Coherent Two-Photon Atmospheric Lidar Based on Up-Conversion Quantum Erasure

The Hong-Ou-Mandel (HOM) effect, also called two-photon interference, which is pivotal in quantum information processing, serves as the foundation for our coherent two-photon wind detection method, achieving time-frequency discrimination. Our method capitalizes on the complete erasure of phase and color distinctions with up-conversion detectors, allowing for the observation of HOM interference among independently sourced photons without necessitating delay tuning or active synchronization. The integration of quantum erasure enhances the bandwidth in both space-time and frequency domains, paving the way for ultrafast, continuous velocity detection up to tens of km/s. The demonstration uses just 14% pulse energy of previous levels, enabling a wind detection range up to 16 km, marking a quantum leap in remote sensing capabilities.