Intrinsic Timing Jitter and Latency in Superconducting Nanowire Single-photon Detectors

Abstract

We analyze the origin of the intrinsic timing jitter in superconducting nanowire single photon detectors (SNSPDs) in terms of fluctuations in the latency of the detector response, which is determined by the microscopic physics of the photon detection process. We demonstrate that fluctuations in the physical parameters which determine the latency give rise to the intrinsic timing jitter. We develop a general description of latency by introducing the explicit time dependence of the internal detection efficiency. By considering the dynamic Fano fluctuations together with static spatial inhomogeneities, we study the details of the connection between latency and timing jitter. We develop both a simple phenomenological model and a more general microscopic model of detector latency and timing jitter based on the solution of the generalized time-dependent Ginzburg-Landau equations for the 1D hotbelt geometry. While the analytical model is sufficient for qualitative interpretation of recent data, the general approach establishes the framework for a quantitative analysis of detector latency and the fundamental limits of intrinsic timing jitter. These theoretical advances can be used to interpret the results of recent experiments measuring the dependence of detection latency and timing jitter on photon energy to the few-picosecond level.

Minimal Timing Jitter in Superconducting Nanowire Single-Photon Detectors

“…We find, that τ d is drastically reduced as the current approaches to the depairing current and timing jitter may be as small as /k B T c (∼ 0.8 ps for superconductor with T c = 10K). We also show that the considered model with position-dependent response predicts stronger deviation of dependence of photon counts on the delay time (in the literature its is called as probability density function (PDF) [4] or instrument response function (IRF) [6,9]) from the Gaussian-like distribution than the hot belt model predicts [9]. We argue that it occurs due to photons absorbed near the edge of the strip which provide the largest delay time.…”

“…We follow the Ref. [9] and introduce normalized probability of energy deposition E both to electron and phonon systems after ab- sorption of the photon…”

“…In this paper, based on the two-temperature model coupled with modified time-dependent Ginzburg-Landau equation and current continuity equation [7] we calculate the position-dependent delay time in SNSPD both in absence and in presence of Fano fluctuations and study how τ d depends on the current and deposited energy. Effect of Fano fluctuations in our model are taken into account via introduction of probability P (E) to deposit energy E < E ν to the electron/phonon systems of superconductor [8,9]. Effect of variations of material parameters may be considered in a similar way [9] and we do not study them explicitly.…”

“…Effect of Fano fluctuations in our model are taken into account via introduction of probability P (E) to deposit energy E < E ν to the electron/phonon systems of superconductor [8,9]. Effect of variations of material parameters may be considered in a similar way [9] and we do not study them explicitly. We define the delay time τ d as a time needed for formation of the growing normal domain after absorption of the photon somewhere in the superconducting strip.…”

Jitter Characterization of a Dual-Readout SNSPD

“…The larger hotspot jitter at 4.5 K is presumably related to larger thermal fluctuations leading to greater variation in the hotspot formation process. Recent theoretical work has sought to quantify the effects of Fano fluctuations, variation in the photon absorption location across the width of the nanowire, and nanowire spatial inhomogeneity on the jitter [9], [10]. None of these mechanisms seem to be able to explain the large temperature dependence seen in J hotspot .…”