Minimal timing jitter in superconducting nanowire single photon detectors

TL;DR

This paper models the timing jitter in superconducting nanowire single photon detectors, showing it can be minimized to fundamental limits by optimizing current and photon absorption position.

Contribution

It introduces a coupled two-temperature and Ginzburg-Landau model to analyze delay times and jitter in SNSPDs, revealing conditions for minimal timing uncertainty.

Findings

Timing jitter depends on photon absorption position and current.

Jitter can be as low as the superconductor's fundamental relaxation time.

Optimal conditions occur near the depairing current.

Abstract

Using two-temperature model coupled with modified time-dependent Ginzburg-Landau equation we calculate the delay time $\tau_d$ in appearance of growing normal domain in the current-biased superconducting strip after absorption of the single photon. We demonstrate that $\tau_d$ depends on the place in the strip where photon is absorbed and monotonically decreases with increasing of the current. We argue, that the variation of $\tau_d$ (timing jitter), connected either with position-dependent response or Fano fluctuations could be as small as the lowest relaxation time of the superconducting order parameter $\sim \hbar/k_BT_c$ ($T_c$ is the critical temperature of the superconductor) when the current approaches the depairing current.