Ultra-Sensitive Hot-Electron Nanobolometers for Terahertz Astrophysics

TL;DR

This paper introduces superconducting hot-electron nanobolometers with ultra-low thermal conductance, enabling detection of single terahertz photons for advanced astrophysical observations.

Contribution

Development of superconducting hot-electron nanobolometers with quantum-limited thermal isolation for terahertz photon detection.

Findings

Electron-phonon thermal conductance less than 1% of quantum at T<0.1K

Nanobolometers capable of single THz photon detection

Potential applications in submillimeter astronomy

Abstract

The background-limited spectral imaging of the early Universe requires spaceborne terahertz (THz) detectors with the sensitivity 2-3 orders of magnitude better than that of the state-of-the-art bolometers. To realize this sensitivity without sacrificing operating speed, novel detector designs should combine an ultrasmall heat capacity of a sensor with its unique thermal isolation. Quantum effects in thermal transport at nanoscale put strong limitations on the further improvement of traditional membrane-supported bolometers. Here we demonstrate an innovative approach by developing superconducting hot-electron nanobolometers in which the electrons are cooled only due to a weak electron-phonon interaction. At T<0.1K, the electron-phonon thermal conductance in these nanodevices becomes less than one percent of the quantum of thermal conductance. The hot-electron nanobolometers, sufficiently sensitive for registering single THz photons, are very promising for submillimeter astronomy and other applications based on quantum calorimetry and photon counting.