Timing jitter in photon detection by straight superconducting nanowires: Effect of magnetic field and photon flux

TL;DR

This study investigates how magnetic fields and photon flux influence timing jitter in superconducting nanowire photon detectors, revealing mode transitions and electron fluctuation effects that impact detection precision.

Contribution

It provides new insights into the effects of magnetic field and photon flux on timing jitter and mode transitions in superconducting nanowire photon detectors.

Findings

Magnetic field increases exponential tail time in jitter distribution.

Higher photon flux transitions detector from quantum to bolometric mode, reducing jitter.

Electron-number fluctuations correlate with the Gaussian part of the timing distribution.

Abstract

We studied the effect of the external magnetic field and photon flux on timing jitter in photon detection by straight superconducting NbN nanowires. At two wavelengths 800 and 1560 nm, statistical distribution in the appearance time of the photon count exhibits Gaussian shape at small times and exponential tail at large times. The characteristic exponential time is larger for photons with smaller energy and increases with external magnetic field while variations in the Gaussian part of the distribution are less pronounced. Increasing photon flux drives the nanowire from quantum detection mode to the bolometric mode that averages out fluctuations of the total number of nonequilibrium electrons created by the photon and drastically reduces jitter. The difference between Gaussian parts of distributions for these two modes provides the measure for the electron-number fluctuations. Corresponding standard deviation increases with the photon energy. We show that the two-dimensional hot-spot detection model explains qualitatively the effect of magnetic field.