Free-running InGaAs single photon detector with 1 dark count per second at 10% efficiency

B. Korzh, N. Walenta, T. Lunghi, N. Gisin, H. Zbinden
2014 Applied Physics Letters  
We present a free-running single photon detector for telecom wavelengths based on a negative feedback avalanche photodiode (NFAD). A dark count rate as low as 1 cps was obtained at a detection efficiency of 10%, with an afterpulse probability of 2.2% for 20 {\mu}s of deadtime. This was achieved by using an active hold-off circuit and cooling the NFAD with a free-piston stirling cooler down to temperatures of -110${^o}$C. We integrated two detectors into a practical, 625 MHz clocked quantum key
more » ... locked quantum key distribution system. Stable, real-time key distribution in presence of 30 dB channel loss was possible, yielding a secret key rate of 350 bps.
doi:10.1063/1.4866582 fatcat:p2e3tg773fechcalwrnr2cnojy