Super-Resolving Quantum Radar: Coherent-State Sources with Homodyne Detection Suffice to Beat the Diffraction Limit

TL;DR

This paper demonstrates that using coherent-state sources combined with homodyne detection can achieve super-resolution beyond the diffraction limit in quantum radar, maintaining shot-noise sensitivity even in high-loss atmospheric conditions.

Contribution

It introduces a practical quantum radar approach utilizing coherent states and homodyne detection to surpass the diffraction limit with existing technology.

Findings

Achieves super-resolution below Rayleigh limit

Maintains shot-noise sensitivity in high-loss environments

Provides a feasible template for quantum radar development

Abstract

There has been much recent interest in quantum metrology for applications to sub-Raleigh ranging and remote sensing such as in quantum radar. For quantum radar, atmospheric absorption and diffraction rapidly degrades any actively transmitted quantum states of light, such as N00N states, so that for this high-loss regime the optimal strategy is to transmit coherent states of light, which suffer no worse loss than the linear Beer's law for classical radar attenuation, and which provide sensitivity at the shot-noise limit in the returned power. We show that coherent radar radiation sources, coupled with a quantum homodyne detection scheme, provide both longitudinal and angular super-resolution much below the Rayleigh diffraction limit, with sensitivity at shot-noise in terms of the detected photon power. Our approach provides a template for the development of a complete super-resolving quantum radar system with currently available technology.