发表机构
Stevens Institute of Technology（史蒂文斯理工学院）
机构由 AI 辅助整理，请以论文原文为准。AI 中文总结
本研究探讨开放系统中色散耦合计量，发现探针选择、环境记忆及测量方式共同影响灵敏度，并找到接近量子极限的固定可观测量。
AI 中文摘要
我们研究了在腔量子比特系统中，光子损失和环境记忆如何影响用于估计色散耦合强度的探针选择与测量灵敏度。利用密度算子和量子态扩散方法，我们考察了在马尔可夫和非马尔可夫 regime 中，具有代表性的可分离和纠缠初始态的量子 Fisher 信息。结果表明，仅凭封闭系统的生成元方差并不能决定开放系统的性能。参数敏感相干性的存活以及环境记忆的影响也起着重要作用。在所考察的单光子制备中，可分离探针可以胜过所考虑的纠缠族。在相同平均光子数下，对选定的相干态和压缩真空态制备的比较进一步说明了光子数统计和量子比特制备如何影响灵敏度。对于所研究的参数，有限的环境记忆可以增强并延长灵敏度，并为马尔可夫 QFI 为零的探针产生非零的 QFI。我们还数值确定了一个固定的厄米可观测量，其误差传播不确定性在马尔可夫 regime 中规定的耦合区间内接近量子 Cramér-Rao 界。这些发现阐明了在色散量子计量学中，探针制备、环境动力学和测量选择之间的相互作用。
英文摘要
We investigate how photon loss and environmental memory affect probe selection and measurement sensitivity for estimating the dispersive coupling strength in a cavity qubit system. Using density operator and quantum state diffusion approaches, we examine the quantum Fisher information for representative separable and entangled initial states in Markovian and non Markovian regimes. The results show that closed system generator variance alone does not determine open system performance. The survival of parameter sensitive coherences and the influence of environmental memory also play important roles. Within the single photon preparations examined, a separable probe can outperform the entangled family considered. Comparisons of selected coherent and squeezed vacuum preparations at equal mean photon number further illustrate how photon number statistics and qubit preparation affect sensitivity. For the parameters studied, finite environmental memory can enhance and prolong sensitivity and yield nonzero QFI for a probe whose Markovian QFI vanishes. We also numerically identify a fixed Hermitian observable whose error propagation uncertainty remains close to the quantum Cramer Rao bound over a prescribed coupling interval in the Markovian regime. These findings clarify the interplay between probe preparation, environmental dynamics, and measurement choice in dispersive quantum metrology.
Comments16 pages, 8 figures
