量子计量学中的量子耗散噪声机制及其动力学控制研究

Quantum metrology is the study on making higher-precision measurement of physical parameters than the classically achievable one by exploiting quantum entanglement or quantum squeezing. As a ubiquitous phenomenon in quantum world, decoherence induced by different quantum noises exerts a constraint on the practical realization of quantum metrology schemes. It is one of the crucial issues in this field to explore the detrimental influences caused by the decoherence on quantum metrology and its efficient suppression protocols. Different from the widely studied Markovian dephasing noise in the literature, we will study the effect of the dissipative noise on the quantum metrology schemes based on Mach-Zehnder interferometer and Ramsey spectroscopy. It is our main point to reveal the constructive role played by the non-Markovian effect in improving the measurement precision of the two metrology schemes under such noise. We will also study the protocol to suppress the detrimental influences by use of a periodic driving strategy. In the framework of the Floquet theory, we will establish the relationship between the characters of the quasi-energy spectrum under differerent driving conditions and the obtained metrology precision. Then we can find the necessary driving condition to obtained the high-precision measurement. By the studies in this project, we expect to supply the mechanisms of dissipative noise on quantum metrology and the optimal physical condition to achieve the precision that surpasses the shot-noise limit or even recovers the Heisenberg limit.

量子计量学是利用微观多体系统的量子纠缠或压缩资源来实现超越经典物理允许精度的测量科学，但其实现受到了微观世界普遍存在的各类噪声所导致的退相干的束缚，探索退相干对量子计量的破坏性影响并寻求有效的抑制方案是该领域研究的核心。不同于普遍研究的Markovian近似与去相位噪声，本项目拟系统地研究耗散噪声对基于Mach-Zehnder干涉仪和Ramsey干涉仪的两种计量方案精度的影响，揭示该耗散噪声的non-Markovian效应对利用这两种方案进行频率和磁场等计量的精度提高的建设性作用；同时我们还将探索周期性驱动方案对耗散噪声导致的计量破环性作用的抑制作用，利用Floquet理论建立不同驱动条件下系统准能谱特性与计量精度的对应关系，寻找获得耗散噪声下最佳计量精度的驱动条件，以此来对退相干效应进行抑制。通过研究，我们期待揭示耗散噪声下超越散粒噪声极限甚至是恢复Heisenberg极限的物理条件。

本项目围绕量子计量学中退相干控制与凝聚态物理学中新型量子和拓扑物态的量子调控等关键问题，利用束缚态理论建立了周期驱动与开放两类量子科技中常见系统统一的物理框架。揭示了开放系统和环境组成的复合系统能谱束缚态对开放系统退相干的决定机制，进而提出了退相干控制的库工程策略，并发现该策略在稳定量子自旋压缩的可集成化制备、噪声量子计量的理想精度恢复、低温量子热力仪、量子光学陀螺仪、量子表面等离/激子激元的耗散抑制和量子速度极限等量子科技应用中的支配作用。揭示了周期性驱动系统的Floquet准能谱束缚态所刻画的非平衡量子/拓扑物态，进而提出量子/拓扑物态调控的Floquet工程策略，其将量子材料中的“能带工程”扩展至非平衡系统，并发现该策略在抑制噪声量子计量的止步定理、量子电池老化和人工合成以奇异非厄米拓扑绝缘体和混合阶Weyl半金属等为代表的新颖拓扑物态中的优势。发表学术论文19篇，其中PRL2篇，快讯和快报5篇。项目负责人入选国家万人计划青年拔尖人才、中央军委科技委国防科技创新特区专家、中科院青年创新促进会特邀会员和甘肃省领军人才、中国物理学会量子光学专业委员会委员；项目组成员入选2022年度博士后创新人才支持计划。