Experimental Quantum Target Detection Approaching the Fundamental Helstrom Limit

TL;DR

This paper demonstrates an experimental quantum illumination technique that surpasses classical detection limits and approaches the Helstrom quantum limit, showcasing the potential of entanglement-based sensing for improved target detection.

Contribution

The study provides the first experimental realization of quantum target detection approaching the Helstrom limit using single-photon quantum illumination.

Findings

Quantum advantage exists even in classical-futile regions.

Quantum illumination surpasses classical limits by up to 40%.

Approaches the fundamental Helstrom detection limit.

Abstract

Quantum target detection is an emerging application that utilizes entanglement to enhance the sensing of the presence of an object. Although several experimental demonstrations for certain situations have been reported recently, the single-shot detection limit imposed by the Helstrom limit has not been reached because of the unknown optimum measurements. Here we report an experimental demonstration of quantum target detection, also known as quantum illumination, in the single-photon limit. In our experiment, one photon of the maximally entangled photon pair is employed as the probe signal and the corresponding optimum measurement is implemented at the receiver. We explore the detection problem in different regions of the parameter space and verify that the quantum advantage exists even in a forbidden region of the conventional illumination, where all classical schemes become useless. Our results indicate that quantum illumination breaks the classical limit for up to 40%, while approaching the quantum limit imposed by the Helstrom limit. These results not only demonstrate the advantage of quantum illumination, but also manifest its valuable potential of target detection.