论文标题
用集体旋转预测的超翼型的确定性准备
Deterministic preparation of supersinglets with collective spin projections
论文作者
论文摘要
我们介绍了一种生成超翼链的程序，即角动量单线状态的多部分概括。超级单元定义为由$ n $ spin- $ j $颗粒组成的总旋转零状态。它们是高度纠缠的，并且在任何方向上具有零自旋方差，因此对于量子计量学有可能有用。我们的方案基于投影测量值，该测量值测量整个旋转合奏的集体自旋。局部统一旋转有条件地应用于测量结果，例如最大化在随后的测量中获得零旋转的概率。在$ z $ - 和$ x $ -BASI中重复该序列，直到获得向超词状态的收敛为止。无论初始状态如何，我们的序列都起作用，不需要选择后。由于使用了强射测量，因此获得了非常快速的旋转方差的快速收敛。我们讨论了一个示例使用原子集合中的量子非安装测量值的实现，并执行数值模拟以证明该过程。
We introduce a procedure to generate supersinglets, the multipartite generalization of angular momentum singlet states. A supersinglet is defined as a total spin zero state consisting of $ N $ spin-$ j $ particles. They are highly entangled and have zero spin variance in any direction, and as such are potentially useful for quantum metrology. Our scheme is based on projective measurements that measure the collective spin of the whole spin ensemble. A local unitary rotation is applied conditionally on the measurement outcome, such as to maximize the probability of obtaining spin zero on the subsequent measurement. The sequence is repeated in the $ z $- and $ x $-basis until convergence is obtained towards the supersinglet state. Our sequence works regardless of the initial state, and no postselection is required. Due to the use of strong projective measurements, very fast convergence towards zero spin variance is obtained. We discuss an example implementation using quantum nondemolition measurements in atomic ensembles, and perform numerical simulations to demonstrate the procedure.
