Mittal Vikash, Raj Aswathy, Dey Sanjib, Goyal Sandeep K
Department of Physical Sciences, Indian Institute of Science Education & Research (IISER) Mohali, Sector 81 SAS Nagar, PO 140306, Manauli, Punjab, India.
Okinawa Institute of Science and Technology Graduate University, Okinawa, 904-0495, Japan.
Sci Rep. 2021 May 13;11(1):10262. doi: 10.1038/s41598-021-89441-8.
Discrete-time quantum walks are known to exhibit exotic topological states and phases. Physical realization of quantum walks in a lossy environment may destroy these phases. We investigate the behaviour of topological states in quantum walks in the presence of a lossy environment. The environmental effects in the quantum walk dynamics are addressed using the non-Hermitian Hamiltonian approach. We show that the topological phases of the quantum walks are robust against moderate losses. The topological order in one-dimensional split-step quantum walk persists as long as the Hamiltonian respects exact [Formula: see text]-symmetry. Although the topological nature persists in two-dimensional quantum walks as well, the [Formula: see text]-symmetry has no role to play there. Furthermore, we observe topological phase transition in two-dimensional quantum walks that is induced by losses in the system.
已知离散时间量子行走会展现出奇异的拓扑态和相。在有损环境中量子行走的物理实现可能会破坏这些相。我们研究在存在有损环境的情况下量子行走中拓扑态的行为。使用非厄米哈密顿量方法来处理量子行走动力学中的环境效应。我们表明量子行走的拓扑相对适度损耗具有鲁棒性。只要哈密顿量尊重精确的[公式：见正文]对称性，一维分步量子行走中的拓扑序就会持续存在。尽管拓扑性质在二维量子行走中也会持续存在，但[公式：见正文]对称性在那里不起作用。此外，我们观察到二维量子行走中由系统损耗引起的拓扑相变。
