  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.
