Fig. 1. Statistical distribution of photon numbers. (a) Thermal distribution; (b) Coherent distribution; (c) Mixed distribution

Fig. 2. Statistical distribution of coherent and squeezed states. (a) r=0.5, ; (b) r=0.2, 相干态与压缩态的统计分布。(a) r=0.5, ；(b) r=0.2,

Fig. 3. Detection probability of photon-counting lidar under different thresholds

Fig. 4. False alarm probability of photon-counting lidar under different thresholds

Fig. 5. SNR ratio of quantum threshold detection and light intensity detection

Fig. 6. SNR ratio of quantum-enhanced detection and light intensity detection. (a) r=0.2; (b) r=1

Fig. 7. Simulation results comparing of intensity detection and quantum threshold detection