Ultimate accuracy limit of quantum pulse-compression ranging

TL;DR

This paper derives the ultimate quantum limit on radar ranging accuracy and shows that quantum illumination (QI) ranging can surpass classical radar performance by significant margins using entanglement.

Contribution

It establishes the fundamental quantum limit on radar ranging accuracy and demonstrates that QI ranging achieves this limit, outperforming classical pulse-compression radar.

Findings

QI ranging can be 10's of dB more accurate than classical radar.

The quantum limit on ranging accuracy is derived through continuous-time quantum analysis.

QI exploits entanglement between signal and idler pulses for enhanced precision.

Abstract

Radars use time-of-flight measurement to infer the range to a distant target from its return's roundtrip range delay. They typically transmit a high time-bandwidth product waveform and use pulse-compression reception to simultaneously achieve satisfactory range resolution and range accuracy under a peak transmitted-power constraint. Despite the many proposals for quantum radar, none have delineated the ultimate quantum limit on ranging accuracy. We derive that limit through continuous-time quantum analysis and show that quantum illumination (QI) ranging -- a quantum pulse-compression radar that exploits the entanglement between a high time-bandwidth product transmitted signal pulse and and a high time-bandwidth product retained idler pulse -- achieves that limit. We also show that QI ranging offers mean-squared range-delay accuracy that can be 10's of dB better than a classical pulse-compression radar's of the same pulse bandwidth and transmitted energy.