Energy resolution of terahertz single-photon-sensitive bolometric detectors

TL;DR

This paper measures the energy resolution of superconducting titanium nanobridge bolometers for single-photon detection in the terahertz range, demonstrating near-thermal fluctuation noise limits.

Contribution

It introduces a calibration technique using microwave pulses to accurately assess the energy resolution of terahertz single-photon-sensitive bolometers.

Findings

Energy resolution of ~23 THz achieved

Calibration method using microwave pulses

Resolutions close to thermal fluctuation noise limit

Abstract

We report measurements of the energy resolution of ultra-sensitive superconducting bolometric detectors. The device is a superconducting titanium nanobridge with niobium contacts. A fast microwave pulse is used to simulate a single higher-frequency photon, where the absorbed energy of the pulse is equal to the photon energy. This technique allows precise calibration of the input coupling and avoids problems with unwanted background photons. Present devices have an intrinsic full-width at half-maximum energy resolution of approximately 23 terahertz, near the predicted value due to intrinsic thermal fluctuation noise.