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科学家发现自旋-1/2 的双受激顶部布洛赫球上的许多拓扑区域
作者:小柯机器人 发布时间:2023/5/30 10:16:47

近日,加拿大麦克马斯特大学的J. Mumford研究小组取得一项新进展。经过不懈努力,他们发现了自旋-1/2 的双受激顶部(double-kicked top)布洛赫球上的许多拓扑区域。相关成果已于2023年5月23日在国际知名学术期刊《物理评论A》上发表。

据悉,Floquet拓扑系统已经被证实具有在传统拓扑系统中罕见的特点。其中之一是能够产生具有任意大卷绕数的拓扑相。这一特性在与自旋-1/2自由度耦合的量子双受激转子中得到了明显的体现。通过调节受激强度,可以实现大卷绕数。

该研究小组进一步将这一结果扩展到自旋1/2的量子双重受激转子,并发现该系统不仅表现出具有大卷绕数的拓扑区域,还需要大量的这些区域来全面描述转子在不同受激强度下布洛赫球顶部的拓扑性质。由于布洛赫球的几何特性,它被分割成具有不同拓扑性质的区域,而这些区域之间的边界则存在着0和π准能级束缚态。研究人员通过比较局部版本的平均场、量子和平均手性位移卷绕数,对这些区域进行了表征。此外,他们还采用一种探测态来观察系统的演化过程,以确定与束缚态有较大初始重叠的边界的位置。最后,他们还简要探讨了自旋-1/2的量子双受激转子与多步量子行走之间的关联,并将该系统置于当前一些实验探索拓扑相的背景之中。

附:英文原文

Title: Many topological regions on the Bloch sphere of the spin-1/2 double-kicked top

Author: J. Mumford

Issue&Volume: 2023/05/23

Abstract: Floquet topological systems have been shown to exhibit features not commonly found in conventional topological systems such as topological phases characterized by arbitrarily large winding numbers. This is clearly highlighted in the quantum double kicked rotor coupled to spin-1/2 degrees of freedom [Phys. Rev. A 97, 063603 (2018)] where large winding numbers are achieved by tuning the kick strengths. Here, we extend the results to the spin-1/2 quantum double kicked top and find not only does the system exhibit topological regions with large winding numbers, but a large number of them are needed to fully characterize the topology of the Bloch sphere of the top for general kick strengths. Due to the geometry of the Bloch sphere it is partitioned into regions with different topology and the boundaries separating them are home to 0 and π quasienergy bound states. We characterize the regions by comparing local versions of the mean field, quantum, and mean chiral displacement winding numbers. We also use a probe state to locate the boundaries by observing localization as the state evolves when it has a large initial overlap with bound states. Finally, we briefly discuss the connections between the spin-1/2 quantum double kicked top and multistep quantum walks, putting the system in the context of some current experiments in the exploration of topological phases.

DOI: 10.1103/PhysRevA.107.053316

Source: https://journals.aps.org/pra/abstract/10.1103/PhysRevA.107.053316

期刊信息

Physical Review A:《物理评论A》,创刊于1970年。隶属于美国物理学会,最新IF:2.97
官方网址:https://journals.aps.org/pra/
投稿链接:https://authors.aps.org/Submissions/login/new