Quantum remote sensing with atom-light entangled interface

Abstract

AbstractQuantum remote sensing utilizes quantum entanglement between the probe and the receiver to enhance the capability to sense a remote target. Quantum illumination is considered as a promising protocol to realize such a quantum technology in an environment of high loss and intense noise. However, the protocol requires an additional on-demand quantum memory, the imperfect performance of which diminishes the quantum advantage and limits the enhancement of sensing. In this paper, we propose a new protocol for quantum remote sensing based on quantum illumination with atom-light entangled interface. Compared to conventional light-only quantum illumination, the proposed protocol utilizes Raman coupling to create a long-lived atomic spin wave entangled with a Stokes light. The atomic spin wave, automatically built-in memory via the Raman coupling, acts as a local reference. The entangled Stokes light is used as a probe to irradiate a remote target. Meanwhile, the returned probe light from target is detected through coupling again to the atomic spin wave. A joint measurement on the returned probe light and spin wave is performed to discriminate the target. A 4 dB quantum enhancement over classical illumination is estimated. The atom-light entangled interface naturally integrates the quantum source, quantum memory, and quantum receiver in a single unit which exhibits great potential to develop highly compact and portable devices for quantum-enhanced remote sensing.