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Seminarium ISQI - Dr Ken Imura

From topological matter to non-Hermitian quantum mechanics

Dr. Ken Imura (University of Tokyo)

Date, Time: 30.04, 15:00 - 16:00

Topological properties of topological matter are protected by the topology of the relevant wave functions, which do no change unless the system is perturbed so strongly that the bulk energy gap closes (as a result, related bands get inverted, etc.). In ref. [1], using such a protected topological property, we have proposed a recipe for realizing an ultra-low-energy consuming nanocircuit on terraces of a weak topological insulator. In refs. [2-3], topological insulator and Weyl semimetal thin (nano-) films have been studied from the viewpoint of the dimensional crossover of topological properties in these systems. In ref. [4] the idea of topological insulator has been generalized to non-Hermitian systems. In this seminar, in addition to a review of these works on topological matter, if time allows, I will briefly discuss our recent work [5] on the entanglement dynamics in a (Hatano-Nelson type [6]) non-Hermitian system.

[1] Yoshimura, et al. “Perfectly conducting channel on the dark surface of weak topological insulators,” Phys. Rev. B 88, 045408 (2013).

[2] Kobayashi et al., “Dimensional crossover of transport characteristics in topological insulator nanofilms,” Phys. Rev. B 92, 235407 (2015).

[3] Yoshimura, et al. “Comparative study of Weyl semimetal and topological/Chern insulators: Thin-film point of view,”

Phys. Rev. B. 94, 235414 (2016).

[4] Imura and Takane, “Generalized bulk-edge correspondence for non-Hermitian topological systems,” Phys. Rev. B 100, 165430 (2019).

[5] Orito and Imura, “Entanglement dynamics in the many-body Hatano-Nelson model”, Phys. Rev. B 108, 214308 (2023).

[6] N. Hatano, D.R. Nelson, “Localization Transitions in Non-Hermitian Quantum Mechanics,” Phys. Rev. Lett., 77, 570 (1996).