Revealing spoofing of quantum illumination using entanglement

TL;DR

This paper investigates the vulnerability of quantum illumination radar to spoofing attacks and demonstrates that entanglement provides a unique resource for detecting such spoofing attempts.

Contribution

It introduces a framework for analyzing quantum radar spoofing and shows how entanglement enhances spoof detection capabilities compared to classical methods.

Findings

Direct detection spoofing produces higher fidelity, making spoofs harder to detect.

Entanglement improves spoof detection even with noise and loss.

Quantum radar can distinguish true signals from spoofed ones using hypothesis testing.

Abstract

Several quantum radar concepts have been proposed that exploit the entanglement found in two-mode squeezed vacuum states of the electromagnetic field, the most prominent being radar based on quantum illumination. Classical radars are sometimes required to distinguish between true echos of their transmitted signals and signals generated by interferors or spoofers. How vulnerable to spoofing is quantum illumination? We analyze the scenario of a radar operator trying to detect the presence of a classical spoofer employing a measure-and-prepare strategy against a quantum radar. We consider two spoofing strategies - (1) direct detection and number state preparation, and (2) heterodyne detection and coherent state preparation. In each case, the radar operator performs a hypothesis test to decide if received pulses are true returns or spoofs. Since the spoofer can not reproduce the entanglement with modes retained by the radar operator, both approaches to spoofing are to some extent detectable. We quantify the effectiveness of the spoof in terms of the fidelity between the real return and the spoof return, and the probability of error in spoof detection. We find that in the absence of noise and loss, direct detection tends to produce spoofs with greater fidelity, which are therefore harder to detect. Moreover, this advantage survives the introduction of noise and loss into the model. Our results suggest that entanglement is a novel resource available to quantum radar for detecting spoofing.