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Detectors of single photons (…on the road to nano)

Detectors of single photons (…on the road to nano). O. Haderka. Regional Center for Advanced Technologies and Materials, Joint Laboratory of Optics, Palacký University, 17. listopadu 50a, 772 07 Olomouc, Czech Republic. Why to detect single photons?.

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Detectors of single photons (…on the road to nano)

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  1. Detectors of single photons (…on the road to nano) O. Haderka Regional Center for Advanced Technologies and Materials, Joint Laboratory of Optics, Palacký University, 17. listopadu 50a, 772 07 Olomouc, Czech Republic.

  2. Why to detect single photons? • In classical optics – every photon is valuable (e.g., in astronomy) • In quantum optics/information • time-correlated photon counting (TCPC) • some tasks benefit from single photons (QKD, QM) • other tasks require single photons (LOQC) • Other applications in particle physics, biomedical research, atmospheric pollution measurements, LIDAR etc.

  3. internal coupling coupling optics detector amplifier/integrator sampling/ADC gain losses ηconv ηcollect γint γext ηentry x n m Photon detection event • Coupling • Conversion of optical quanta to another medium (usually electron or electron-hole pair) • Amplification to macroscopic level • Sampling/Thresholding

  4. General characteristics • Spectral properties • conversion quantum efficiency ηconv • Timing properties • dead time • jitter • Noise properties • dark count rate d • probability of afterpulses • Ability to resolve number of photons • excess noise • pulse-height diagram • single-shot vs. statistics

  5. Overview of current technologies • Photomultiplier tubes • Avalanche photodiodes • Hybrid photodetectors • Visible light photon counters • Transition-edge sensors • Frequency up-conversion • Superconducting nanowires • Quantum dots & defects • Carbon nanotubes (?)

  6. HamamatsuBurle Photomultiplier tubes • the oldest photon-counting detector (1949) • large active areas ( > 10 mm) • amplification excess noise can be lowered using first dynode from suitable material (GaP) • η = 40% @ 500 nm (GaAsP)d ≈ 100 Hz, Δt ≈ 300 ps • η = 2% @ 1550 nm (InP/InGaAs @ 200 K), d ≈ 200 kHz

  7. Perkin-Elmer Micro Photon Devices idQuantique Single-photon avalanche photodiode (SPAD) • photodiode reverse biased above breakdown (Geiger mode) • avalanche stopped by quenching circuit • Si: η = 70% @ 650 nm, d ≈ 25 Hz,Δt ≈ 400 ps,τ = 50 ns, high excess noise • back-flashing • d can be lowered to 8x10-4 Hz by cooling to 78K • shallow-junction: Δt ≈ 40 ps • InGaAs/InP: η = 20% @ 1550 nm, d ≈ 10 kHz, Δt ≈ 400 ps, τ = 10 μs, high excess noise, gating necessary

  8. Hamamatsu Hybrid photodetectors • combination of a photocathode with avalanche photodiode • low excess noise due to single large-amplification step • η = 46% @ 500 nm, d ≈ 1 kHz, Δt ≈ 35 ps

  9. Albota et al., OL 29, 1449 (2004)Langrock et al., OL 30, 1725 (2005) 1550 nm 630 nm 1064 nm Frequency up-conversion • conversion of IR-photons to a region with better detectors • PPLN: 90% conversion • very intense pumping needed (cavity or waveguide) • high-noise (background nonlinear processes emitting at target wavelength due to strong pumping) • η = 46% @ 1550 nm, d ≈ 800 kHz, Δt ≈ 400 ps (thick junction Si SPAD) • coherent up-conversion is feasible

  10. Kim et al., APL 74, 902 (1999)Takeuchi et al., APL 74, 1063 (1999) Visible-light photon counters (VLPC) • controlled single-carrier multiplication process @ 6K temperature • avalanche triggered by a hole in As-doped region confined to  20 μm • resolves up to 5 photons • ηconv = 88% @ 694 nm (ηconv = 93% @ near IR), d ≈ 20 kHz, Δt ≈ 250 ps, τ = 100 ns Figure by Y. Yamamoto

  11. Cabrera et al., APL 73, 735 (1998)Rosenberg et al., PRA 71, 061803 (2005)Lita et al., OE 16, 3032 (2008) Transition-edge sensors • superconduction film (W) kept at the temperature of superconducting transition (100 mK) • photon-absorbtion induced temperature change is detected as a current change • resolves up to 8 photons • η = 95% @ 1550 nm, d ≈ 3 Hz, Δt ≈ 100 ns, τ = 2 μs • can be done at anywavelength between200-1800 nm

  12. Goltsman et al., APL 79, 705 (2001)Marsili et al., NJP 11, 045022 (2009) Superconducting nanowires • 100 nm wide nanowire in a thin superconducting film • NbN @ 1.5-4K (below superconducting transition) • wire biased just below critical current • photon detections create resistive hotspots and trigger voltage pulses • η = 1-57% @ 1550 nm, d ≈ 10 Hz, Δt ≈ 30-60 ps,τ = 10ns (large area) • deposition of structures for spatial multiplexing possible • improvements likely

  13. Rowe et al., APL 89, 253505 (2006)Kardynal et al., APL 90, 181114 (2007)Blakesleyet al., PRL 94, 067401 (2005) Quantum dots or defects • trapping of charge in defects • heterostructures based on III-V compounds • trapped charge alters conductance in a field-effect transistor (ηconv = 68% @ 805 nm, resolves up to 3 photons) • alters tunneling probabilityin a resonant tunnel diode (ηconv = 12% @ 550 nm, d = 2x10-3 Hz) • 4K temperature needed • improvements likely

  14. Ambrosio et al., NIMPRA 617, 378 (2010) Carbon nanotubes (?) • multi-wall carbon nanotubes are grown (CVD) on p-doped silicon substrate • structure behaves like a photodiode with η≈50%

  15. Multichannel detectors • [VLPC, HD, nanowires] • Fiber-loops • Solid state photomultipliers • i-CCD cameras • EM-CCD cameras

  16. Haderka et al., EPJD 28, 149 (2004)Fitch et al., PRA 68, 043814 (2003) Fiber loops

  17. Hamamatsu Multi-pixel photon counter (silicon photomultiplier) • array of APDs in Geiger mode • currently 100 – 1600 pixels • crosstalk due to back-flashes • η = 65% @ 440 nm, d = 6 x 105 Hz, Δt ≈ 200-300 ps

  18. η = 25% @ 550 nm, d ~ 104 Hz, Δt ≈ 2 ns AndorRoper ScientificHamamatsu iCCD cameras

  19. AndorRoper ScientificHamamatsu EM-CCD (L3) cameras • high η of back-illuminated CCDs • single photon sensitivity • CIC noise • ‘slow’ shutter • η = 97% @ 550 nm

  20. Figures of merit For binary detectors: efficiency factor Qeff For photon-number resolving detectors: peak-to-valley contrast number of resolvable peaks effective number of channels n-photon fidelity

  21. Detector comparison chart [Qeff]

  22. Detector comparison chart [ENC]

  23. n-photon fidelity

  24. Olomouc: Application of single-photon detectors to twin photon beams • Characterization of photon-number correlations • Spatial correlations • Absolute quantum efficiency measurement • Noise reduction techniques

  25. Λs Φs L θs τ θs0 w Λp θi0 θi Φi Λi Type-I spontaneous parametric down-conversion

  26. Generation and measurement of photon twins

  27. Detection with iCCD camera signal strip noise reference summed image idler strip

  28. Haderka et al., PRA 71, 033815 (2005) Photon-number correlations

  29. Spatial correlations

  30. Spatial correlations:varying the pump beam spectrum Spatial spectrum of the pump beam Temporal pump-field spectrum Experimental radial cross-section of the correlation area Experimental angular cross-section of the correlation area

  31. Spatial correlations:varying the pump beam shape

  32. CONCLUSION • Single photon detection technology makes big leaps • Promising nanotechnologies appear • Both intrinsic and multichannel photon-number resolution improves • This all should contribute to present & future quantum information systems

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