Fully superconducting Josephson bolometers for gigahertz astronomy

TL;DR

This paper reviews the design and experimental testing of fully superconducting Josephson junction-based bolometers, nano-TES and JES, with ultra-sensitive detection capabilities for gigahertz astronomy, aiming to advance cosmic background radiation studies.

Contribution

It introduces two novel bias-current-tunable superconducting sensors, nano-TES and JES, with record-breaking noise equivalent power for gigahertz astronomical detection.

Findings

Nano-TES achieves NEP of about 5×10⁻²⁰ W/√Hz.

JES is expected to reach NEP of around 10⁻²⁵ W/√Hz.

Sensors show promising potential for next-generation radio astronomy.

Abstract

The origin and the evolution of the universe are concealed in the evanescent diffuse extragalactic background radiation (DEBRA). To reveal these signals, the development of innovative ultra-sensitive bolometers operating in the gigahertz band is required. Here, we review the design and experimental realization of two bias-current-tunable sensors based on one dimensional fully superconducting Josephson junctions: the nanoscale transition edge sensor (nano-TES) and the Josephson escape sensor (JES). In particular, we cover the theoretical basis of the sensors operation, the device fabrication, their experimental electronic and thermal characterization, and the deduced detection performance. Indeed, the nano-TES promises a state-of-the-art noise equivalent power (NEP) of about $5 \times 10^{-20}$ W$/\sqrt{\text{Hz}}$, while the JES is expected to show an unprecedented NEP of the order of $10^{-25}$ W$/\sqrt{\text{Hz}}$. Therefore, the nano-TES and JES are strong candidates to push radio astronomy to the next level.