Performance of coherent-state quantum target detection in the context of asymmetric hypothesis testing

TL;DR

This paper examines the effectiveness of coherent-state quantum target detection in quantum radar, highlighting limitations of current theoretical methods in demonstrating quantum advantage in practical finite-size scenarios.

Contribution

It analyzes the performance of quantum-inspired coherent-state detection schemes using asymmetric hypothesis testing and reveals the insufficiency of second- and third-order expansions for finite regimes.

Findings

Second- and third-order expansions are inadequate for finite-size regimes.

Quantum advantage is difficult to establish with current asymptotic methods.

Coherent-state schemes have practical limitations in quantum radar applications.

Abstract

Due to the difficulties of implementing joint measurements, quantum illumination schemes that are based on signal-idler entanglement are difficult to implement in practice. For this reason, one may consider quantum-inspired designs of quantum lidar/radar where the input sources are semiclassical (coherent states) while retaining the quantum aspects of the detection. The performance of these designs could be studied in the context of asymmetric hypothesis testing by resorting to the quantum Stein's lemma. However, here we discuss that, for typical finite-size regimes, the second- and third-order expansions associated with this approach are not sufficient to prove quantum advantage.