标题： 通过控制其准态子系统增强集体自旋的压缩 显示英文标题

标题： Enhanced squeezing of a collective spin via control of its qudit subsystems

摘要： 对量子比特进行幺正控制可以提高原子系综的集体自旋压缩。 使原子处于磁化强度具有大量子涨落的状态可以增强纠缠的法拉第相互作用。 由此产生的原子间纠缠增加可以转化为可用于计量的自旋压缩。 进一步的控制可以在不损害纠缠的情况下挤压原子的内部自旋，从而在集体压缩中提供一个整体乘法因子。 我们模拟了光学泵浦的影响，并研究了增强纠缠和去相干之间的权衡。 对于现实参数，我们看到了大约10 dB的改进。 显示英文摘要

摘要： Unitary control of qudits can improve the collective spin squeezing of an atomic ensemble. Preparing the atoms in a state with large quantum fluctuations in magnetization strengthens the entangling Faraday interaction. The resulting increase in interatomic entanglement can be converted into metrologically useful spin squeezing. Further control can squeeze the internal atomic spin without compromising entanglement, providing an overall multiplicative factor in the collective squeezing. We model the effects of optical pumping and study the tradeoffs between enhanced entanglement and decoherence. For realistic parameters we see improvements of ~10 dB.