Wang Qiang, Hao Lili, Zhang Yong, Xu Lu, Yang Chenghua, Yang Xu, Zhao Yuan
Opt Express. 2016 Mar 7;24(5):5045-5056. doi: 10.1364/OE.24.005045.
We investigate the performance of the super-resolving quantum lidar with the entangled coherent states of light in the presence of loss and noise, especially in the noisy case. An exact analytical expression of the output signal has been derived with the binary-outcome photon counting measurements. Numerical results show that the resolution of our scheme with parity detection is √N (N) times enhanced relative to that of the coherent-state strategy with the same (intensity) detection in the lossless and noiseless cases. The influences of phase diffusion on resolution and sensitivity have been analyzed and discussed. It is found that the super-resolution emerges in the whole diffusion rate regions, whereas the super-sensitivity just exists in the high and low diffusion rate regimes. Comparisons are made with the well known N00N states, the results show that the entangled coherent states performs better resolution and sensitivity than those of the N00N scheme in the whole diffusion regimes. In addition, the effects of photon loss on resolution and sensitivity have also been studied. The phase sensitivity can beat the shot noise limit and the resolution is much better than the Rayleigh diffraction limit in the whole loss regions. Finally, the zero-nonzero photon counting measurement gives much worse sensitivity than that of the parity detection, which is just opposite from the case as demonstrated in a recent coherent-light Mach-Zehnder experiment.
我们研究了在存在损耗和噪声，特别是在噪声情况下，具有纠缠相干态光的超分辨量子激光雷达的性能。通过二值结果光子计数测量，推导得到了输出信号的精确解析表达式。数值结果表明，在无损和无噪声情况下，我们采用奇偶性检测方案的分辨率相对于采用相同（强度）检测的相干态策略提高了√N（N）倍。分析并讨论了相位扩散对分辨率和灵敏度的影响。结果发现，超分辨率出现在整个扩散速率区域，而超灵敏度仅存在于高扩散速率和低扩散速率区域。与著名的N00N态进行了比较，结果表明，在整个扩散区域，纠缠相干态的分辨率和灵敏度均优于N00N方案。此外，还研究了光子损耗对分辨率和灵敏度的影响。在整个损耗区域，相位灵敏度可以突破散粒噪声极限，分辨率远优于瑞利衍射极限。最后，零非零光子计数测量的灵敏度远低于奇偶性检测，这与最近的相干光马赫 - 曾德尔实验的情况正好相反。
