基于可预知单光子源的反欺骗量子激光雷达的实验研究

Among the several types of quantum lidar schemes nowadays, quantum secured lidar is one of the few examples that will be most likely put into practical use in the near future. By exploiting quantum non-cloning theorem, quantum secured lidar grants the detection system immunity against intercept-resend jamming attacks, which will provide great advantages on the real battlefield. At present, proof-of-principle studies of this technique have been carried out with quantum secured lidar system based on weak coherent lasers. However, it will be of little practical use unless several key issues are addressed, including preventing photon number splitting attack and imaging in low-light-level conditions. In this project we propose that by making use of the heralded single photon source and low-light-level imaging techniques such as first photon imaging, the above two difficulties can be both overcome. To demonstrate this, we will experimentally compare quantum secured lidar systems based on weak coherent lasers and heralded single photon source so as to verify the latter’s immunity against photon number splitting attack. On the other hand, we aim to achieve high quality imaging in quantum secured lidar system. Specifically we will investigate suppression of background noise through employing heralded single photon source and suppression of poisson noise through low-light-level imaging techniques, respectively. The study of this project will provide a solid foundation for practical applications of quantum secured lidar under real circumstances.

现今几类量子激光雷达方案中，反欺骗量子激光雷达有望最先获得实际应用。利用量子态不可克隆定理，反欺骗量子激光雷达使探测系统免遭截获-重发的干扰攻击，因而可在实际战场上提供巨大优势。目前人们在基于弱相干激光光源的系统中对反欺骗量子激光雷达技术进行了原理验证研究。不过几个尚未解决的重要问题大大降低了该技术的实用性，包括对光子数分束攻击的防范和低照度条件下的成像。本项目中我们提出通过引入可预知单光子源和第一光子成像等低照度成像技术可以克服上述两个困难。为了证明这一点，我们将实验上对比基于弱相干激光光源和基于可预知单光子源的反欺骗量子激光雷达系统，验证后者对光子数分束攻击的防御能力。另一方面，我们将研究反欺骗量子激光雷达系统中的高质量成像。具体而言，我们将分别研究可预知单光子源对背景光噪声的抑制和低照度成像技术对泊松噪声的抑制。本项目的研究将为反欺骗量子激光雷达在现实环境下的实际应用提供坚实的基础。

我们从推动反欺骗量子激光雷达的实用化出发，对多重编码的反欺骗量子激光雷达以及弱值放大测量技术进行了研究。我们提出了多重编码反欺骗量子激光雷达的概念，即在一套雷达系统中利用不同的光子自由度对成像过程进行安全测试。由于基于不同光子自由度的各个安全测试很难同时失效，多重编码的反欺骗量子雷达相对于单一编码可以更有效地抵御截获-重发攻击。为了予以验证，我们提出了一套双重编码的反欺骗量子雷达方案，同时兼容了偏振编码和相位编码。另一方面，我们发展了一种基于Mach-Zender型干涉仪的弱值放大偏转角测量方法。由于该方案中的弱值为纯虚数，所测偏转角有可能获得两到三个数量级的放大。该方法可直接测量入射光偏转角度，因此非常适用于激光测姿应用，如激光信标跟踪等。后续，我们希望探讨弱测量技术在量子激光雷达中的应用可能性。截至2020年4月，项目资助申请专利一项，两篇论文正在准备整理发表。项目培养硕士生1名。