Topological phases of quantum walks and how they can be detected
Janos Asboth (Wigner Research Centre for Physics & Budapest University, Hungary)
Quantum walks are versatile toy models for periodically driven systems in the nonperturbative regime of low-frequency and high-intensity drive. In this regime, systems can have "hidden" topological invariants: they can host topologically protected edge states even if their effective Hamiltonian is topologically trivial. I will discuss schemes we developed [1,2] to measure the bulk topological invariants, including the "hidden" ones, directly, which also work in the case with spatial disorder, and which have recently been measured in quantum walk experiments[3,4].
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: Zhan, X., Xiao, L., Bian, Z., Wang, K., Qiu, X., Sanders, B.C., Yi, W. and Xue, P.: Detecting topological invariants in nonunitary discrete-time quantum walks. Phys Rev Lett, 119(13), 130501
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