Microwave Quantum Illumination with Optical Memory and Single-Mode Phase-Conjugate Receiver

TL;DR

This paper proposes a microwave quantum illumination system with optical memory and a novel phase-conjugate receiver, demonstrating quantum advantage robustness against memory loss and practical detection methods.

Contribution

It introduces a testbed with optical memory simulated by a delay line and a single-mode phase conjugate receiver, advancing practical quantum illumination techniques.

Findings

Quantum advantage maintained with optical memory loss.

High input two-mode squeezing needed for lossy memory.

Receiver performance approaches maximum quantum advantage.

Abstract

Microwave quantum illumination with entangled pairs of microwave signal and optical idler modes, can achieve the sub-optimal performance with joint measurement of the signal and idler modes. Here, we first propose a testbed of microwave quantum illumination with an optical memory which is simulated with a delay line in the idler mode. It provides how much an input two-mode squeezing is necessary to compensate the loss of the optical memory, while maintaining quantum advantage over coherent state. When the memory is lossy, the input two-mode squeezing has to be higher through high cooperativity in the optical mode. Under the testbed, we propose a single-mode phase conjugate receiver that consists of a low-reflectivity beam splitter, an electro-optomechanical phase conjugator, and a photon number resolving detector. The performance of the newly proposed receiver approaches the maximum quantum advantage for local measurement. Furthermore, the quantum advantage is obtained even with an on-off detection while being robust against the loss of the memory.