Dear All,
Monday’s statphys seminar will be given by Dr. Hideaki Obuse from Hokkaido University.
The announcement is also listed here.
sites.google.com/view/statphys-seminar <sites.google.com/view/statphys-seminar>
For those who wish to attend, e-mail me at
hatano@iis.u-tokyo.ac.jp <mailto:hatano@iis.u-tokyo.ac.jp>
for the zoom link.
Naomichi Hatano
皆様
１１月１日に午後１時から以下の通り統計力学セミナーを行います。
講演者は北大の小布施秀明さんです。講演の概要は
sites.google.com/view/statphys-seminar <sites.google.com/view/statphys-seminar>
でもご覧になれます。皆様お誘い合わせの上、是非ともご参加下さい。
参加ご希望の方は羽田野
hatano@iis.u-tokyo.ac.jp <mailto:hatano@iis.u-tokyo.ac.jp>
までご連絡頂ければ、折り返しzoomリンクをお送り致します。
羽田野
Date and Time: 1pm, Monday, Nov. 1
Speaker: Dr. Hideaki Obuse (Hokkaido Univ.)
Title: Non-Hermitian physics and non-unitary quantum walks
Abstract:
Recently, non-Hermitian physic which is related to open quantum systems has attracted great attention from the various fields of physics, i.e., condensed matter physics, classical and quantum optics, cold atoms, etc. While there are many experiments to imitate non-Hermitian Hamiltonians in classical systems, it is not easy to experimentally realize a true quantum system related to non-Hermitian Hamiltonians in a controlled way. At the moment, a discrete-time quantum walk (quantum walk, in short) by using entangled photons is one of the most ideal platforms to realize the non-Hermitian quantum system and study the novel phenomena in experiment.
In this talk, we introduce a non-unitary quantum walk to realize the non-Hermitian quantum system and explain various non-Hermitian phenomena by combining theoretical and experimental results. First, we explain the novel non-Hermitian topological phases for real gaps in the non-unitary quantum walks, i.e., the observation of topological edge states[1,2,3] and a breakdown of the bulk-edge correspondence[4]. Then, we explain the skin effect originating from the non-Hermitian topological phase for point gaps in the quantum walk[5]. Furthermore, we will also talk about that the localization-delocalization transition in the non-Hermitian one dimensional disordered system, which has been studied by a well known Hatano-Nelson tight-binding model so far, can be realized by using the non-unitary quantum walk[6].
[1] K. Mochizuki, D. Kim, and H. Obuse, Phys. Rev. A 93, 062116 (2016) <www.google.com/url?q=https%3A%2F%2Fdoi.org%2F10.1103%2FPhysRevA.93.062116&sa=D&sntz=1&usg=AFQjCNHMPsGfAAx57pJebnz-ba6nId9HTQ>.
[2] K. Mochizuki, D. Kim, N. Kawakami, and H. Obuse, Phys. Rev. A 102, 062202 (2020) <www.google.com/url?q=https%3A%2F%2Fdoi.org%2F10.1103%2FPhysRevA.102.062202&sa=D&sntz=1&usg=AFQjCNEi4LY5JdAvYzCgOkcNUoiSQDM-Iw>.
[3] L. Xiao, X. Zhan, Z.H. Bian, et al, Nature Phys. 13, 1117 (2017) <www.google.com/url?q=https%3A%2F%2Fdoi.org%2F10.1038%2Fnphys4204&sa=D&sntz=1&usg=AFQjCNGajpA8GDXgFQnkKM7-UeZfp3KGGw>.
[4] M. Kawasaki, K. Mochizuki, N. Kawakami, and H. Obuse, Prog. Theor. Exp. Phys. 2020, 12A105 (2020) <www.google.com/url?q=https%3A%2F%2Fdoi.org%2F10.1093%2Fptep%2Fptaa034&sa=D&sntz=1&usg=AFQjCNFMznuVSobhSYTA1ZK1xlWPhx80lA>.
[5] R. Okamoto, N. Kawakami, and H. Obuse (in preparation).
[6] N. Hatano and H. Obuse, Annals of Physics <www.google.com/url?q=https%3A%2F%2Fdoi.org%2F10.1016%2Fj.aop.2021.168615&sa=D&sntz=1&usg=AFQjCNHkgajJHk8RFzj5y1WyTJXeIFTMHA> (accepted, arXiv:2107.10420 <www.google.com/url?q=https%3A%2F%2Farxiv.org%2Fabs%2F2107.10420&sa=D&sntz=1&usg=AFQjCNHk_xMXbRkJlwc37Xj8A5MjgAnZhQ>).
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