Probability of the resistive state formation caused by absorption of a   single-photon in current-carrying superconducting nano-strips
  We have studied supercurrent-assisted formation of the resistive state in nano-structured Nb and NbN superconducting films after absorption of a single photon. In amorphous narrow NbN strips the probability of the resistive state formation has a pronounced spectral cut-off. The corresponding threshold photon energy decreases with the bias current. Analysis of the experimental data in the framework of the generalized hot-spot model suggests that the quantum yield for near-infrared photons increases faster than the photon nergy. Relaxation of the resistive state depends on the photon energy making the phenomenon feasible for the development of energy resolving single-photon detectors. 
Alexei Semenov (1), Andreas Engel (1), Heinz-Wilhelm H\"ubers (1),   Konstantin Ilin (2), Michael Siegel (2) ((1) DLR Instit...