Engineering a Flux-Dependent Mobility Edge in Disordered Zigzag Chains
Engineering a Flux-Dependent Mobility Edge in Disordered Zigzag Chains
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DOI：
10.1103/physrevx.8.031045
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发表时间：
2018-08-17
影响因子：
12.5
通讯作者：
Gadway, Bryce
中科院分区：
文献类型：
--
作者：
An, Fangzhao Alex;Meier, Eric J.;Gadway, Bryce
人们对人工规范场中带电粒子的实验研究很感兴趣。在这里，我们对人工规范场和无序的组合进行了第一次冷原子探索。利用基于参数耦合原子动量态的合成晶格技术，我们设计了具有可调均匀通量的锯齿形链。外加的磁通破坏了时间反转对称性，导致了类似的自旋-轨道耦合和自旋-动量锁定，我们通过初始为单一晶格位置的原子的手征动力学直接观察到了这一点。我们还引入了精确控制的无序，使我们能够探索无序和大的有效磁场之间的相互作用。在这个系统中，关联无序和受控的行内和行间隧道效应的结合自然支持与能量相关的局域化，与单粒子的迁移率边缘有关。我们测量了该系统的极值本征态、基态和最高激发态的局域化性质，并证明了存在依赖于磁通的迁移率边的明显证据。这些测量构成了低维系统中依赖能量的局域化的第一个直接证据，也是对人工规范场和工程无序的联合影响的第一次探索。此外，我们还提供了关联无序中低能和高能本征态的局域化跃迁相互作用的直接证据，这与多体迁移率边缘的存在有关。这个合成晶格系统中存在的强相互作用、受控无序和可调人工规范场的独特组合，应该能够使无数人探索有趣的相关输运现象。
There has been great interest in experimental studies of charged particles in artificial gauge fields. Here, we perform the first cold-atom explorations of the combination of artificial gauge fields and disorder. Using synthetic lattice techniques based on parametrically coupled atomic momentum states, we engineer zigzag chains with a tunable homogeneous flux. The breaking of time-reversal symmetry by the applied flux leads to analogs of spin-orbit coupling and spin-momentum locking, which we observe directly through the chiral dynamics of atoms initialized to single lattice sites. We additionally introduce precisely controlled disorder in the site-energy landscape, allowing us to explore the interplay of disorder and large effective magnetic fields. The combination of correlated disorder and controlled intrarow and interrow tunneling in this system naturally supports energy-dependent localization, relating to a single-particle mobility edge. We measure the localization properties of the extremal eigenstates of this system, the ground state and the most-excited state, and demonstrate clear evidence for a flux-dependent mobility edge. These measurements constitute the first direct evidence for energy-dependent localization in a lower-dimensional system, as well as the first explorations of the combined influence of artificial gauge fields and engineered disorder. Moreover, we provide direct evidence for interaction shifts of the localization transitions for both low-and high-energy eigenstates in correlated disorder, relating to the presence of a many-body mobility edge. The unique combination of strong interactions, controlled disorder, and tunable artificial gauge fields present in this synthetic lattice system should enable myriad explorations into intriguing correlated transport phenomena.