Classical benchmarking for microwave quantum illumination

TL;DR

This paper establishes the true classical benchmark for microwave quantum illumination using coherent states, providing new bounds and ROC formulas, and proposes a practical source generation method for room temperature quantum detection.

Contribution

It defines the classical benchmark for microwave QI, derives new error bounds and ROC formulas, and introduces a feasible coherent state source for practical applications.

Findings

New bounds on error probability for microwave QI

Closed-form ROC expressions for detection schemes

Proposed coherent state source for practical microwave quantum detection

Abstract

Quantum illumination (QI) theoretically promises up to a 6dB error-exponent advantage in target detection over the best classical protocol. The advantage is maximised by a regime which includes a very high background, which occurs naturally when one considers microwave operation. Such a regime has well-known practical limitations, though it is clear that, theoretically, knowledge of the associated classical benchmark in the microwave is lacking. The requirement of amplifiers for signal detection necessarily renders the optimal classical protocol here different to that which is traditionally used, and only applicable in the optical domain. In this work we outline what is the true classical benchmark for microwave QI using coherent states, providing new bounds on the error probability and closed formulae for the receiver operating characteristic (ROC), for both optimal (based on quantum relative entropy) and homodyne detection schemes. We also propose an alternative source generation procedure based on coherent states which demonstrates potential to reach classically optimal performances achievable in optical applications. We provide the same bounds and measures for the performance of such a source and discuss its potential utility in the future of room temperature quantum detection schemes in the microwave.