Detection of weak microwave fields with an underdamped Josephson junction

TL;DR

This paper presents a microwave detector utilizing an underdamped Josephson junction, capable of detecting single-photon microwave fields with high sensitivity, characterized through experimental measurements and theoretical analysis.

Contribution

The study introduces a novel microwave detection method based on Josephson junction voltage switching, demonstrating high sensitivity and detailed system characterization.

Findings

Achieved a sensitivity parameter of 0.5 for single-photon microwave detection.

Fully characterized the detector's efficiency and sensitivity across various conditions.

Experimental results qualitatively agree with theoretical predictions.

Abstract

We have constructed a microwave detector based on the voltage switching of an underdamped Josephson junction, that is positioned at a current antinode of a {\lambda}/4 coplanar waveguide resonator. By measuring the switching current and the transmission through a waveguide capacitively coupled to the resonator at different drive frequencies and temperatures we are able to fully characterize the system and assess its detection efficiency and sensitivity. Testing the detector by applying a classical microwave field with the strength of a single photon yielded a sensitivity parameter of 0.5 in qualitative agreement with theoretical calculations.