论文标题
探测磁性质量种群的量子纠缠：超越自旋挤压不平等
Probing quantum entanglement from magnetic-sublevels populations: beyond spin squeezing inequalities
论文作者
论文摘要
自旋挤压不平等（SSI）代表了探测几个少数原子集合中量子纠缠的主要工具，并基于集体自旋测量及其波动。然而，对于旋转$ j $原子和超速旋转气体的原子集合，许多实验可以在所有Zeeman sublevels中对种群进行成像，$ s = -j，-j+1，\ dots，j $，有可能揭示SSI未捕获的量子纠缠的更精细的特征。在这里，我们提出了一种系统的方法，该方法利用了Zeeman-ublevel种群测量，以构建新的纠缠标准，并说明了我们在Spin-1和Spin-2 Bose-2 Bose-Einstein冷凝物的基础状态下的方法。除了这些具体示例之外，我们的方法还允许人们以系统的方式推断出在$ d $级别量子系统集合中的任何给定的集体测量值的最佳排序纠缠见证人。
Spin squeezing inequalities (SSI) represent a major tool to probe quantum entanglement among a collection of few-level atoms, and are based on collective spin measurements and their fluctuations. Yet, for atomic ensembles of spin-$j$ atoms and ultracold spinor gases, many experiments can image the populations in all Zeeman sublevels $s=-j, -j+1, \dots, j$, potentially revealing finer features of quantum entanglement not captured by SSI. Here we present a systematic approach which exploits Zeeman-sublevel population measurements in order to construct novel entanglement criteria, and illustrate our approach on ground states of spin-1 and spin-2 Bose-Einstein condensates. Beyond these specific examples, our approach allows one to infer, in a systematic manner, the optimal permutationally-invariant entanglement witness for any given set of collective measurements in an ensemble of $d$-level quantum systems.
