Development of highly sensitive nanoscale transition edge sensors for gigahertz astronomy and dark matter search

TL;DR

This paper introduces a nanoscale transition edge sensor (nano-TES) with enhanced sensitivity for gigahertz astronomy and dark matter detection, featuring innovative design and promising performance metrics.

Contribution

It presents a novel aluminum/copper bilayer nano-TES with optimized thermal properties and heat confinement, achieving state-of-the-art sensitivity for sub-THz applications.

Findings

Predicted NEP of 5×10⁻²⁰ W/√Hz for bolometric operation

Relaxation time of approximately 10 ns suitable for CMB studies

Frequency resolution of 100 GHz as a single-photon sensor

Abstract

Terahertz and sub-terahertz band detection has a key role both in fundamental interactions physics and technological applications, such as medical imaging, industrial quality control and homeland security. In particular, transition edge sensors (TESs) and kinetic inductance detectors (KIDs) are the most employed bolometers and calorimeters in the THz and sub-THz band for astrophysics and astroparticles research. Here, we present the electronic, thermal and spectral characterization of an aluminum/copper bilayer sensing structure that, thanks to its thermal properties and a simple miniaturized design, could be considered a perfect candidate to realize an extremely sensitive class of nanoscale TES (nano-TES) for the giga-therahertz band. Indeed, thanks to the reduced dimensionality of the active region and the efficient Andreev mirror (AM) heat confinement, our devices are predicted to reach state-of-the-art TES performance. In particular, as a bolometer the nano-TES is expected to have a noise equivalent power (NEP) of $5\times10^{-20}$ W/$\sqrt{\mathrm{Hz}}$ and a relaxation time of $\sim 10$ ns for the sub-THz band, typical of cosmic microwave background studies. When operated as single-photon sensor, the devices are expected to show a remarkable frequency resolution of 100 GHz, pointing towards the necessary energy sensitivity requested in laboratory axion search experiments. Finally, different multiplexing schemes are proposed and sized for imaging applications.