Keil Robert, Poli Charles, Heinrich Matthias, Arkinstall Jake, Weihs Gregor, Schomerus Henning, Szameit Alexander
Institut für Experimentalphysik, Universität Innsbruck, Technikerstrasse 25, 6020 Innsbruck, Austria.
Department of Physics, Lancaster University, Lancaster LA1 4YB, United Kingdom.
Phys Rev Lett. 2016 May 27;116(21):213901. doi: 10.1103/PhysRevLett.116.213901.
We present a method of locally inverting the sign of the coupling term in tight-binding systems, by means of inserting a judiciously designed ancillary site and eigenmode matching of the resulting vertex triplet. Our technique can be universally applied to all lattice configurations, as long as the individual sites can be detuned. We experimentally verify this method in laser-written photonic lattices and confirm both the magnitude and the sign of the coupling by interferometric measurements. Based on these findings, we demonstrate how such universal sign-flipped coupling links can be embedded into extended lattice structures to impose a Z_{2}-gauge transformation. This opens a new avenue for investigations on topological effects arising from magnetic fields with aperiodic flux patterns or in disordered systems.
我们提出了一种在紧束缚系统中局部反转耦合项符号的方法，即通过插入一个精心设计的辅助位点并对所得顶点三重态进行本征模匹配。只要各个位点能够失谐，我们的技术就可以普遍应用于所有晶格构型。我们在激光写入的光子晶格中通过实验验证了该方法，并通过干涉测量确定了耦合的大小和符号。基于这些发现，我们展示了如何将这种通用的符号翻转耦合链路嵌入到扩展晶格结构中以施加Z₂规范变换。这为研究具有非周期磁通模式的磁场或无序系统中产生的拓扑效应开辟了一条新途径。
