multiphoton dressing of an anharmonic superconducting many ... · neeley nat. phys. 4 (2008)...
TRANSCRIPT
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Multiphoton dressing of an anharmonic
superconducting many-level quantum circuit
Martin P. Weides
Johannes Gutenberg University Mainz, Germany
and Karlsruhe Institute of Technology (KIT), Germany
June 4th 2015
Quantum Metamaterials Workshop QMM Spetses
J. Braumüller, J. Cramer, S. Schlör, H. Rotzinger, L. Radtke, A. Lukashenko, P. Yang,
S. T. Skacel, S. Probst, M. Marthaler, L. Guo, A. V. Ustinov
Resonator
Qubit
fast-flux bias
300 µm
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Martin Weides, QMM Spetses 2015 2
� Introduction
� Anharmonic many-level quantum circuit
� Power spectroscopy
� Dispersive resonator shift
� Rabi sideband transition of multi-photon coupled levels
� QMM � scale up! Concentric transmon qubits
� 2d qubits with 10us coherence
� Prospect
� QuantumMagnonics: qubits & spinwaves
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Martin Weides, QMM Spetses 2015 3
Capacitively shunted Josephson Junction
� Anharmonic oscillator
Non-linear LC oscillator
Magnetic flux Φ changes LJ(φ)
Φ
Transmon qubit
Two lowest levels � Bloch sphere
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Martin Weides, QMM Spetses 2015 4
Quantum lab
� Sputter tool (Al, Nb, NbN)
� Tunnel junction shadow evaporation (Al-AlOx-Al)
� Lithography and etching
� Large volume He3/He4 dilution refrigerator
�RF (18) and DC (24) wires, filters, amplifiers
�9 samples (6 qubits, 3 resonators)
� Time-domain setups (2), microwave spectroscopy
� Software (simulation, measurement)
200 nm
10 µm
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Martin Weides, QMM Spetses 2015 5
� Introduction
� Anharmonic many-level quantum circuit
� Power spectroscopy
� Dispersive resonator shift
� Rabi sideband transition of multi-photon coupled levels
� QMM � scale up! Concentric transmon qubits
� 2d qubits with 10us coherence
� Prospect
� QuantumMagnonics: qubits & spinwaves
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Martin Weides, QMM Spetses 2015 6
Anharmonic many-level quantum circuit
consideration of higher quantum levels:
transmon qubit:
weak anharmonicity
Neeley Nat. Phys. 4 (2008)
Fedorov Nat. 481 (2011)Bruß PRL 88 (2002)
Cerf PRL 88 (2002)
Paraoanu JLTP 175 (2014)
enhanced security of key
distribution in quantum
cryptography
quantum
simulation
efficient & robust
quantum gates, qudit
JB et al., PRB 91 (2015)
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Martin Weides, QMM Spetses 2015 7
Experiment
� microstrip geometry
� overlap Josephson junction
� transmon regime: �� ≫ �� ⇒ ��~0.05
� spectroscopic measurements
� VNA readout tone
� microwave drive/probe tone
TL
Blais PRA 69 (2004)
Koch PRA 76 (2007)
Sandberg APL 102 (2013)
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Martin Weides, QMM Spetses 2015 8
Qubit spectroscopy40cm
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Martin Weides, QMM Spetses 2015 9
Power spectroscopy – multiphoton transitions
� five bound states in Josephson potential
� dispersive shift scales with excitation
number ‹n›
Braumüller et al., PRB 2015
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Martin Weides, QMM Spetses 2015 10
Dispersive shift of higher levels
� Rotating-wave Hamiltonian
� g01 = 115 MHz, ∆≈1 GHz
Braumüller et al., PRB 2015
Qubit shift Resonator shift by qubit levels
|S21(ω
)|2
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Martin Weides, QMM Spetses 2015 11
Power spectroscopy – simulation
measurement
simulation
Braumüller et al., PRB 2015
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Martin Weides, QMM Spetses 2015 12
Multiphoton dressing � − � , Rabi sidebands
� 0 , 2 degenerate in rotating
frame � dressing
� Probing of level structure (in
rotating frame) with weak
probe tone
measurement simulation
Braumüller et al., PRB 2015
Sweep drive power Pdµω
& probe frequency ωpµω
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Martin Weides, QMM Spetses 2015 13
Multiphoton dressing – pumping the |�⟩-level
Dynamical coupling of levels by probe tone
� Autler-Townes like avoided crossing
measurement
simulation
Braumüller et al., PRB 2015
Sweep drive ωdµω
& probe ωpµω
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Martin Weides, QMM Spetses 2015 14
Multiphoton dressing – pumping the |�⟩-level
measurement
simulation
Braumüller et al., PRB 2015
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Martin Weides, QMM Spetses 2015 15
� Introduction
� Anharmonic many-level quantum circuit
� Power spectroscopy
� Dispersive resonator shift
� Rabi sideband transition of multi-photon coupled levels
� QMM � scale up! Concentric transmon qubits
� 2d qubits with 10us coherence
� Prospect
� QuantumMagnonics: qubits & spinwaves
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Martin Weides, QMM Spetses 2015 16
Adding complexity12 qubits on-chip with local detuning
150 µm
Resonator
Flux bias I
Qubit
Transmission line
MA thesis J. Cramer (2015)
Φ
Coherence
T1=0.53 µs; T2 = 0.4 µs
5 mm
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Martin Weides, QMM Spetses 2015 17
Novel design: Tunable concentric transmons
Devoret, Schoelkopf Science (2013)
� Long coherence: scalable quantum computation, error correction
� High experimental flexibility by fast flux tuning
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Martin Weides, QMM Spetses 2015 18
Novel design: Tunable concentric transmon qubit (2d)
Coherence �� limited by energy relaxation ��
� Minimize surface/interface loss (TLS) � microstrip design
� Reduce radiative decay , i.e. qubit‘s dipole moment
� All Al-AlOx-Al technology
� Qubit: electron-beam
� All other: optical, lift-off
� Fast (ns) tunability
� Side-selective
inductive ���-coupling
Resonator
Qubit
fast-flux bias
300 µm
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Martin Weides, QMM Spetses 2015 19
Concentric transmon qubit – low power spectroscopy
���/2�
1
2���/2�
excitation tone
dis
pe
rsiv
e r
eso
na
tor
shif
t
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Martin Weides, QMM Spetses 2015 20
Concentric transmon qubit – high power spectroscopy
���/2�
1
2���/2�
exc
ita
tio
n t
on
e
dis
pe
rsiv
e r
eso
na
tor
shif
t
1
3���/2�
1
4���/2�
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Martin Weides, QMM Spetses 2015 21
Concentric transmon qubit – flux spectroscopy
�� = 116MHz, �� = 69GHz, ��, = 138nA
�� ��⁄ = 595
Φ
~ Idc
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Martin Weides, QMM Spetses 2015 22
Pulsed (time-domain) measurements
Pulsed dispersive qubit readout
� resonator only driven during readout
to avoid state collapse (quantum
measurement)
Time-resolved qubit manipulation
� heterodyne single-sideband mixing
� quantum state tomography
to sample from sample
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Martin Weides, QMM Spetses 2015 23
Pulsed measurements – Rabi oscillations
arg
�11
(a
.u.) |0〉
|1〉
� (��)
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Martin Weides, QMM Spetses 2015 24
Pulsed measurements – Coherence
P1
P0
0 10 20 30
t [µs]
T1=9.1 µs
P1
P0
0 10 20 30
t [µs]
echo T2=10.2 µs
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Martin Weides, QMM Spetses 2015 25
Pulsed measurements – fast z (energy splitting)-control
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Martin Weides, QMM Spetses 2015 26
Pulsed measurements – Tomography, small detuning
decay from
1 2⁄ �|0〉 � |1〉� (x-axis)
� Long coherence qubits
�Measurement techniques (spectroscopic, pulsed)
�Quantum Simulation (Spin-Bose)
�Quantum Metamaterials (N Qubits- 1 Resonator)
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Martin Weides, QMM Spetses 2015 27
� Introduction
� Anharmonic many-level quantum circuit
� Power spectroscopy
� Dispersive resonator shift
� Rabi sideband transition of multi-photon coupled levels
� QMM � scale up! Concentric transmon qubits
� 2d qubits with 10us coherence
� Prospect
� QuantumMagnonics: qubits & spinwaves
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Martin Weides, QMM Spetses 2015 28
Magnon: quantized spin wave excitation
Future information technology
(e.g. spin-torque oscillator, spin-wave propagation control for logic)
Strong magnon damping: magnon/phonon/electron scattering
Grand challenge:
To understand physics, single magnon information needed!
Slavin et al., Nat. Nanotech. ´09 Vogt et al., Nat. Commun. ´14
Attenuation length ~10 umLinewidth Δf > 1 MHz
Magnonics: spin waves in nanostructures
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Martin Weides, QMM Spetses 2015 29
‘Classical measurement’:
� Inelastic scattering (neutron, photon, electron)
� Ferromagnetic resonance
Drawbacks:
� Weakly (not coherent) coupled
� Large flux, small signal (statistics)
� Thermally excited population (T > 4 K)
Difficult to access magnon ground state!
Status quo
magnonscattered
incident
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Martin Weides, QMM Spetses 2015 30
� Quantum ground state (T=10 mK)
� Ultra-low power spectroscopy, coherent coupling
� How to achieve?
Extend magnon to artificial spin!
Access magnon lifetime and coherence via coherent coupling
How to probe a single magnon?
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Martin Weides, QMM Spetses 2015 31
Strong coupling:
� Qubit < 1 MHz
� Magnon Ni80
Fe20
< 50 MHz, Y3Fe
5O12
< 5 MHz
Coupling rate g (N number of spins in qubit mode volume V0)
> 100 MHz (strong coupling)
Coherent coupling requirement
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Martin Weides, QMM Spetses 2015 32
KIT-Team
BA
Cem Kücük
Marcel Langer
Tomislav Piskor
Alexander Stehli
Patricia Stehle
MA
Joel Cramer
Lukas Grünhaupt
Marco Pfirrmann
Steffen Schlör
Andre Schneider
PhD
Jochen Braumüller
Saskia Meißner
Sebastian Probst
Ping Yang
Technician
Lucas Radtke
Scientists
Michael Marthaler
Hannes Rotzinger
Sasha Lukashenko
Alexey Ustinov
NIST
Farnaz Farhoodi
Jeffrey Kline
Martin Sandberg
Michael Vissers
David Pappas
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Martin Weides, QMM Spetses 2015 33
Thank you for your attention