passage mediated by plasmons: a route towards a decoherence-freequantum plasmonic platform, Submitted.


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Simulating Noise Assisted Quantum Transport with theInternal States of Cold Atoms

Andrew White,1, ∗ Chris Gill,1 Plamen Petrov,1 and Vincent Boyer1

1Cold AtomsSchool of Physics and Astronomy,

University of Birmingham, B15 2TT, United Kingdom

Understanding and measuring the rate of quantum decoherence in the presence ofnoise is vital in developing our understanding of the mechanism of noise assistedquantum transport in processes such as photosynthesis [1]. The project aimsto investigate the rate of depolarisation and to characterise the effect of noiseexperimentally on transport between different coupled mf states in a cold atomssystem, this serves as a basic simulator of biological exciton transport [2].

FIG. 1. The internal states within the atom (left) are prepared by acting an mag-netic field on the atoms that lifts the degeneracy of the mf states. The statesare coupled together using an RF field and a Raman transition, this simulates theexciton transport within a biological network (right).

The noise is introduced by perturbing the magnetic field acting on the atoms,effectively ”shaking” the energy separation of the mf states. The rate at whichdecoherence occurs can be used to characterise the effect of noise on the system.This poster will describe the experimental set-up required for investigating noiseassisted quantum transport.

[1] M. Mohseni et al., J. Chem. Phys. 129, 174106 (2008).[2] P. Rebentrost et al., New Journal of Physics. 11, 033003 (2009).

∗ [email protected]; www.birmingham.ac.uk/cold-atoms

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Radiation trapping in hot rubidium vapour

Philip Wolf,1, ∗ Sebastian Slama,1 and Claus Zimmermann1

1Physikalisches InstitutAuf der Morgenstelle 14, 72076 Tbingen, Germany

Imprisonment of resonance radiation is a fundamental physical phenomenon whichalways occurs when light interacts with matter [1]. In my master’s thesis weinvestigate the radiative decay rate of rubidium atoms in dense atomic vapourusing time-domain fluorescence. The detector consists of a single mode fibertip, observing radiation trapping effects in a very small detection volume. Theexperimental results were compared to a Monte-Carlo simulation with a goodquantitative agreement between experiment and Simulation. For the future weplan to observe coherent dynamics such cooperative decay and superradiance [2].

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FIG. 1. The red circles show the mean number of scattering events of the measureddata, plotted against density. A comparison with a Monte-Carlo simulation (bluecrosses) gives a good quantitative agreement.

[1] Keaveney, James. Collective Atom-Light Interactions in Dense Atomic Vapours.Springer, 2014.

[2] Kwong, Chang Chi, et al. ”Cooperative emission of a coherent superflash of light.”Physical review letters 113.22 (2014): 223601.


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Additional information

TalksSpeakers can use their own laptops for the presentation or copy their talk ontothe provided notebook in good time before the start of the session. In any case,correct projection of the presentation should be tested prior to the session.

Please plan your talk according to the schedule.Invited talks: 50 min. + 10 min. discussionContributed talks: 15 min. + 5 min. discussion

Poster presentationsPoster presentations are divided into two poster sessions, which both take placein the Faculty Club of the TUM Institute for Advanced Study. The pinboardsavailable for the poster session are 88 cm wide and 120 cm high. Therefore, aposter in portrait format is preferred. Please do not exceed A0 poster size. Wewill provide pins/magnets to fix the posters on the walls.

There will be prizes for the best posters.

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Hotel Ibis München City NordAccommodation. All participants are accommodated in Hotel Ibis München CityNord in double/twin rooms from Sunday 21st evening to Friday 26th morning (5nights) with breakfast included. You can check in on Sunday earliest at 3 pm, andhave to check out on Friday before 12 pm.

Address: Ibis München City Nord, Ungererstr. 139, 80805 Münchenhttp://www.accorhotels.com/de/hotel-0996-ibis-muenchen-city-nord/index.shtml

How to get there (From Munich main station). Once arrived at the centraltrain station, any suburban train (S-Bahn) towards the east (direction Ostbahn-hof ) will take you to Marienplatz. From there take the metro line 6 (U6) towardsGarching-Forschungszentrum or Fröttmaning. The hotel is located 300 m north ofthe stop Nordfriedhof at Ungererstraße.

How to get there (From Munich airport). Take the Lufthansa Airport Busdirectly from one of the terminals to the bus stop Munich North (close to Nord-friedhof ) which is next to the hotel. The ride takes 30 minutes and costs 10.50EUR for a single journey and 17 EUR for a return ticket. Alternatively, you cantake the suburban train 8 (S-Bahn S8), change at Marienplatz and go from thereto Nordfriedhof with metro line 6 (U6). This route takes about 1h.

To the conference at Institute for Advanced Study (IAS), Garching rese-arch campus. From the city center or the hotel next to metro station Nordfriedhof,take metro line 6 (U6) towards Garching-Forschungszentrum (end of the line).The IAS is located close to the station Garching-Forschungszentrum (north exit).

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The campus Garching

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U6 Garching-Forschungszentrum

At campus Garching a large part of the the Technical University of Munich (buil-dings in blue) is located. On the same site, there are also several Max PlanckInstitutes (red), external institutions (yellow) and a few LMU buildings (green).The scientific part of the conference will take place on the campus. Upon arrivalwith the metro you will find yourself in the centre of the campus, with the Institutefor Advanced Studies (IAS) located north of the metro station. The modernbuilding is directly visible from the northern exit. Here, the talks, coffee breaks,and poster sessions will take place.

In the far south of the campus the Max Planck Institute of Quantum Optics(MPQ) can be found where lab tours will be given on Monday afternoon.

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Conference venue

TUM Institute for Advanced Study (IAS)

All talks and poster sessions will take place in the Institute for Advanced Study(IAS) on the TUM campus in Garching. Coffee, snacks and drinks are availableduring the breaks. The breaks and poster sessions take place in the Faculty Clublocated in the top floor of the building.

LunchDaily lunch is included in the conference fee and will be offered at the canteen ofthe Max Planck Institute of Plasma Physics (IPP, see campus map). On the firstday we will guide you there. The area is private property and you might be askedto show your conference name tag upon entry.

The lunch vouchers included in the conference package cover 8 EUR each whichshould be enough for a good lunch. Anything beyond 8 EUR is at your ownexpense. The canteen offers at least four different dishes (at least one vegetarian)starting from 2.95 EUR as well as a salad bar.

If you prefer to eat somewhere else, there are several places to get food on campus.Close to the IAS there is the main university dining hall (Mensa). To eat here oneneeds to get a prepaid card, however, on the top level of the dining hall there isalso a smaller canteen where you can pay cash. Most of the bigger buildings on thecampus, such as the chemistry department (north), the engineering department(besides the metro station), and the math department (south) also have their owncafeterias. There is also a small bakery and an Asian and Bavarian fast food place

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located at the southern exit of the metro.

Dinner is not included in the conference fee and it is hard to find eating options oncampus after 6 pm. It is therefore recommended to have dinner in Munich. Thereare also a few dining options in the city of Garching (Bavarian, Italian, Greek,Indian food).

WifiThere is wifi in all university buildings as well as in some public places of the cityof Munich.

EduroamUse the Eduroam access provided by your institution, if you have this option. Ifyou have set it up correctly, your device will probably connect automatically.

Alternative accessIf Eduroam does not work for you, use the temporary YAO access:

Wifi name (SSID): mwn-events

User name:

Password:

The access is available until February 26, 4 pm.

To view configuration profiles and instructions for setting up your device scan theQR code or go to https://www.lrz.de/wlan and click mwn-events. In universitybuildings this link can be accessed via the open network with the name (SSID)“lrz”.

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Social events

Welcome receptionMeet your fellow YAO 2016 participants for a drink at the Welcome Reception onSunday at 7 pm. It is held at the Vorhoelzer Forum on top of the main buildingof TU Munich. We thank Menlo Systems for sponsoring this event.

To get there from the hotel take the metro line 6 (U6) from Nordfriedhof andget off at Sendlinger Tor. There, change to U2 and get off at Theresienstraße.Walking eastward for about 300 m you will find yourself in between universitybuildings of the TU Munich. Head another 100m south on Arcisstraße for themain entrance. Inside the building walk the first corridor to the left then takeeither the stairs or the elevator to the 5th floor. There are also indications insidethe building showing the way to the Vorhoelzer forum. Be aware that usually themain entrance doors are closed on Sundays, however, passing the porter’s officeto your right you can always enter. You can also meet the organizers in the hotellobby at 18.15 pm to head to the venue together.

Main building of TU Munich

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City tourThursday afternoon you can join a city tour of the historic centre of Munich. Thetour will start at 4 pm at the Fischbrunnen (fish fountain) located in front ofthe city hall at Marienplatz. To get there take metro line 6 (U6) from Garching-Forschungszentrum and get off at Marienplatz. As the last talk on Thursday endsat 3 pm and the ride takes about 26 minutes you will arrive on time with eitherthe train leaving at 3.16 pm or 3.26 pm.

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Conference dinnerAfter the city tour you will have time to explore the centre of Munich on your ownor go back to the hotel. The conference dinner will start at 7.30 pm on Thursdayevening and is held at Augustiner Klosterwirt, a typical Bavarian restaurant. Toget there from the hotel take the metro to Marienplatz and walk towards thewest along Kaufingerstraße. Enter one of the 4 streets to the right to get to theprominent Frauenkirche, Munich’s cathedral. In front of the church’s main entranceyou find the Augustiner Klosterwirt (address: Augustinerstraße 1). Reserve about20 to 25 minutes for the journey from the hotel. If you do not want to go thereon your own, meet the organizers at 7 pm in the hotel lobby to go there together.

Frauenkirche Eisbach

The English Garden in winter BMW World near Olympiapark

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Munich during the day – sightseeing and culturalgoodiesFrauenkirche / Cathedral of Our Dear Lady: A plainly designed 15th century

church in gothic style.

Schloss Nymphenburg / Nymphenburg Palace: A 17th century castle with areally beautiful and carefully designed garden.

Deutsches Museum / German Museum: A museum focusing on technologyand science. There are 28.000 objects from 50 different fields includingAerospace, Computers, Physics and much more. The exhibition of historicreal size trains combined with one of Germany’s biggest model train setswill make the German Museum one of Sheldon Cooper’s favorite places (4EUR for students, 11 EUR regular entry).

Pinakotheken: These museums are dedicated to paintings. There are three flavors:In the “old” Pinakothek art from before the 19th century is exhibited. ThePinakothek of “modern times” shows paintings from the 20th century whileyou find everything in between in the “new” Pinakothek (Prices between 2and 7 EUR for students).

Lehnbachhaus: Another art gallery which is mostly famous for the collection ofpaintings from a group of artist known as “Der Blaue Reiter” (The BlueRider, early 20th century expressionism).

Hofbräuhaus: Munich’s most famous beer hall. This is a favorite of many touristsand definitely worth a visit once.

English Garden: Munich’s biggest park area. More appealing in the summer butif you look for a nice walk you should consider the English garden or theNymphenburg palace.

The Residence: The biggest palace within the city.

Olympiapark: This park area was constructed for the 1972 Olympic Games andis worth a visit because of its outstanding architecture. The brave can climbthe roof of the Olympic stadium.

Allianz Arena: A really modern football arena you can see on your way toGarching.

BMW World: A must see for automobile enthusiasts. Entrance is free and it isopen until midnight.

More information on: www.muenchen.de/int/en.html

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Munich at night

Munich has a very lively nightlife and it is impossible to account for all the differentbars, restaurants, and clubs here. We have therefore limited ourselves to statecertain areas where a great number of places to go out at night can be found.This list is by no means complete.Feel free to check out other options. The following web pages might help:www.muenchen.de, www.sz.de/muenchen, or www.muenchen-geht-raus.de. Notethat only limited information is available in English.

Münchner Freiheit

To the east of the station Münchner Freiheit, easily reached from either the TUMcampus or the hotel, many bars and restaurants can be found, some offeringvery cheap prices for Munich standards. This area is also a very good place forpeople looking for a midnight snack such as a kebap. Places to mention include:Barschwein (bar), Drugstore (restaurant/bar), Trumpf oder Kritisch (bavarianbar), Schabinger 7 (bar), Hopfendolde (bar) and riva bar.

Centre

Around the centre (metro station Marienplatz) not too many bars can be found,however, the typical Bavarian restaurants located in this area offer good food aswell as good beer. Afterwards, a good idea might be to check out the Irish pubKillians, the casual Favoritbar, or Jaded Monkey for the not-so-casual cocktail.There are many clubs to the west of the centre along Sonnenstraße (reachable viathe metro stations Stachus or Sendlinger Tor). These range from rather posh andexpensive places such as Pacha, 089 bar or Call me Drella (beware, the doorcan be hard in Munich) to the opposite in form of techno clubs open till early inthe morning like Rote Sonne and Harry Klein.

Gärtnerplatz

Around the beautiful Gärtnerplatz (close to the metro station Frauenhoferstraße)in the notorious Glockenbachviertel a great variety of bars can be found. Mostplaces are not very posh and offer their own unique charm. The high density ofbars makes this area ideal for bar hopping. Before going home in the night don’tforget to pick up a Currywurst at Bergwolf (located directly besides the metrostation Frauenhoferstraße).

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UniversitätAlso worth mentioning is the area around and between Munich’s two main universi-ties. To get here just leave the metro at Universität and stroll along Schellingstraßeand Theresienstraße and enter whichever place suits your fancy. For traditionalBavarian eating Alter Simpl as well as Atzinger can be recommended. But thereis also a lot of international food available from Italian restaurants over “Mexican”food in Sausalitos to Chinese food in LeDu Happy Dumplings. With a filledbelly you can continue on to some of the numerous bars in the area as for examplethe Stammbar where you pour your own beer or maybe the always packed Schall& Rauch.

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Public transportThe MVV pass that you got with your welcome bag is valid in the centre ofMunich (Innenraum) and for the journey to the campus in Garching for 7 daysstarting from Sunday. You cannot go to the airport using only this week pass.

Ammer-see

StarnbergerSee

3

3Amalien-burgstr.

Roman-platz

Leonrodpl.

Ostfriedhof

TegernseerLandstr.

GroßhesseloherBrücke

HochschuleMünchen

Max-monument

(KlinikumBogenhausen)

Wörthstr.

Nordbad Kurfürsten-pl.

Gondrellplatz

Schwan-seestr.

Effnerplatz

St. Emmeram

SchwabingNord

St.-Veit-Str.

Grünwald

X30

X30

X30

X30

X30

X30

3

3

U8

U8

MVV / Stand: Dezember 2015

München XXLInnenraum

Außenraum

Tarifzonen

Schnellbahnnetzmit Tram und ExpressBus

ExpressBus

Tram

Regional- / Fernzughalt

Mo-Sa tagsüber bis ca. 22 UhrSo&Feiertage kein Betrieb

AbschnittOstbahnhof - Ebersberg

v v

U8S6

Nur zeitweilig

Mammendorf

Malching

Maisach

Gernlinden

Esting

Olching

Gröbenzell

Lochhausen

Langwied PasingLaim Donnersberger-Hirsch-

garten brückeHacker-brücke

HauptbahnhofCentral Station

Karlsplatz(Stachus)

Marienplatz IsartorRosenheimerPlatz Ostbahnhof

Altomünster

Kleinberghofen

Erdweg

Arnbach

Markt Indersdorf

Niederroth

Schwabhausen

Bachern DachauStadt

Petershausen

Vierkirchen-Esterhofen

Röhrmoos

Heberts-hausen

Dachau

Karlsfeld

Allach

Untermenzing

Obermenzing

FreisingPulling

NeufahrnEchingLohhofUnter-schleißheim

Ober-schleißheim

Feldmoching

Fasanerie

Moosach

Flughafen MünchenMunich Airport

Flughafen Besucherpark

Hallbergmoos

Ismaning

Unterföhring

Johanneskirchen

Englschalking

Daglfing

Erding

Altenerding

Aufhausen

St. Koloman

Ottenhofen

Markt Schwaben

Poing

Grub

Heimstetten

Feldkirchen

Riem

Berg am Laim

Leuchtenberg-ring

Trudering

Gronsdorf

Haar

Vaterstetten

Baldham

Zorneding

Eglharting

Kirchseeon

GrafingBahnhof

GrafingStadt

Ebersberg

St.-Martin-Str.

Giesing

Perlach

Neubiberg

Ottobrunn

Hohenbrunn

Wächterhof

Höhenkirchen-Siegertsbrunn

Dürrnhaar

Aying

Peiß

Großhelfendorf

Kreuzstraße

Fasangarten

Fasanenpark

Unterhaching

Taufkirchen

Furth

Deisenhofen

Sauerlach

Otterfing

Holzkirchen

Heimeran-platz

Harras

Mittersendling

Siemenswerke

Solln

Großhesselohe Isartalbf.

Pullach

Höllriegelskreuth

Buchenhain

Baierbrunn

Hohenschäftlarn

Ebenhausen-Schäftlarn

Icking

Wolfratshausen

Westkreuz

Lochham

Gräfelfing

Planegg

Stockdorf

Gauting

StarnbergNord

Starnberg

Possen-hofen

Feldafing

Tutzing

Neuaubing

Harthaus

Freiham

Germering-Unterpfaffenhofen

Geisenbrunn

Gilching-Argelsried

Neugilching

Weßling

Steinebach

Seefeld-Hechendorf

Herrsching

Leienfelsstr.Aubing

Puchheim

Eichenau

Fürsten-feldbruck

Buchenau

Schön-geising

Grafrath

Türkenfeld

Geltendorf

Hasenbergl Dülferstr. Harthof Am Hart

MoosacherSt.-Martins-

PlatzOber-

wiesenfeldPetuel-ring

Georg-Brauchle-Ring

Gern

Rotkreuz-platz

Maillinger-str.

Stiglmaier-platz

FrankfurterRing

Milberts-hofen

PlatzBonner

Scheidplatz

Hohenzollernplatz

Josephsplatz

Theresienstr.

Königsplatz

Garching-ForschungszentrumGarching

Garching-Hochbrück

Fröttmaning

KieferngartenFreimann

Studentenstadt

Alte Heide

Nordfriedhof

Dietlindenstr.

MünchnerFreiheit

Giselastr.

Universität

Lehel

Max-Weber-Pl.

Richard-Strauss-Str.

Böhmerwaldplatz

Prinzregentenplatz

FriedenheimerStr.

Partnach-platzWestparkHolzapfel-

kreuthHaderner

Stern

Groß-hadern

Aidenbachstr.Machtlfinger

Str.

ForstenriederAllee

Basler Str.

Theresienwiese

Schwanthaler-höhe

Obersendling

Thalkirchen (Tierpark)

Brudermühlstr.

Implerstr. Poccistr. GoetheplatzFraunhoferstr.

Kolumbus-platz

Silberhorn-str.

Untersberg-str.

Candid-platz

Wettersteinplatz

St.-Quirin-Platz

Karl-Preis-Platz

Innsbrucker Ring

Michaelibad

Quiddestraße

Therese-Giehse-Allee

Kreillerstr.Josephs-

burg

Moos-feld

MessestadtWest

Olympia-Einkaufs-zentrum

Neuperlach Süd

Olympia-zentrum

Westfriedhof Arabellapark

Laimer PlatzWestend-

str.

KlinikumGroßhadern

FürstenriedWest

SendlingerTor

Mangfallplatz

Neuperlach Zentrum

MessestadtOst

Odeonsplatz

S2

S4

S7

S6

U2

U5

S8

U4

U4

U7

U3

U7U1

U5

U5

U1

S3

S4

S8

S20

U6

U6

S3

U3

S6

S7

U2

U8

S1

S2

U3

U2

20

12

16

1718

16 17

18 19

19 19

1525

27

28

18

16

21

134

Info

If you leave Munich from the airport until Sunday, February 28, 12 am and donot plan to take the bus, you can use your week pass together with a Single-Tageskarte Außenraum (single ticket outer area, one person, 6.40 EUR) or aGruppen-Tageskarte Außenraum (group ticket outer area, up to 5 persons, 12.20EUR). A single journey from or to the airport by train (S-Bahn) costs 10.80 EUR.

Ammer-see

StarnbergerSee

3

3Amalien-burgstr.

Roman-platz

Leonrodpl.

Ostfriedhof

TegernseerLandstr.

GroßhesseloherBrücke

HochschuleMünchen

Max-monument

(KlinikumBogenhausen)

Wörthstr.

Nordbad Kurfürsten-pl.

Gondrellplatz

Schwan-seestr.

Effnerplatz

St. Emmeram

SchwabingNord

St.-Veit-Str.

Grünwald

X30

X30

X30

X30

X30

X30

3

3

U8

U8

MVV / Stand: Dezember 2015

München XXLInnenraum

Außenraum

Tarifzonen

Schnellbahnnetzmit Tram und ExpressBus

ExpressBus

Tram

Regional- / Fernzughalt

Mo-Sa tagsüber bis ca. 22 UhrSo&Feiertage kein Betrieb

AbschnittOstbahnhof - Ebersberg

v v

U8S6

Nur zeitweilig

Mammendorf

Malching

Maisach

Gernlinden

Esting

Olching

Gröbenzell

Lochhausen

Langwied PasingLaim Donnersberger-Hirsch-

garten brückeHacker-brücke

HauptbahnhofCentral Station

Karlsplatz(Stachus)

Marienplatz IsartorRosenheimerPlatz Ostbahnhof

Altomünster

Kleinberghofen

Erdweg

Arnbach

Markt Indersdorf

Niederroth

Schwabhausen

Bachern DachauStadt

Petershausen

Vierkirchen-Esterhofen

Röhrmoos

Heberts-hausen

Dachau

Karlsfeld

Allach

Untermenzing

Obermenzing

FreisingPulling

NeufahrnEchingLohhofUnter-schleißheim

Ober-schleißheim

Feldmoching

Fasanerie

Moosach

Flughafen MünchenMunich Airport

Flughafen Besucherpark

Hallbergmoos

Ismaning

Unterföhring

Johanneskirchen

Englschalking

Daglfing

Erding

Altenerding

Aufhausen

St. Koloman

Ottenhofen

Markt Schwaben

Poing

Grub

Heimstetten

Feldkirchen

Riem

Berg am Laim

Leuchtenberg-ring

Trudering

Gronsdorf

Haar

Vaterstetten

Baldham

Zorneding

Eglharting

Kirchseeon

GrafingBahnhof

GrafingStadt

Ebersberg

St.-Martin-Str.

Giesing

Perlach

Neubiberg

Ottobrunn

Hohenbrunn

Wächterhof

Höhenkirchen-Siegertsbrunn

Dürrnhaar

Aying

Peiß

Großhelfendorf

Kreuzstraße

Fasangarten

Fasanenpark

Unterhaching

Taufkirchen

Furth

Deisenhofen

Sauerlach

Otterfing

Holzkirchen

Heimeran-platz

Harras

Mittersendling

Siemenswerke

Solln

Großhesselohe Isartalbf.

Pullach

Höllriegelskreuth

Buchenhain

Baierbrunn

Hohenschäftlarn

Ebenhausen-Schäftlarn

Icking

Wolfratshausen

Westkreuz

Lochham

Gräfelfing

Planegg

Stockdorf

Gauting

StarnbergNord

Starnberg

Possen-hofen

Feldafing

Tutzing

Neuaubing

Harthaus

Freiham

Germering-Unterpfaffenhofen

Geisenbrunn

Gilching-Argelsried

Neugilching

Weßling

Steinebach

Seefeld-Hechendorf

Herrsching

Leienfelsstr.Aubing

Puchheim

Eichenau

Fürsten-feldbruck

Buchenau

Schön-geising

Grafrath

Türkenfeld

Geltendorf

Hasenbergl Dülferstr. Harthof Am Hart

MoosacherSt.-Martins-

PlatzOber-

wiesenfeldPetuel-ring

Georg-Brauchle-Ring

Gern

Rotkreuz-platz

Maillinger-str.

Stiglmaier-platz

FrankfurterRing

Milberts-hofen

PlatzBonner

Scheidplatz

Hohenzollernplatz

Josephsplatz

Theresienstr.

Königsplatz

Garching-ForschungszentrumGarching

Garching-Hochbrück

Fröttmaning

KieferngartenFreimann

Studentenstadt

Alte Heide

Nordfriedhof

Dietlindenstr.

MünchnerFreiheit

Giselastr.

Universität

Lehel

Max-Weber-Pl.

Richard-Strauss-Str.

Böhmerwaldplatz

Prinzregentenplatz

FriedenheimerStr.

Partnach-platzWestparkHolzapfel-

kreuthHaderner

Stern

Groß-hadern

Aidenbachstr.Machtlfinger

Str.

ForstenriederAllee

Basler Str.

Theresienwiese

Schwanthaler-höhe

Obersendling

Thalkirchen (Tierpark)

Brudermühlstr.

Implerstr. Poccistr. GoetheplatzFraunhoferstr.

Kolumbus-platz

Silberhorn-str.

Untersberg-str.

Candid-platz

Wettersteinplatz

St.-Quirin-Platz

Karl-Preis-Platz

Innsbrucker Ring

Michaelibad

Quiddestraße

Therese-Giehse-Allee

Kreillerstr.Josephs-

burg

Moos-feld

MessestadtWest

Olympia-Einkaufs-zentrum

Neuperlach Süd

Olympia-zentrum

Westfriedhof Arabellapark

Laimer PlatzWestend-

str.

KlinikumGroßhadern

FürstenriedWest

SendlingerTor

Mangfallplatz

Neuperlach Zentrum

MessestadtOst

Odeonsplatz

S2

S4

S7

S6

U2

U5

S8

U4

U4

U7

U3

U7U1

U5

U5

U1

S3

S4

S8

S20

U6

U6

S3

U3

S6

S7

U2

U8

S1

S2

U3

U2

20

12

16

1718

16 17

18 19

19 19

1525

27

28

18

16

21

135

Info

Index of participants

Aksu, Serhan Seyyare 99

Alauze, Xavier 32

Arrazola, Iñigo 35

Assémat, Frédéric 54

Baals, Christian 30

Barrett, Tom 22

Becher, Jan Hendrik 100

Bechler, Orel 24

Blaha, Martin 72

Borne, Adrien 101

Camacho, Arturo 102

Carey, Max 73

Cataldini, Federica 37

Cheng, Xiao-Hang 36

Chichet, Laure 46

Colquhoun, Craig 103

Colzi, Giacomo 104

Compagno, Enrico 74

Dabrowski, Michał 26

Davtyan, David 55

de Hond, Julius 105

De Rosi, Giulia 18

Dehabe, Michael 106

Dorier, Vincent 107

Eigen, Christoph 45

Elíasson, Ottó 42

136

Info

Elliott, Thomas 60

Enesa, Cédric 108

Engel, Felix 56

Faraoni, Giulia 75

Fischer, Christoph 109

Gabbrielli, Marco 64

Gebbe, Martina 76

Hannibal, Simon 77

Holland, Naomi 110

Holzmann, Daniela 48

Invernizzi, Andrea 65

Ireland, Philip 49

Jin, Shuwei 78

Jones, Ryan 66

Kaiser, Stefan 79

Kettmann, Peter 80

Klemt, Ralf 19

Knobloch, Christian 47

Kurlov, Denis 81

Kuyumjyan, Grigor 82

Lachman, Lukas 111

Lampis, Andreas 112

Lange, Karsten 70

Lebreuilly, José 113

Lefèvre, Grégoire 83

Legaie, Rémy 84

Lehtonen, Lauri 85

Livi, Lorenzo 68

137

Info

Lucivero, Vito Giovanni 69

Maiwoeger, Mira 114

Man, Jay 67

Mas, Hector 50

Meng, Yijian 33

Mihm, Moritz 115

Mohammed, Marwan 86

Mukhtar, Musawwadah 87

Niemietz, Dominik 88

Ołdziejewski, Rafał 31

Panigrahi, Jayash 89

Parniak, Michał 25

Paul, Daryl 116

Pecak, Daniel 20

Perrier, Maxime 90

Petter, Daniel 91

Pigneur, Marine 43

Pokorny, Fabian 57

Pruefer, Maximilian 44

Ramakrishna, Kushal 117

Reyes, Ignacio 118

Rubio Abadal, Antonio 92

Sandholzer, Kilian 93

Sbroscia, Matteo 119

Schnell, Alexander 38

Sengottuvel, Saravanan 34

Skalmstang, Kristoffer Theis 120

Sobirey, Lennart 94

138

Info

Sturm, Martin 58

Varguet, Hugo 121

Venegas-Gomez, Araceli 95

Ville, Jean-Loup 59

White, Andrew 122

Will, Elisa 23

Wolf, Philip 123

Yago, Jorge 21

Zamora-Zamora, Roberto 96

Zimmer, Christian 97

139

Info

Organisation committee

[email protected], from left to right:

Thomas GantnerAlexander PrehnMartin IbrüggerBastian HackerStephan WelteMatthias KörberSteffen Schmidt

Scientific committeeEva-Katharina Dietsche Collège de France, ParisPau Farrera ICFO, BarcelonaMoritz Hambach Imperial College, LondonStephan Helmrich University of HeidelbergSebastian Hild MPQ, GarchingSven Krönke University of HamburgJulian Léonard ETH ZurichFrieder Lindenfelser ETH ZurichVanessa Paulisch MPQ, GarchingElisa Will TU Vienna

140

Info

About YAO

Since 1995 the YAO conference is held annually in different institutes all overEurope and is organized by local PhD students. With the conference, its mascottravels through the scientific world.

Previous and future host cities:

1995: Innsbruck, Austria 2007: Durham, United Kingdom

1996: Oxford, United Kingdom 2008: Florence, Italy

1997: Parco dell’Orecchiella, Italy 2009: Vienna, Austria

1998: Gif-sur-Yvette, France 2010: Amsterdam, Netherlands

1999: Potsdam, Germany 2011: Hannover, Germany

2000: Brighton, United Kingdom 2012: Krakow, Poland

2001: Stuttgart, Germany 2013: Birmingham, United Kingdom

2002: Volterra, Italy 2014: Barcelona, Spain

2003: Amsterdam, Netherlands 2015: Zurich, Switzerland

2004: Innsbruck, Austria 2016: Munich, Germany

2005: Hannover, Germany 2017: Paris, France

2006: Palaiseau, France 2018: ?

141

Info

SponsorsWe gratefully acknowledge institutional support ...

... as well as our industrial partners:

142

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NEW

AZ_DIN-A5_Yao_2016.indd 1 09.12.2015 16:43:55

www.yao-conference.org

Munich and Garching, Germany

Max Planck Institute of Quantum Opticsand

TUM Institute for Advanced Study

22nd young atom opticians conference 2016 · young atom opticians conference 22 nd young atom...

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