CAREER: Covert Quantum Sensing

量子信息处理为传感系统的精度提供了数量级的提高。同时，许多实际的传感场景需要主动探测传输和隐蔽（即低概率的探测/拦截——LPD/LPI）操作，以防止对手探测到探测尝试。该项目侧重于量化量子信息处理提供的隐蔽测距和反射传感的安全性和准确性的基本改进，以及用于实现这些增益的系统和算法。除了国防方面的明确应用外，该项目还产生了实现下一代隐私架构所需的技术，以及对传感和估计数学的广泛见解。此外，研究团队指导参与该项目的研究生和本科生，并通过吸引来自代表性不足群体的本科生，开展一项全面的教育计划，专注于发展国家的量子劳动力。防止传输被对手发现需要使用非常低功率的信号。尽管这些信号在隐蔽通信中的应用是信息论研究的一个活跃领域，但它们在传感应用中使用的基本限制几乎没有被探索过。此外，虽然量子方法已被证明可以显著提高传感精度，但这些增益似乎只有在信噪比低、噪声水平高的情况下才会显现。这种状态在标准传感系统中是非常不寻常的；然而，这是隐蔽传感的一种自然状态。因此，本项目采用量子视角进行隐蔽传感。它旨在确定隐蔽测距和反射传感的基本极限，以确保对抗仅受物理定律约束的对手。这个假设产生了数学上可证明的隐蔽性，可以抵御最强大的对手。从量子资源如纠缠，光的量子态和联合探测接收器的性能增强进行了探索。此外，发射机和接收机的结构和算法寻求实现这些改进。该奖项反映了美国国家科学基金会的法定使命，并通过使用基金会的知识价值和更广泛的影响审查标准进行评估，被认为值得支持。

Quantum information processing offers orders-of-magnitude enhancements in the precision of sensing systems. At the same time, many practical sensing scenarios require both active-probe transmission and covert (i.e., low probability of detection/intercept -- LPD/LPI) operation to prevent an adversary from detecting the probing attempt. This project focuses on quantifying the fundamental improvements to the security and accuracy of covert ranging and reflectance sensing offered by quantum information processing, as well as the systems and algorithms applied to achieve these gains. Aside from the clear applications for national defense, this project yields the technology necessary to implement next-generation privacy architectures, as well as broad insights into the mathematics of sensing and estimation. Additionally, the research team mentors graduate and undergraduate students involved in this project, and conducts a comprehensive educational program focused on growing the nation’s quantum workforce by engaging the undergraduate students from underrepresented groups.Preventing transmissions from being detected by the adversary requires employing very-low-power signals. Even though the application of such signals to covert communications is an active area of research in information theory, the fundamental limits of their use in sensing applications has barely been explored. Furthermore, while quantum methodology has been proven to yield significant improvements in sensing accuracy, these gains seem to be manifest only when SNR is low and noise level is high. This regime is highly unusual in standard sensing systems; however, it is a natural state for covert sensing. Thus, this project takes on the quantum perspective to covert sensing. It looks to determine the fundamental limits of covert ranging and reflectance sensing, secure against the adversary who is only subject to the laws of physics. This assumption yields mathematically-provable covertness against the most powerful adversary possible. Performance enhancements from quantum resources such as entanglement, quantum states of light, and joint-detection receivers are explored. Furthermore, transmitter and receiver structures and algorithms are sought to achieve these improvements.This award reflects NSF's statutory mission and has been deemed worthy of support through evaluation using the Foundation's intellectual merit and broader impacts review criteria.