Covert Quantum Target Sensing

We study the Quantum Target Ranging task in the context of multi-hypothesis testing and its application to real-world LiDAR systems. We find the theoretical bounds and the advantages of quantum ranging in presence of background considering time-of-flight measurements, the operational mode of most LiDAR systems [1]. Moreover, we focus on the covert scenario, in which the sensing is performed while avoiding detection from an adversary. Interestingly, we discover that against a technologically evolved adversary, covertness is only possible with a quantum probe state constrained by a low mean number of photons, while classical transmitter fails to ensure covertness [2]. We realize an experimental demonstration of the protocol exploiting commercial sources of photon pairs at telecom wavelength and superconducting nanowire single photon detectors in a tree configuration. We demonstrate a large quantum advantage with respect to a conventional approach that uses short-pulsed laser at the same power.

Our results represent a new perspective on optical quantum sensing and provide strong motivation for the development of quantum LiDAR.

Acknowledgements: This project has received funding from the European Defence Fund (EDF) under grant agreement 101103417 EDF-2021-DIS-RDIS-ADEQUADE. Funded by the European Union. Views and opinions expressed are however those of the author(s) only and do not necessarily reflect those of the European Union or the European Commission. Neither the European Union nor the granting authority can be held responsible for them.