PT Unknown
AU Verevkin, AA
   Zhang, J
   Slysz, W
   Sobolewski, R
   Lipatov, AP
   Okunev, O
   Chulkova, G
   Korneev, A
   Gol’tsman, GN
TI Superconducting single-photon detectors for GHz-rate free-space quantum communications
SE Proc. SPIE
PY 2002
BP 447
EP 454
VL 4821
DI 10.1117/12.453542
DE NbN SSPD; SNSPD; single-photon detector; thin-film superconductivity; quantum cryptography; ultrafast communications
AB We report our studies on the performance of new NbN ultrathin-film superconducting single-photon detectors (SSPDs). Our SSPDs exhibit experimentally measured quantum efficiencies from   5% at wavelength λ = 1550 nm up to  10% at λ = 405 nm, with exponential, activation-energy-type spectral sensitivity dependence in the 0.4-μm - 3-μm wavelength range. Using a variable optical delay setup, we have shown that our NbN SSPDs can resolve optical photons with a counting rate up to 10 GHz, presently limited by the read-out electronics. The measured device jitter was below 35 ps under optimum biasing conditions. The extremely high photon counting rate, together with relatively high (especially for λ > 1 μm) quantum efficiency, low jitter, and very low dark counts, make NbN SSPDs very promising for free-space communications and quantum cryptography.
ER