Observation of topologically protected bound states in photonic quantum walks
Observation of topologically protected bound states in photonic quantum walks
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DOI：
10.1038/ncomms1872
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发表时间：
2012-06-01
影响因子：
16.6
通讯作者：
White, Andrew G.
中科院分区：
文献类型：
--
作者：
Kitagawa, Takuya;Broome, Matthew A.;White, Andrew G.
拓扑相展示了现代物理学中一些最引人注目的现象。量子霍尔系统、拓扑绝缘体和拓扑超导体的许多丰富行为都可以追溯到不同拓扑相之间界面上鲁棒束缚态的存在。这种鲁棒性在计量学中得到了应用，并有望在未来的量子计算中得到应用。工程量子系统——特别是在光子学领域，可以直接观察波函数——为创建和探测各种拓扑相提供了通用平台。在这里，我们使用光子量子行走来观察具有不同体拓扑特性的系统之间的束缚态，并证明它们对扰动的鲁棒性——拓扑保护的标志。尽管通常在静态（与时间无关）系统中讨论这种束缚态，但在这里我们证明了它们在明确与时间相关的情况下的存在。此外，我们发现了一个新现象：周期性驱动系统特有的一对受拓扑保护的束缚态。
Topological phases exhibit some of the most striking phenomena in modern physics. Much of the rich behaviour of quantum Hall systems, topological insulators, and topological superconductors can be traced to the existence of robust bound states at interfaces between different topological phases. This robustness has applications in metrology and holds promise for future uses in quantum computing. Engineered quantum systems-notably in photonics, where wavefunctions can be observed directly-provide versatile platforms for creating and probing a variety of topological phases. Here we use photonic quantum walks to observe bound states between systems with different bulk topological properties and demonstrate their robustness to perturbations-a signature of topological protection. Although such bound states are usually discussed for static (time-independent) systems, here we demonstrate their existence in an explicitly time-dependent situation. Moreover, we discover a new phenomenon: a topologically protected pair of bound states unique to periodically driven systems.