Dipartimento di Fisica, Università di Napoli Federico II, Complesso Universitario di Monte Sant'Angelo, Via Cintia, Napoli 80126, Italy.
ICFO-Institut de Ciencies Fotoniques, The Barcelona Institute of Science and Technology, Av. Carl Friedrich Gauss 3, Castelldefels 08860, Spain.
Nat Commun. 2017 Jun 1;8:15516. doi: 10.1038/ncomms15516.
Topological insulators are fascinating states of matter exhibiting protected edge states and robust quantized features in their bulk. Here we propose and validate experimentally a method to detect topological properties in the bulk of one-dimensional chiral systems. We first introduce the mean chiral displacement, an observable that rapidly approaches a value proportional to the Zak phase during the free evolution of the system. Then we measure the Zak phase in a photonic quantum walk of twisted photons, by observing the mean chiral displacement in its bulk. Next, we measure the Zak phase in an alternative, inequivalent timeframe and combine the two windings to characterize the full phase diagram of this Floquet system. Finally, we prove the robustness of the measure by introducing dynamical disorder in the system. This detection method is extremely general and readily applicable to all present one-dimensional platforms simulating static or Floquet chiral systems.
拓扑绝缘体是一类引人入胜的物质状态，其体内具有受保护的边缘态和稳健的量子化特征。在这里，我们提出并实验验证了一种在一维手征系统体内探测拓扑性质的方法。我们首先引入平均手征位移，这是一个可观测量，在系统的自由演化过程中，它迅速趋近于一个与 Zak 相位成正比的值。然后，我们通过在其体内测量平均手征位移，来测量光子量子漫步中的 Zak 相位。接下来，我们在一个替代的、不等价的时间框架内测量 Zak 相位，并将两个缠绕结合起来，以描绘这个 Floquet 系统的完整相图。最后，我们通过在系统中引入动态无序来证明该测量的稳健性。这种探测方法非常通用，可轻易应用于所有现有的模拟静态或 Floquet 手征系统的一维平台。
