Thermoelectric radiation detector based on a superconductor-ferromagnet junction: calorimetric regime

TL;DR

This paper explores a superconductor-ferromagnet thermoelectric junction as a highly sensitive calorimetric radiation detector capable of single-photon detection at THz frequencies, leveraging high figure of merit and multiplexing techniques.

Contribution

It introduces a novel thermoelectric detector design with high $ZT$, detailed noise modeling, and multiplexing strategies for efficient single-photon detection at low temperatures.

Findings

Energy resolution as low as 1 meV at 100-200 mK

Potential for broadband single-photon detection below 1 THz

High thermoelectric figure of merit enhances detector performance

Abstract

We study the use of a thermoelectric junction as a thermal radiation detector in the calorimetric regime, where single radiation bursts can be separated in time domain. We focus especially on the case of a large thermoelectric figure of merit $ZT$ affecting significantly for example the relevant thermal time scales. This work is motivated by the use of hybrid superconductor/ferromagnet systems in creating an unprecedentedly high low-temperature $ZT$ even exceeding unity. Besides constructing a very general noise model which takes into account cross correlations between charge and heat noise, we show how the detector signal can be efficiently multiplexed by the use of resonant LC circuits giving a fingerprint to each pixel. We show that for realistic detectors operating at temperatures around 100 to 200 mK, the energy resolution can be as low as 1 meV. This allows for a broadband single-photon resolution at photon frequencies of the order or below 1 THz.