Quantum Estimation Methods for Quantum Illumination

TL;DR

This paper applies quantum estimation techniques to quantum illumination, demonstrating improved detection performance and extending protocols to non-Gaussian states like Schrödinger's cat states.

Contribution

It introduces a quantum estimation framework for quantum illumination, achieving up to 3 dB signal-to-noise ratio enhancement with local measurements and extending the protocol to non-Gaussian states.

Findings

Achieved up to 3 dB SNR improvement over classical methods.

Provided a concrete estimator saturating the quantum Fisher information bound.

Extended quantum illumination to non-Gaussian states such as Schrödinger's cat states.

Abstract

Quantum illumination consists in shining quantum light on a target region immersed in a bright thermal bath, with the aim of detecting the presence of a possible low-reflective object. If the signal is entangled with the receiver, then a suitable choice of the measurement offers a gain with respect to the optimal classical protocol employing coherent states. Here, we tackle this detection problem by using quantum estimation techniques to measure the reflectivity parameter of the object, showing an enhancement in the signal-to-noise ratio up to 3 dB with respect to the classical case when implementing only local measurements. Our approach employs the quantum Fisher information to provide an upper bound for the error probability, supplies the concrete estimator saturating the bound, and extends the quantum illumination protocol to non-Gaussian states. As an example, we show how Schrodinger's cat states may be used for quantum illumination.