METROLOGY FOR QUANTUM COMMUNICATION

Transcription

1 METROLOGY FOR QUANTUM COMMUNICATION Giorgio Brida Workshop on Fiber Optics Metrology needs 19 September 2016 Paris, BIPM

2 Metrology for Industrial Quantum Communications Sept Aug. 2014

3 Metrology for Industrial Quantum Communications Project Partners

4 This project follows on from EMRP project MIQC Optical metrologyfor quantum-enhancedsecuretelecommunication July2015 June2018

5 Optical metrology for quantum-enhanced secure telecommunication Project Partners

6 Metrology for Industrial Quantum Communications Objective : to develop a pan-european measurement infrastructure to develop standards and characterisation facilities for commercial Quantum Key Distribution(QKD) devices. QKD devices require independent physical characterisation in order to convince end-users that the technology is working within specification Focus on faint-pulse (weak coherent pulse) QKD overfibreat1550nm

7 Standardisation These projects work closely with the ETSI Industry Specification Group on QKD ETSI ISG-QKD

8 Metrology for Industrial Quantum Communications Focus on faint-pulse(weak coherent pulse) QKD over fibre at 1550 nm Photon emitters Traceable characterisation of commercial QKD sources: Attenuated laser pulses Quantum channel (optical fibre) and RNG Traceable characterisation of single mode optical fibre Characterisation of propagation of photon state in single mode fibre Open system true physical quantum random number generator (QRNG) QRNG physically characterised and tested under different operating conditions Photon receivers Traceable calibration of commercial QKD receivers: Gated photon counting detectors June 2014

9 Key Measurement Outputs of MIQC Focus on faint-pulse(weak coherent pulse) QKD over fibre at 1550 nm Photon emitters Traceable characterisation of commercial QKD sources: Attenuated laser pulses Quantum channel (optical fibre) and RNG Traceable characterisation of single mode optical fibre Characterisation of propagation of photon state in single mode fibre Open system true physical quantum random number generator (QRNG) QRNG physically characterised and tested under different operating conditions Photon receivers Traceable calibration of commercial QKD receivers: Gated photon counting detectors June 2014

10 Receiver s Detectors Detectors parameters considered [1/2] Parameter Symbol Units Definition Measurement approach Photon detection probability h probability/ gate The probability that a photon incident at the optical input will be detected within a detection gate. Via a calibrated laser light source and a calibrated filter Dark count probability P dark (probability /gate) The probability that a detector registers a detection event per gate, despite the absence of optical illumination. As above (1) Afterpulse probability P afterpulse (probability /gate) The probability that a detector registers a false detection event in the absence of illumination, conditional on a true photon detection event in the preceding detection gate. Dead time T dead ns/µs The smallest time duration after which the detection efficiency is independent of previous photon detection history. Recovery Time T rec ns/µs The time duration after a photon detection event for the detection efficiency to return to 99% of its steady-state value. This is only important if the detector is passively quenched June 2014 As above (1) Via a train of two optical pulses with tuneable temporal separation As above(4)

11 Detectors parameters considered [2/2] Parameter Symbol Units Definition Measurement approach Maximum count rate C max Receiver s Detectors MHz/GHz The maximum rate of photon detection events under strong illumination condition in the single/few photon/gate regime. Timing jitter T jitter ps/ns The uncertainty in determining the arrival time of a photon at the optical input. This will be determined by the photon detection efficiency, the dead time, and dark counts Measure the FWHM in the distribution of detection times Maximum clock frequency F max MHz/GHz The maximum clock frequency at or below which a detector can be operated in a QKD system without giving rise to an intolerable bit error rate. Spectral Responsivity R s unitless The photon detection efficiency as a function of wavelength of the incident photons. Via a calibrated laser light source with known wavelength (wavemeter) and a calibrated filter June 2014

12 Detectors parameters considered [1/2] (again!) Parameter Symbol Units Definition Measurement approach Photon detection probability h probability/ gate The probability that a photon incident at the optical input will be detected within a detection gate. Via a calibrated laser light source and a calibrated filter Dark count probability P dark (probability /gate) The probability that a detector registers a detection event per gate, despite the absence of optical illumination. As above (1) Afterpulse probability P afterpulse (probability /gate) The probability that a detector registers a false detection event in the absence of illumination, conditional on a true photon detection event in the preceding detection gate. Dead time T dead ns/µs The smallest time duration after which the detection efficiency is independent of previous photon detection history. Recovery Time T rec ns/µs The time duration after a photon detection event for the detection efficiency to return to 99% of its steady-state value. This is only important if the detector is passively quenched June 2014 As above (1) Via a train of two optical pulses with tuneable temporal separation As above(4)

13 Optical power traceability chain (SI) % uncertainty Primary standard Cryogenic radiometry NMI reference detectors visible wavelengths, 0.5 mw, collimated, free-space laser radiation Low power reference detector 1 % uncertainty (k = 2) 1550 nm, 100 pw, output from optical fibre June 2014

14 Optical power traceability chain (SI) 200 µw Φ= N (hc/λ) ECSR Air coupling, 2mm beam Uncertainty 100 ppm 100 db TRACEABILITY - Stability - Beamshape - Background -!!! TES SPAD Air/fibre coupling, 10 μm beam Uncertainty?? SSPD N 532 nm -2,74 db 633 nm -1,99 db 850 nm -0,71 db 1550 nm +1,90 db

15 PTB Cryogenic Radiometer Novel reference for calibrating single-photon detectors based on synchrotron radiation PTB reference InGaAs detector MetrologyLight Source dedicated electron storage ofptb Superconducting Single Photon Detector N e 9 10 N e 3 10 Exploitation of strict proportionality of ring current and emitted radiation Number of stored electrons changes spectral radiant power over 11 orders of magnitude without changes to the emitted spectrum * QE SSPD = count rate SSPD number of stored electrons (I low ) photon rate Trap number of stored electrons (I high ) June 2014

16 Key Measurement Outputs of MIQC Photon emitters Traceable characterisation of commercial QKD sources: Attenuated laser pulses Quantum channel (optical fibre) and RNG Traceable characterisation of single mode optical fibre Characterisation of propagation of photon state in single mode fibre Open system true physical quantum random number generator (QRNG) QRNG physically characterised and tested under different operating conditions Photon receivers Traceable calibration of commercial QKD receivers: Gated photon counting detectors June 2014

17 Key Measurement Outputs of MIQC Focus on faint-pulse(weak coherent pulse) QKD over fibre at 1550 nm Photon emitters Traceable characterisation of commercial QKD sources: Attenuated laser pulses Quantum channel (optical fibre) and RNG Traceable characterisation of single mode optical fibre Characterisation of propagation of photon state in single mode fibre Open system true physical quantum random number generator (QRNG) QRNG physically characterised and tested under different operating conditions Photon receivers Traceable calibration of commercial QKD receivers: Gated photon counting detectors

18 Emitter s Sources Source parameters considered [1/2] Parameter Symbol Units Definition Measurement approach Frequency (Rep. Rate) F Hz The frequency set by the pulse generator Measure via standard traceable frequency calibration techniques Mean photon number µ Photons /pulse a) calibrated detector and commercial attenuator Average number of photons per pulse emitted by Alice b) calibrated detector and traceable attenuator based on InGaAs photodiodes c) reconstruction of probability distribution d) Photon number resolving detector based on commercial single photon detector in tree configuration Mean photon number variation Source timing jitter J S σ µ psorns The uncertainty in the emission time of a photon at the optical output. As above Measure FWHM of distribution of photon emission times with respect to pulse generator signal June 2014

19 Source parameters considered [2/2] Parameter Symbol Units Definition Measurement approach Source wavelength λ nm Wavelength of photons that are emitted. Spectral line width δ GHz Bandwidth of the emitted photons. Spectral indistinguishability Temporal indistinguishability Polarisation state s ind t ind Emitter s Sources Unitless The extent to which the encoded states can be distinguished through spectral measurement. Unitless The extent to which the encoded states can be distinguished through temporal measurement. Wavemeter Beat note measurement or Fabry-Perot interferometer. Fabry-Perot interferometer: compare spectra of different encoding states The probability distribution with respect to time for laser output pulses is measured. tind is calculated according to reference [12]. Polarisation reconstruction June 2014

20 Source parameters considered [1/2] (again!) Parameter Symbol Units Definition Measurement approach Frequency (Rep. Rate) F Hz The frequency set by the pulse generator Measure via standard traceable frequency calibration techniques Mean photon number µ Photons /pulse a) calibrated detector and commercial attenuator Average number of photons per pulse emitted by Alice b) calibrated detector and traceable attenuator based on InGaAs photodiodes c) reconstruction of probability distribution d) Photon number resolving detector based on commercial single photon detector in tree configuration Mean photon number variation Source timing jitter J S σ µ psorns The uncertainty in the emission time of a photon at the optical output. As above Measure FWHM of distribution of photon emission times with respect to pulse generator signal June 204

21 Source photon number statistics Reconstruction of probability distribution ON/OFF Tomography Photon number distribution For on/off detectors like SPAD with quantum efficiency, the probability of noclicks is: -Truncating the p.d. to a certain -Changing the value of the quantum efficiency Poissonian Reconstructed June 2014

22 Source photon number statistics Transition Edge Sensor i.e. µcalorimeter working at superconductive phase transition 1310 nm laser

23 Source photon number statistics d) PNR detector based on tree configuration Deconvolving the p.d. of incoming photons BS BS BS Detector Tree: 4 click/no-click detectors Novel (entanglemet-assisted) quantum characterisation technique for PNR detector Brida et al., PRL 108, (2012) By measuring higher-order g (n), it is possible to deconvolve the underlying number and kind (poissonian, pseudotermal or single-photon) of occupied modes of a light field. (2) (3) (4) ( n) P ( n) g, g, g g = n Goldschmidt et al., PRA P ( 1) 88, (2013) June 2014

24 Source parameters considered [2/2] (again!) Parameter Symbol Units Definition Measurement approach Source wavelength λ nm Wavelength of photons that are emitted. Wavemeter Spectral line width δ GHz Bandwidth of the emitted photons. Spectral indistinguishability Temporal indistinguishability Polarisation state s ind t ind Unitless The extent to which the encoded states can be distinguished through spectral measurement. Unitless The extent to which the encoded states can be distinguished through temporal measurement. Beat note measurement or Fabry-Perot interferometer. Fabry-Perot interferometer: compare spectra of different encoding states The probability distribution with respect to time for laser output pulses is measured. Polarisation reconstruction

25 Source Spectrum Wavelength Optical pulses of duration < 100 ps Spectral width: ν source ~ 12 GHz (@1550 nm) Target uncertainty in λ source of δλ source < 0.01 nm (1.2 nm) Wavemeter measurement Needs to be high flux (before attenuation) standard interferometer design not necessarily good for pulsed laser can use alternative design (eg High Finesse) suitable for pulsed sources June 2014

26 Source Spectrum Tunable single-photon spectrometer Operating range nm FSR = 119 GHz, ν cavity = 600 MHz Low drift rate & single-photon sensitivity Tune to resonance and scan across QKD source spectrum Can be used to analyse different source encoding spectra Technically challenging to improve spectral resolution June 2014

27 Source parameters considered [2/2] (again!) Parameter Symbol Units Definition Measurement approach Source wavelength λ nm Wavelength of photons that are emitted. Wavemeter Spectral line width δ GHz Bandwidth of the emitted photons. Spectral indistinguishability Temporal indistinguishability Polarisation state s ind t ind Unitless The extent to which the encoded states can be distinguished through spectral measurement. Unitless The extent to which the encoded states can be distinguished through temporal measurement. Beat note measurement or Fabry-Perot interferometer. Fabry-Perot interferometer: compare spectra of different encoding states The probability distribution with respect to time for laser output pulses is measured. Polarisation reconstruction June 2014

28 Noiseless Heralded SPS HBT g (2) = t switch = 2ns Bridaet al., APL 101, (2012) June 2014 t switch

29 Key Measurement Outputs of MIQC Photon emitters Traceable characterisation of commercial QKD sources: Attenuated laser pulses Quantum channel (optical fibre) and RNG Traceable characterisation of single mode optical fibre Characterisation of propagation of photon state in single mode fibre Open system true physical quantum random number generator (QRNG) QRNG physically characterised and tested under different operating conditions Photon receivers Traceable calibration of commercial QKD receivers: Gated photon counting detectors June 2014

30 Key Measurement Outputs of MIQC Phase encoded, attenuated laser pulse QKD over fibre at 1550 nm Photon emitters Traceable characterisation of commercial QKD sources: Attenuated laser pulses Quantum channel (optical fibre) and RNG Traceable characterisation of single mode optical fibre Characterisation of propagation of photon state in single mode fibre Open system true physical quantum random number generator (QRNG) QRNG physically characterised and tested under different operating conditions Photon receivers Traceable calibration of commercial QKD receivers: Gated photon counting detectors June 2014

31 Polarization state reconstruction - CW or quasi-cw source before attenuation: conventional polarimeter - Pulsed source (challenging) - Attenuated Source (single-photon light level): quantum state tomography - Issue: polarization stability Evaluation of the parameters: {S1, S2, S3} 3 projective measurements: : June 2014

32 MIQC 2

33 MIQC 2 WP1: Counter-measures and novel optical components for commercial fibre-based QKD The aim of this work package is to characteriseand validate counter-measures to side-channel and Trojan-horse attacks in order to ensure the security of fibre-based QKD systems. This activity is carried on in strict collaboration with the ETSI Industry Specification Group on QKD. Identify vulnerabilities of passive and active components Develop and verify counter-measures Develop security models Characterise a new, high-speed, type of SPAD Intercomparison of fibre-coupled DE and g2

34 MIQC 2 WP2: Metrology for commercial components for free-space QKD The aim of this work package is to establish measurement and characterisationfacilities for components of free-space QKD devices. Within the scope of this project, we define the spectral range as that where silicon-based detectors are applicable, i.e. between 400 nm and 950 nm. Develop characterisationfacilities facilitiesfor free-space QKD components develop tests for Quantum Random Generators absolute reference detector for in-situ calibration of SPADs Intercomparisonof free-space DE and g2

35 MIQC 2 WP3: Metrology for next generation (entanglementbased) QKD The aim of this work package is to foster the development of a measurement infrastructure for entanglement-based (next-generation) QKD systems, such as device-independent, measurement device-independent and reference-frame independent QKD. Develop metrics and measurement apparatus for entanglement and quantumness quantification Apply to key properties of measurementdevice-indipendentqkd

36 MIQC 2 IMPACT Joint Virtual European Metrology Centre for Quantum Photonics a general objective of the project is investigating the possibility of establishing the Joint Virtual European Metrology Centre for Quantum Photonics between the partners. A strategic analysis for the creation of this Centre will be carried out, which will include consultation with stakeholders and CCPR, and report on the need and proposed terms-ofreference for this Joint Centre.

37 MIQC 2 Achievements SPAD back-flash emission pilot comparison of SPAD d.e. entanglement meas. for QKD applications Fiber link 640 km QKD INRIM-LENS (Florence) done started on going on going

38 Photon-counting optical time-domain reflectometry at 1550 nm Back-flash from SPAD

39 Pulse generator Pulsed laser ID300 Optical attenuator circulator sync Correlator Free running SPAD ID220 Fibre optic device Workshop on Fiber Optics Metrology NEWRAD 2014, needs June, September Espoo 2016 Paris, BIPM

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41 Counts Round & trip SPAD dead time 1 km fibre Rate 10 khz α = 33 db T = 1 h bin = 1,024 ns t/µs

42 Pulse generator Pulsed laser ID300 Optical attenuator circulator sync Correlator Free running SPAD ID220 SPAD Workshop on Fiber Optics Metrology NEWRAD 2014, needs June, September Espoo 2016 Paris, BIPM

43 SPAD - OFF 1000 Counts t/ns t/ns

44 SPAD - ON 1000 Counts t/ns t/ns

45 SPAD - OFF 1000 Counts t/ns t/ns

46 10 4 SPAD - ON 1000 Counts t/ns t/ns

47 SPAD - ON Increasing the excess bias voltage Workshop on Fiber Optics Metrology NEWRAD 2014, needs June, September Espoo 2016 Paris, BIPM

48 I-QB POINT-TO-POINT LINK

49 First phase: december 2015 INRIM SANTHIA Link: INRIM SANTHIA 92 Km, -27 db losses Clavis 3 system(emitter& Receiver) 2xID230 externaldetectors : SKR >10 30 db 2 PC or Laptop to control Clavis3 units

50 Alice PC/Laptop Ethernet (WAN) 19 rack 19 rack FC/PC ID230 SMA Bob ID230 Ethernet (LAN) Classical channel FC/PC SMA Clavis 3 ITU nm ITU nm 2x LC/PC ITU nm FC/APC WDM ADD DROP ITU29 ITU30 AMPLIF. + FILTER ADD DROP WDM Clavis 3 2x LC/PC FC/APC ITU30 ITU29 FC/APC SMA FC/APC SMA Power consumptionof the Clavis 3 : <250W (220AC) Quantum channel (dark fiber) PC/Laptop Ethernet (WAN) Ethernet (LAN)

51 I-QB: 1st Meeting: October 14th, 2015 Second phase: december Optimisation of first phase link SKR >10 30 db Link: INRIM UNIFI-LENS 642 km, -171 db losses Sub-link losses: -25 to -34 db 7 TN and 6 sub-links Detectors at 4 nodes TNs architecture to transmit securely the secret key over long distances

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