Geometrical Jitter and Bolometric Regime in Photon Detection by Straight Superconducting Nanowire

Abstract

We present a direct observation of the geometrical jitter in single photon detection by a straight superconducting nanowire. Differential measurement technique was applied to the 180-µm long nanowire similar to those commonly used in the technology of superconducting nanowire single photon detectors (SNSPD). A non-gaussian geometrical jitter appears as a wide almost uniform probability distribution (histogram) of the delay time (latency) of the nanowire response to detected photon. White electrical noise of the readout electronics causes broadened, Gaussian shaped edges of the histogram. Subtracting noise contribution, we found for the geometrical jitter a standard deviation of ≈8.5 ps and the full width at half maximum (FWHM) of the distribution of ≈29 ps. FWHM corresponds to the propagation speed of the electrical signal along the nanowire of ≈6.2×10 6 m/s or 0.02 of the speed of light. Alternatively the propagation speed was estimated from the central frequency of the measured first order self-resonance of the nanowire. Both values agree well with each other and with previously reported values. As the intensity of the incident photon flux increases, the wide probability distribution collapses into a much narrower Gaussian distribution with a standard deviation dominated by the noise of electronics. We associate the collapse of the histogram with the transition from the discrete, single photon detection to the uniform bolometric regime.

Efficient Single-Photon Detection with 7.7 ps Time Resolution for Photon-Correlation Measurements

“…We also measured the time jitter for some pixels of the array, the results of one such measurement are provided in Figure c. The measured system jitter of 23 ps for a ∼4.46 mm long detector is >25× better than other platforms, − even considering only the geometrical jitter, which indicates that the electromagnetic field does not have as high a confinement in our platform as detectors made from thinner films (capacitive coupling of signal between the lines).…”

Room-temperature photoconductivity in superconducting tungsten meander wires

“…In another scenario, the superconducting nanowires (SCNWs) 10,11,[16][17][18][19][20] have impressive photodetection and bolometric application capabilities with low noise and minimum energy requirement in comparison to semiconducting materials and others but are limited due to the need for their low temperature-based cryogenic operation/measurements in terms of technological application. In this category, 10,11,[16][17][18][19][20] ion beamfabricated meander structures of SCNWs have also been reported for single photon detector (SPD) applications. They provide a larger surface area with a small channel for current flow, and easy accessibility to photodetection process.…”

A platform for high performance photon correlation measurements

“…We also measured the time jitter for some pixels of the array, the results of one such measurement is provided in Figure 4(c). The measured system jitter of 23 ps for a ∼4.46 mm long detector is >25 times better than other platforms [33][34][35] even considering only the geometrical jitter, which indicates that the electromagnetic field does not have as high confinement in our platform as detectors made from thinner films (capacitive coupling of signal between the lines).…”