论文标题
饱和一轴扭曲的量子cramér-rao与总自旋读数结合
Saturating the one-axis twisting quantum Cramér-Rao bound with a total spin readout
论文作者
论文摘要
我们表明，最低的量子cramér-rao在干涉中可以实现的界限与单轴扭曲的旋转相干状态可实现，这是通过一种协议的矩误差方法饱和，该协议的矩误差使用了一个轴扭曲，对单轴扭曲，一种呼吁，一个呼吁，一个呼叫，一个呼叫，一个时间转换为单轴的单轴扭曲，最终的旋转测量和最终的总测量（i.e.e.e.e.e.e.e.e.e.e.，tist Twist-nister-nist-twist-sixes）。首先表明，单轴扭曲的计量相图在渐近表征以单个量子Fisher信息值$ n（n+1）/2 $为单个扭曲的特征，然后构建具有矩误差方法以使该值饱和。类似地分析了有限范围的单轴扭曲的情况，并且在短程和远距离相互作用方案中都可以找到用于计量相图的简单功能形式。数值证据表明，Twist-untwist方案的有限范围类似物可以表现出一种矩误差的方法，该方法渐近地饱和，在所有相互作用时间内，在有限的单轴扭曲的旋转状态的干涉中，在干涉中可以实现的最低量子cramér-rao结合。
We show that the lowest quantum Cramér-Rao bound achievable in interferometry with a one-axis twisted spin coherent state is saturated by the asymptotic method of moments error of a protocol that uses one call to the one-axis twisting, one call to time-reversed one-axis twisting, and a final total spin measurement (i.e., a twist-untwist protocol). The result is derived by first showing that the metrological phase diagram for one-axis twisting is asymptotically characterized by a single quantum Fisher information value $N(N+1)/2$ for all times, then constructing a twist-untwist protocol having a method of moments error that saturates this value. The case of finite-range one-axis twisting is similarly analyzed, and a simple functional form for the metrological phase diagram is found in both the short-range and long-range interaction regimes. Numerical evidence suggests that the finite-range analogues of twist-untwist protocols can exhibit a method of moments error that asymptotically saturates the lowest quantum Cramér-Rao bound achievable in interferometry with finite-range one-axis twisted spin coherent states for all interaction times.
