Economic Stimulus: Valorization of Single Photon Detectors and Quantum Key

Distribution Systems

Hugo Zbinden

Group of Applied Physics (GAP), UNIGE

NCCR Transfert Projects (GAP – id Quantique):High Speed Single Photon Counting Module (H.Z.)

Second Generation QKD Engine (N. Gisin)

ID Quantique

Encryption Business Unit InstrumentationBusiness Unit

• Spin-off from GAP based in Geneva• Founded in 2001• 17 employees ( 4 from GAP)• Customer base on 6 continents

Technology

- Single-photon detectors

Two product lines- High-Speed Encryption- Quantum Cryptography RNG Business Unit

Services(training, installation, maintenance)

3 business units

NCCR-QP Project 4:Single Photon Detectors

1. InGaAs Avalanche photon detectors2. Supraconducting Detectors3. Hybrid schemes: Upconversion detectors, photon number resolving etc

Performance:

= 10-20%

Pdark = 1000/s

Timing jitter = 300 ps

Max. Rate = 100 kHz

Si-APD:

50 %

cdark = 10/s

50 ps

10 MHz

InGaAs Avalanche Photo Diode

U

IU B ias

Afterpulsing is a problem

Mitigation: - deadtime- rapid quenching or short gates

-> limited count rate, duty cycle < 1

t

U B ias

U B reak do w n

Sinus gating allows high count rates

Pulse rate 1.25 GHz, gate width ~130ps (FWHM)

Novel APD with negative feedback for free running

operationInternal resistor quenches rapidly

the avalancheSlow recharging-> nice results in free running

mode:poster of Tommaso Lunghi

Versatile detector moduleSpecifications: Gated mode up to 100 MHz Variable gate length 1ns to 10ns Free running

Integrated counters, clock, variable delay etc Inputs and outputs in NIM, ECL, TTL etc «cool» user interface Easy upgradable with new functions (TDC,

histogram)

id 210 as a whole

People: Jun Zhang (physicist), APD characterisation, measurements

Claudio Barreiro (engineer), pulser electronicsOliver Guinnard (engineer), design, electronics, mechanicsBernard Clausen (engineer), electronicsAlexis Rochas (physicist), concept and testingJean-Benoit Page (engineer), programming, user interfaceLaurent Monat (engineer), electronics and FPGATony Matteo (engineer), production

The Result:

Quantum Key Distribution

Quantum Cryptography is not a new coding method, it allows to create a secret key

Security is based on the laws of quantum physics “A measurement perturbs the system in an irreversible way”. A spy listening to the “quantum communication”, disturbs the system and will be detected.

The basic idea is simple

Alice EveBob

Error with 25 % probabilityÞ The error rate (QBER) indicates the

presence of Eve and the information she possesses(in practice typical QBER ~1-2%)

1

01

00

Key DistillationAlice Bob

Quantum channel

Public channel

(losses)

Qubits

TransmissionBasis

Reconciliation

QBERestimate

Error

correctionPrivacy

amplification

Sifted key

Raw key

Key Key

Smolin and BennettIBM 1989

id Quantique 20062 (dark) fibersDistance 100km

100 MHz EthernetNot One Time Pad!

The plug & play system is getting old

Faint laser BB 84, two way scheme5 MHz pulse rate1 kbit/s secret bit rate @ 25km

presented at CeBit 02 with guest star Sandra Pochon!

- Coherent faint laser pulses (µ~0.5)- 150 km of installed and standard fibres, 43dB of losses- SECOQC 2008 (Vienna)

Coherent-One-Way (COW) scheme

tB D B

D M 1D M 2

1 t BL ase r IM

b it 0b it 1 d ec o y

Industrial COW prototype: 1000 times higher bit rates

625 MHz rate (1.25 GHz pulse rate) 1 Mbit/s secret key rate @ 25km

WDM of quantum and classical channel real time distillation (FPGA) security, finite key analysis

The QCrypt Concept

100 Gb/s

1 Mb/s OTP

High-speed Quantum Key Distribution +

40 – 100Gbps enCRYPTion +

WDM

QKD Engine Results:

250 ps

Tfwhm=138 ps

500 600 700 800 900 10000.00

0.02

0.04

0.06

0.08

0.10

0.12

T=129 ps

Gate frequency: 1.25 GHz

Det

ectio

n ef

ficie

ncy

Delay [ps]

Intensity modulation Sinus gating detector

Short gatesLow afterpulsingHigh count rates

QKD and WDM Goal: Key distribution and high speed data

encryption over a single optical fibre Commercial QKD (plug & play)

and AES-encryptors (256 bits keys, 1 Gbps rate)

New Journal of Physics 12 (2010) 063027

Classical communication channel

Dedicated quantum channel

AliceBob AliceBob

Experimental Results

Fiber attenuation: -0.207 dB/kmDetection efficiency: 0.07Dark count rate: 510-6 ns-1

Dead time: 10 sDWDM isolation: 82 dB

Thank you for y

our

attentio

n