量子多结构分组纠缠到达时间测量增强方法

根据量子测距原理，采用纠缠压缩态的量子脉冲代替经典的电磁脉冲可极大地提高到达时间的测量精度,但在实际的有损通道当中采用完全纠缠态量子脉冲的测量稳健性很差。相比之下，采用部分纠缠态可以有效地提高测量的稳健性，但其测量精度上会有所下降。鉴于上述的精度与稳健性之间的矛盾问题，提出了多结构分组纠缠的测量方法，并详细推导了纠缠度、量子传输效率与测量精度的之间的关系，得到了在特定量子通道传输效率条件下，纠缠分组结构、量子压缩光子数和最佳的量子纠缠度的选择方法，使得纠缠所能获得的测量精度增益达到最大。

Enhancement of the Time of Arrival Measuring by Utilizing Multi-Structured Grouped-Entangled Quantum Pulse

According to the principles of quantum ranging, the time of arrival (TOA) can be measured in a much higher accuracy by utilizing a quantum pulse which includes entangled-squeezed photons, than that by utilizing a classical electromagnetic pulse. However, the maximal entangled quantum pulse has a very poor robustness of measurement in a non-ideal transmission channel, since the loss of a single photon will make the TOAs of other photons to be totally useless. A partially entangled quantum pulse will have a better robustness of measurement, whereas its measurement accuracy would be reduced with the decrease of entanglement. In order to solve problem between the accuracy and the robustness of the measurement, a new structure of quantum entanglement utilizing grouped and squeezed photons is proposed in this paper. Also, the relationship between the degree of entanglement, quantum transmission efficiency, and the measurement precision is deduced in detail to analyze the performance of this kind of quantum entanglement structure. Finally, considering the specific quantum transmission efficiency, the maximum accuracy gain of the measurement is obtained through the selection of a proper quantum entangle structure, the number of photons to be squeezed and the optimal degree of entanglement.