Weak-Link Phenomena in AC-Biased Transition Edge Sensors

TL;DR

This paper investigates the weak-link behavior in AC-biased superconducting transition edge sensors (TESs) and its effects on TES-based bolometers and microcalorimeters, using a specific TiAu TES for space telescope applications.

Contribution

It provides a detailed analysis of weak-link phenomena in AC-biased TESs and explores their implications for high-frequency readout in bolometers and microcalorimeters.

Findings

Weak-link behavior affects TES performance under AC bias.

The study demonstrates the use of a Frequency Domain Multiplexer with high-Q resonators.

The TiAu TES achieved a dark NEP of 3.2×10^{-19} W/Hz^{1/2}.

Abstract

It has been recently demonstrated that superconducting transition edge sensors (TESs) behave as weak-links due to longitudinally induced superconductivity from the leads with higher Tc. In this work we study the implication of this behaviour for TES-based bolometers and microcalorimeter under ac bias. The TESs are read-out at frequencies between 1 and 5 MHz by a Frequency Domain Multiplexer based on a linearised two-stage SQUID amplifier and high- Q lithographically made superconducting LC resonators. In particular, we focus on SRON TiAu TES bolometers with a measured dark Noise Equivalent Power (NEP) of $3.2 \cdot 10^{-19} W/Hz^{1/2}$ developed for the short wavelength band for the instrument SAFARI on the SPICA telescope.