Dynamics of spin-orbit-coupled cold atomic gases in a Floquet lattice with an impurity
Dynamics of spin-orbit-coupled cold atomic gases in a Floquet lattice with an impurity
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含有杂质的 Floquet 晶格中自旋轨道耦合冷原子气体的动力学
DOI：
10.1088/1361-6455/ab0e5d
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发表时间：
2019
期刊：
影响因子：
--
通讯作者：
Hu Qianglin
中科院分区：
文献类型：
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作者：
Luo Xiaobing;Yang Baiyuan;Cui Jin;Guo Yu;Li Lei;Hu Qianglin
本文研究了含杂质的周期调制光晶格中自旋轨道耦合单原子的量子隧穿。结果发现，即使杂质势与驱动场远离共振，动力学局域化也发生在准能谱的坍缩点处。同时，在自旋不变和杂质位布居可忽略的情况下，在杂质的两个最近邻位之间出现了两种超出预期的局域二阶隧穿过程.虽然这两种类型的隧穿行为似乎是相同的，但它们被认为涉及两种不同的机制：一种是与自旋无关的隧穿过程，而另一种是与自旋相关的隧穿过程。这两种类型的二阶过程可以通过调谐杂质势使其与驱动场共振来识别。在Floquet图像中，具有局域杂质的系统在塌缩点附近发展出避免准能交叉的精细结构，这对于理解所谓的二阶隧穿动力学至关重要。这些结果在有效三位点模型和多时间尺度渐近微扰方法的基础上得到了解析证实，并可用于实际实验中自旋相关量子输运的工程设计.
In this work, we have studied the quantum tunneling of a single spin–orbit-coupled atom held in a periodically modulated optical lattice with an impurity. As a result we find that the dynamical localization takes place globally at the collapse points of quasienergy spectrum, even when the impurity potential is far off-resonant with the driving field. Meanwhile, two types of local second-order tunneling processes appear beyond expectation between the two nearest-neighbor sites of the impurity, with the spin unchanged and with the impurity site population negligible. Though tunneling behaviors of the two types seem to be the same, they are believed to involve two distinct mechanisms: one is related to spin-independent process, while the other is to spin-dependent tunneling process. The two types of second-order processes can be identified by means of resonant tunneling with or without spin flipping by tuning the impurity potential to be in resonance with the driving field. In the Floquet picture, the system with the localized impurity develops a fine structure of avoided crossings of quasienergies near the collapse point, which is crucial to understand the so-called second-order tunneling dynamics. These results are confirmed analytically on the basis of effective three-site model and multiple-time-scale asymptotic perturbative method, and may be exploited for engineering the spin-dependent quantum transport in realistic experiments.