Quantum Illumination at the Microwave Wavelengths

TL;DR

This paper demonstrates a microwave quantum illumination system that uses entanglement and joint detection to improve target detection in thermal backgrounds, outperforming classical radar at the same energy level.

Contribution

It introduces a microwave quantum illumination method utilizing electro-optomechanical conversion and joint detection, advancing quantum sensing at microwave frequencies.

Findings

Error probability is lower than classical radar.

System effectively detects low-reflectivity objects.

Quantum advantage demonstrated at microwave frequencies.

Abstract

Quantum illumination is a quantum-optical sensing technique in which an entangled source is exploited to improve the detection of a low-reflectivity object that is immersed in a bright thermal background. Here we describe and analyze a system for applying this technique at microwave frequencies, a more appropriate spectral region for target detection than the optical, due to the naturally-occurring bright thermal background in the microwave regime. We use an electro-optomechanical converter to entangle microwave signal and optical idler fields, with the former being sent to probe the target region and the latter being retained at the source. The microwave radiation collected from the target region is then phase conjugated and upconverted into an optical field that is combined with the retained idler in a joint-detection quantum measurement. The error probability of this microwave quantum-illumination system, or quantum radar, is shown to be superior to that of any classical microwave radar of equal transmitted energy.