Enhancing the sensitivity of single microwave photon detection with bandwidth tunability

TL;DR

This paper presents a superconducting transmon qubit-based microwave photon counter with bandwidth tunability, achieving high sensitivity and optimized efficiency for single microwave photon detection.

Contribution

Introduction of a bandwidth tuning circuit in a superconducting microwave photon counter, enhancing efficiency and noise performance compared to previous designs.

Findings

Achieved power sensitivity of 3 x 10^{-23} W/√Hz.

Demonstrated high performance via single spin microwave fluorescence measurement.

Device fabrication improvements contributed to performance enhancement.

Abstract

We report on the characteristics of a microwave photon counter device based on a superconducting transmon qubit. Its design is similar to [arXiv:2307.03614], with an additional bandwidth tuning circuit that allows optimizing the device efficiency and noise. Owing to this new feature and to improvements in device fabrication, a power sensitivity of $3 \cdot 10^{-23} \mathrm{W}/\sqrt{\mathrm{Hz}}$ is reached. We confirm the high performance of the device by measuring single spin microwave fluorescence.