Quantum detection by current carrying superconducting film

Numerical analysis of detection-mechanism models of superconducting nanowire single-photon detector

“…Absorption of such a photon results in a large number of excitations in the form of QPs and phonons. Details of this QP multiplication process have been already described in an early publication on SNSPD 30 and references therein. In this paper, we are not interested in the detailed time-evolution of the number of excited QPs, instead we will resort to a simple analytical approximation.…”

“…29 Despite this remarkable progress in understanding and optimization of SNSPD, some open questions remain, particularly in connection with the mechanism that is responsible for triggering the initial resistive cross-section. The first model 30 describing the detection mechanism in SNSPD assumed the formation of a normal-conducting hot-spot that diverts the applied bias current into the still superconducting side-walks. The current density in these side-walks will eventually increase beyond the critical current density, thereby leading to the initial normal-conducting cross-section.…”

Intrinsic quantum efficiency and electro-thermal model of a superconducting nanowire single-photon detector

“…Since the amplitude of the transient voltage is almost entirely controlled by the magnitude of the current, the detector cannot distinguish the number of simultaneously received photons. It has been predicted, that the hot-spot detection scenario has a cut-off in the single-photon detection capability [3] and an indication of this has been found recently [5]. However, due to the change of the detection mechanism for low-energy photons, SNSPD shows lower quantum efliciency *Corresponding author.…”

“…A possibility to resistively detect a single optical photon in a relatively large superconducting film was discussed by Kadin and Johnson [2] in the framework of the hot-spot approximation. Semenov et al [3] proposed the use of an almost critical current-bias in order to relax requirements on the width of a superconductor and to extend single-photon sensitivity to the infrared range. Using this approach, Gol'tsman et al [4] demonstrated detection of single optical photons by a superconducting nanowire single-photon dctcctor (SNSPD).…”

Current distribution in a parallel configuration superconducting strip-line detector

“…When a single infrared photon strikes the strip, a fast voltage pulse is triggered through supercurrent assisted hot-spot formation and can be recorded by room temperature electronics. 3 The same working principle can be applied to detect single molecules with E $ 20 keV in TOF-MS with superconducting strips of widths up to 1 lm and thicknesses between the range 10 -50 nm. 1, 4 The response time of the device is limited by the strip-line kinetic inductance, L k , which increases in proportion to the strip-line length.…”