A hybrid superconductor-normal metal electron trap as a photon detector

TL;DR

This paper demonstrates a hybrid superconductor-normal metal electron trap functioning as a photon detector, revealing photon-assisted electron escape influenced by nearby SET B, with implications for low-temperature noise spectrometry and quantum standards.

Contribution

It introduces a novel hybrid electron trap device that detects photons via electron escape, advancing photon detection techniques at low temperatures.

Findings

Photon-assisted electron escape rate depends on SET B voltage.

Photon emission occurs when photon energies exceed the superconducting gap.

The device has potential applications in noise spectrometry and quantum current standards.

Abstract

A single-electron trap built with two Superconductor (S) - Insulator (I) - Normal (N) metal tunnel junctions and coupled to a readout SINIS-type single-electron transistor A (SET A) was studied in a photon detection regime. As a source of photon irradiation, we used an operating second SINIS-type SET B positioned in the vicinity of the trap. In the experiment, the average hold time of the trap was found to be critically dependent on the voltage across SET B. Starting in a certain voltage range, a photon-assisted electron escape was observed at a rate roughly proportional to the emission rate of the photons with energies exceeding the superconducting gap of S-electrodes in the trap. The discussed mechanism of photon emission and detection is of interest for low-temperature noise spectrometry and it can be of relevance for the ampere standard based on hybrid SINIS turnstiles.