论文标题
非马克维亚在空间相关的量子噪声下的频率估计：恢复超级精度缩放
Frequency estimation under non-Markovian spatially correlated quantum noise: Restoring superclassical precision scaling
论文作者
论文摘要
我们研究在存在时空相关的非古典噪声的情况下，可以通过纠缠增强的拉姆西干涉法实现的估计精度。我们的分析依赖于在一般零均值的高斯固定式dephasing下的量子探针降低的密度矩阵的精确表达，该量子是通过累积扩张技术建立的，并且在非马克维亚开放动力学的背景下可能具有独立的利益。通过继续并扩大我们以前的工作[Beaudoin等，Phys。 Rev. A 98，020102（r）（2018）]，我们分析了量子探针及其环境之间非集合耦合方案的影响，重点是两个限制场景，其中耦合只能占用两个或可能需要两个或可能的值的连续性。在热环境中自旋 - 玻璃孔降低噪声的范式情况下，我们发现，只要在噪声相关性负数的情况下对足够的配置进行采样，则可以平均抑制空间相关性的效果，只要对探针的位置进行随机抑制。结果，对于初始纠缠状态，包括实验可访问的一轴自旋式状态，超级精度缩放是渐近恢复的。
We study the estimation precision attainable by entanglement-enhanced Ramsey interferometry in the presence of spatiotemporally correlated non-classical noise. Our analysis relies on an exact expression of the reduced density matrix of the qubit probes under general zero-mean Gaussian stationary dephasing, which is established through cumulant-expansion techniques and may be of independent interest in the context of non-Markovian open dynamics. By continuing and expanding our previous work [Beaudoin et al., Phys. Rev. A 98, 020102(R) (2018)], we analyze the effects of a non-collective coupling regime between the qubit probes and their environment, focusing on two limiting scenarios where the couplings may take only two or a continuum of possible values. In the paradigmatic case of spin-boson dephasing noise from a thermal environment, we find that it is possible to suppress, on average, the effect of spatial correlations by randomizing the location of the probes, as long as enough configurations are sampled where noise correlations are negative. As a result, superclassical precision scaling is asymptotically restored for initial entangled states, including experimentally accessible one-axis spin-squeezed states.
