Imperfect photon detection in quantum illumination

TL;DR

This paper analyzes the performance of photon detection schemes in quantum illumination, focusing on realistic parameters and the potential advantages of correlated photon counting under practical constraints.

Contribution

It provides a detailed assessment of detection efficiency, dark counts, and photon number resolution effects in microwave quantum illumination, including the benefits of correlated photon counting.

Findings

Photon number resolution requirements are highly asymmetric between mixer outputs.

Correlated photon counting can offer advantages under certain conditions.

Realistic detection parameters significantly impact quantum illumination performance.

Abstract

In quantum illumination, various detection schemes have been proposed for harnessing remaining quantum correlations of the entanglement-based resource state. To this date, the only successful implementation in the microwave domain relies on a specific mixing operation of the respective return and idler modes, followed by single-photon counting in one of the two mixer outputs. We investigate the performance of this scheme for realistic detection parameters in terms of detection efficiency, dark count probability, and photon number resolution. Furthermore, we take into account the second mixer output and investigate the advantage of correlated photon counting (CPC) for a varying thermal background and optimum post-processing weighting in CPC. We find that the requirements for photon number resolution in the two mixer outputs are highly asymmetric due to different associated photon number expectation values.