Supersymmetric Polarization Anomaly in Photonic Discrete-Time Quantum Walks.
Supersymmetric Polarization Anomaly in Photonic Discrete-Time Quantum Walks.
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DOI：
10.1103/physrevlett.121.260501
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发表时间：
2018-04
影响因子：
8.6
通讯作者：
S. Barkhofen;L. Lorz;Thomas Nitsche;C. Silberhorn;H. Schomerus
中科院分区：
文献类型：
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作者：
S. Barkhofen;L. Lorz;Thomas Nitsche;C. Silberhorn;H. Schomerus
量子反常导致有限的期望值，这违背了系统的表观对称性。这些异常是电子、光子和原子系统中拓扑效应的核心，它们导致对外部场的独特响应，但通常无法直接观察到。在这里，我们实现了一个离散时间量子行走的光学网络实现，这样的异常可以直接观察到的拓扑midgap状态的独特的圆偏振。我们的基础上，一个单一的步骤协议克服了早期的多步骤协议的实验不可行的系统。这种演化结合了手征对称性和以前未被探索过的超对称性的幺正形式。实验获得的位置和硬币状态的步行者，我们进行了全面的偏振断层扫描，并提供证据的预测异常的midgap状态。这种方法为动态提取拓扑态以应用于量子信息开辟了前景。
Quantum anomalies lead to finite expectation values that defy the apparent symmetries of a system. These anomalies are at the heart of topological effects in electronic, photonic, and atomic systems, where they result in a unique response to external fields but generally escape a more direct observation. Here, we implement an optical-network realization of a discrete-time quantum walk, where such an anomaly can be observed directly in the unique circular polarization of a topological midgap state. We base the system on a single-step protocol overcoming the experimental infeasibility of earlier multistep protocols. The evolution combines a chiral symmetry with a previously unexplored unitary version of supersymmetry. Having experimental access to the position and the coin state of the walker, we perform a full polarization tomography and provide evidence for the predicted anomaly of the midgap states. This approach opens the prospect to dynamically distill topological states for quantum information applications.