Internal Spin Control, Squeezing and Decoherence in Ensembles of Alkali Atomic Spins
Internal Spin Control, Squeezing and Decoherence in Ensembles of Alkali Atomic Spins
复制标题
碱原子自旋系综中的内自旋控制、挤压和退相干
DOI：
--
复制
发表时间：
2014
期刊：
影响因子：
--
通讯作者：
Leigh M. Norris
中科院分区：
文献类型：
--
作者：
Leigh M. Norris
本文研究了大系综中具有超精细自旋f的碱金属冷原子与光场相互作用系统的自旋压缩、纠缠和退相干。将每个原子的状态限制为嵌入2f+1维超精细自旋的qutrit，使我们能够有效地模拟系综的相干和耗散动力学。这种形式主义也使我们能够探索局部控制对原子内部超精细自旋的影响。使用这种控制的状态准备增加了f>1/2的原子-光界面的纠缠功率。随后对内部自旋的控制将纠缠转化为计量相关的自旋压缩。在量子非破坏测量压缩的情况下，我们采用数值搜索，以找到在退相干的存在下最大化自旋压缩的状态准备。我们的系统的耗散动力学包括由于自发辐射的光泵浦。虽然大多数作品忽略光泵浦或对待它唯象，我们采用了一个主方程来自第一原理。本文的工作被推广到原子系综与非均匀傍轴探针相互作用的情形。对系综和探针的几何结构进行了优化，以最大限度地提高空间模式匹配和自旋压缩。
This dissertation studies spin squeezing, entanglement and decoherence in large ensembles of cold, trapped alkali atoms with hyperfine spin f interacting with optical fields. Restricting the state of each atom to a qutrit embedded in the 2f+1 dimensional hyperfine spin enables us to efficiently model the coherent and dissipative dynamics of the ensemble. This formalism also allows us to explore the effects of local control on the internal hyperfine spins of the atoms. State preparation using such control increases the entangling power of the atom-light interface for f>1/2. Subsequent control of the internal spins converts entanglement into metrologically relevant spin squeezing. In the case of squeezing by quantum nondemolition measurement, we employ a numerical search to find state preparations that maximize spin squeezing in the presence of decoherence. Dissipative dynamics on our system include optical pumping due to spontaneous emission. While most works ignore optical pumping or treat it phenomenologically, we employ a master equation derived from first principles. This work is extended to the case of an atomic ensemble interacting with a non-homogeneous paraxial probe. The geometries of the ensemble and the probe are optimized to maximize both spatial mode matching and spin squeezing.