量子精密测量中的量子不和谐解释

量子不和谐决定了量子态的干涉功率

Quantum discord determines the interferometric power of quantum states

量子精密测量利用量子力学定律来提高估计技术相关参数（例如相位、频率或磁场）的精度。探测器状态通常根据其参数正在被估计的特定动态来定制。在这里，我们考虑一个新的框架，量子估计进行干涉配置，使用二分探针状态时，只有生成的哈密顿量的频谱是已知的。我们引入了一个图的计划，给出了最坏情况下的精度在所有合适的哈密顿量，并证明了它的金额正好是一个可计算的测量输入探针的不和谐型量子相关。我们补充我们的理论结果与计量实验，实现了在一个高度可控的室温核磁共振设置，这提供了一个概念验证的演示的有用性不和谐的传感应用。不一致的探针，以保证非零精度的估计过程中，不同的生成哈密顿，而经典相关的探针是无法完成的估计在最坏的情况下设置。这项工作为一般量子相关性建立了严格而直接的操作解释，揭示了它们在量子技术中的潜力。

Intrinsic relationships of Quantum Resource Theories and their roles in Quantum Metrology

Quantum resource theories allow us to quantify a useful quantum phenomenon, to develop new protocols for its detection and determine the exact processes that maximize its use for practical tasks. These theories aim at transforming physical phenomena, such as entanglement and quantum coherence, into useful properties for the execution of concrete tasks related to quantum information. In this thesis, we focus on the resource theories of entanglement, discord-like quantum correlations, and quantum coherence, the most intriguing quantum phenomena exploited so far in quantum information theory. We …

Interpreting quantum coherence through a quantum measurement process

Recently, there has been a renewed interest in the quantification of coherence or other coherence-like concepts within the framework of quantum resource theory. However, rigorously defined or not, the notion of coherence or decoherence has already been used by the community for decades since the advent of quantum theory. Intuitively, the definitions of coherence and decoherence should be the two sides of the same coin. Therefore, a natural question is raised: how can the conventional decoherence processes, such as the von Neumann-Lüders (projective) measurement postulation or partially dephasi…

量子同步与耗散量子传感

Quantum Synchronization and Dissipative Quantum Sensing

该研究从量子计量学视角出发，将量子自激振荡器视为耗散量子传感器，提出以量子Fisher信息作为量子同步的通用度量，并拓展至多体多驱动场景，揭示了二者的关联，为量子同步的技术应用提供了新方向。

A comparative study of local quantum Fisher information and local quantum uncertainty in Heisenberg $XY$ model

Recently, it has been shown that the quantum Fisher information via local observables and via local measurements (i.e., local quantum Fisher information (LQFI)) is a central concept in quantum estimation and quantum metrology and captures the quantumness of correlations in the multi-component quantum system [S. Kim et al., Phys. Rev. A. 97, 032326 (2018)]. This new discord-like measure is very similar to the quantum correlations measure called local quantum uncertainty (LQU). In the present study, we have revealed that LQU is bounded by LQFI in the phase estimation protocol. Also, a comparativ…

利用局域量子不确定性刻画非经典关联

Characterizing Nonclassical Correlations via Local Quantum Uncertainty

量子力学预言，不相容的可观测量的测量具有最小的不确定性，该不确定性与测量设备的技术缺陷或系统状态的不完整知识无关。似乎还没有什么能阻止一个单一的物理量，比如一个自旋分量，被任意精确地测量。在这里，我们表明，一个单一的可观察的内在量子不确定性是不可避免的，在许多物理情况。当揭示在一个二分系统的局部观测，这种不确定性定义了一个真正的措施，非经典相关性的整个类。对于2 × d系统的情况，我们发现定义了一个唯一的测度，我们以封闭形式评估。然后，我们讨论的作用，这些相关性，这是“不和谐”的类型，可以发挥在量子精密测量的背景下。我们特别表明，在一个二分混合探针状态中存在的不和谐的量保证了最小的精度，量化的量子费舍尔信息，在最佳相位估计协议。

通过幺正分束器产生的Bell相干态叠加中的干涉相位估计与量子资源动力学

Interferometric phase estimation and quantum resources dynamics in Bell coherent-states superpositions generated via a unitary beam splitter

本研究提出通过分束器输入Glauber相干态和真空态产生Bell相干态叠加的方案，推导多种量子资源量化指标的解析形式，提出弱测量诱导的局部量子不确定性概念，揭示干涉相位估计灵敏度与测量强度的关联及弱测量的量子特性捕获规律。

Black-box estimation of expanding parameter for de Sitter universe

We study the black-box parameter estimation of expanding parameters and the dynamics of Gaussian interferometric power for the de Sitter space. We find that the state between separated open charts can be employed as probe state for the black-box quantum metrology. This is nontrivial because the open charts are causally disconnected and classical information can not be exchanged between them according to the general relativity. It is shown that the mass of the scalar field remarkably affects the accuracy of the black-box parameter estimation in the de Sitter space, which is quite different from…