发表机构
School of Science, Guiyang University（贵阳大学理学院）
机构由 AI 辅助整理，请以论文原文为准。AI 中文总结
研究宇宙弦存在时对两能级可极化原子动力学的影响（类似反射边界），通过对单个探测原子进行N次测量来估计量子边界效应，给出最优初始态、测量及缩短探测时间等提高精度的方法。
AI 中文摘要
宇宙弦的存在改变真空涨落，使两能级可极化原子的演化依赖位置。这种改变对原子动力学产生类似反射边界的效应。我们表明，通过对单个探测原子进行一系列N次测量可估计这些量子边界效应。对于固定的总探测时间，通过将每个探测器制备在其最优初始状态、执行相应的最优测量并缩短每个探测器的探测时间来达到精度极限。最优测量由探测器的初始状态唯一确定，并且原子初始处于激发态时获得的精度极限比等权重叠加态高四倍。随着原子与边界或原子与弦的间距增加，估计精度呈现阻尼振荡行为。在边界情况下，平行于反射边界的极化总是最优的，而在宇宙弦时空中，最优极化取决于原子与弦的间距和亏角。对于小亏角和足够大的间距，沿宇宙弦方向的极化变得不如其他极化方向。
英文摘要
The presence of a cosmic string modifies vacuum fluctuations, making the evolution of a two-level polarizable atom position-dependent. Such modifications produce effects on the atomic dynamics analogous to those induced by a reflecting boundary. We show that these quantum boundary effects can be estimated by performing a sequence of $N$ measurements on a single probe atom. For a fixed total probe time, the precision limit is attained by preparing each probe in its optimal initial state, performing the corresponding optimal measurement, and shortening the probe time of each probe. The optimal measurement is uniquely determined by the probe's initial state, and the precision limit obtained with the atom initially in the excited state is four times higher than that for an equal-weight superposition state. The estimation precision displays damped oscillatory behavior as the atom-boundary or atom-string separation increases. In the boundary case, the optimal polarization is always parallel to that boundary. In cosmic-string spacetime, by contrast, the optimal polarization is along the azimuthal direction around the string. The relative advantage of the other polarization directions depends on both the atom-string separation and the deficit angle. For small deficit angles and sufficiently large separations, radial polarization perpendicular to the string becomes less favorable than the other directions.
