Demonstration of quantum-enhanced rangefinding robust against classical jamming
In this paper we demonstrate operation of a quantum-enhanced lidar based on a continuously pumped photon pair source combined with simple detection in regimes with over 5 orders of magnitude separation between signal and background levels and target reflectivity down to -52 dB. We characterise the performance of our detector using a log-likelihood analysis framework, and crucially demonstrate the robustness of our system to fast and slow classical jamming, introducing a new protocol to implement dynamic background tracking to eliminate the impact of slow background changes whilst maintaining immunity to high frequency fluctuations. Finally, we extend this system to the regime of rangefinding in the presence of classical jamming to locate a target with an 11 cm spatial resolution limited only by the detector jitter. These results demonstrate the advantage of exploiting quantum correlations for lidar applications, providing a clear route to implementation of this system in real-world scenarios.