III Physikalisches Institut, Research Center SCOPE, and MPI for Solid State Research, University of Stuttgart, Pfaffenwaldring 57, 70569 Stuttgart, Germany and ICFO-Institut de Ciències Fotòniques, Mediterranean Technology Park, E-08860 Castelldefels, Barcelona, Spain.
III Physikalisches Institut, Research Center SCOPE, and MPI for Solid State Research, University of Stuttgart, Pfaffenwaldring 57, 70569 Stuttgart, Germany.
Phys Rev Lett. 2014 Mar 28;112(12):120502. doi: 10.1103/PhysRevLett.112.120502. Epub 2014 Mar 26.
Phases of matter with nontrivial topological order are predicted to exhibit a variety of exotic phenomena, such as robust localized bound states in 1D systems, and edge states in 2D systems, which are expected to display spin helicity, immunity to backscattering, and weak antilocalization. In this Letter, we present an experimental observation of topological structures generated via the controlled implementation of two consecutive noncommuting rotations in photonic discrete-time quantum walks. The second rotation introduces valleylike Dirac points in the system, allowing us to create the nontrivial topological pattern. By choosing specific values for the rotations, it is possible to coherently drive the system between topological sectors characterized by different topological invariants. We probe the full topological landscape, demonstrating the emergence of localized bound states hosted at the topological boundaries, and the existence of extremely localized or delocalized non-Gaussian quantum states. Our results pave the way for the study of valley polarization and applications of topological mechanisms in robust optical-device engineering.
具有非平凡拓扑序的物质相预计会表现出各种奇异现象，例如在一维系统中存在鲁棒的局域束缚态，在二维系统中存在边缘态，这些边缘态预计会表现出自旋螺旋性、对背散射的免疫性和弱反局域性。在这篇文章中，我们通过在光子离散时间量子行走中连续执行两次非对易旋转的受控实现，展示了拓扑结构的实验观测。第二次旋转在系统中引入了类似山谷的狄拉克点，使我们能够创建非平凡的拓扑模式。通过选择旋转的特定值，我们可以在由不同拓扑不变量表征的拓扑区域之间相干地驱动系统。我们探测了完整的拓扑景观，展示了局域束缚态出现在拓扑边界处，以及存在极度局域化或非局域化的非高斯量子态。我们的结果为谷极化的研究和拓扑机制在鲁棒光学器件工程中的应用铺平了道路。
