Quantum enhancement of spoofing detection with squeezed states of light

Using quantum state discrimination theory, we derive the upper bound for spoofing detection when randomly encoding two quantum states in an electromagnetic signal. We derive an analytic expression for the optimal bound and demonstrate that it can be saturated using a pair of coherent states. We show that quantum enhancement is independent of the number of photons; therefore, the single-photon restriction is unnecessary for experimental demonstration. We also consider encoding squeezed states in the signal and show that the detection probability approaches unity if the spoofer capability is limited to coherent state generation.