报告人: Masahito Ueda (Department of Physics, The University of Tokyo and RIKEN CEMS)

报告时间: 2025年5月08日 14:00

报告地点: 物理楼W105

Abstract:
Topological phases of matter have been actively studied in physics for decades. Since the discovery of the quantum Hall effect, it has been recognized that topological structures in quantum and classical systems lead to robust physical phenomena. The general concept of topology can be utilized to classify not only static phases but also nonequilibrium dynamical phases. In fact, several important classes of nonequilibrium topological phases have been found in periodically driven systems [1] and non-Hermitian systems [2]. While dynamical control of topological phases has many practical applications such as photo-induced topological phase transitions [3] and topological lasers [4], out-of-equilibrium systems can exhibit genuinely dynamical topological phases that have no static analogues [1, 2, 5]. Thus, finding a new class of nonequilibrium topological phases not only provides a novel way of control of topological phases, but also expands the scope of topological phases of matter. In this talk, we develop a general framework to classify topology of quantum channels for discrete quantum feedback control, construct prototypical models of topological feedback control using Maxwell’s demon, and report discovery of a new class of genuinely dynamical topological phases [6].

[1] T. Kitagawa et al., Phys. Rev. B 82, 235114 (2010).
[2] Z. Gong et al., Phys. Rev. X 8, 031079 (2018).
[3] T. Oka and H. Aoki, Phys. Rev. B 79, 081406 (2009).
[4] M. A. Banders et al., Science 359, 6381 (2018).
[5] M. S. Rudner et al., Phys. Rev. X 3, 031005 (2013).
[6] M. Nakagawa and M. Ueda, Phys. Rev. X 15, 021016 (2015).