Theoretical study of disorder-free localization in artificial quantum many-body systems

2022 Fiscal Year Final Research Report

• Project/Area Number: 21K13849
• Research Category: Grant-in-Aid for Early-Career Scientists
• Allocation Type: Multi-year Fund
• Review Section: Basic Section 13010:Mathematical physics and fundamental theory of condensed matter physics-related
• Research Institution: Akita University
• Principal Investigator: Kuno Yoshihito 秋田大学, 理工学研究科, 講師 (30753628)
• Project Period (FY): 2021-04-01 – 2023-03-31
• Keywords: 人工量子多体 / 多体局在 / アンダーソン局在 / 非平衡ダイナミクス

Outline of Final Research Achievements

We studied theoretical models of artificial quantum many-body systems that can be constructed in artificial quantum system such as photonic crystals and coldatoms atoms in an optical lattice. We clarified the presence of novel localization and many-body localization phenomena without disorder. In particular, we have focused on theoretical models for complete flat-band system and nontrivial integrable systems with many-body interactions, carried out numerical calculations. The numerical calculations characterized the presence of novel localization and many-body localization phenomena without disorder. Furthermore, detailed analysis of nonequilibrium dynamics reveals that the tripartite mutual information is much efficient quantity to characterize the localization properties regardless of the initial state. Finally, we focused on a measurement induce phase transition in a quasi-integrable system. We showed that the tripartite mutual information is good indicator to detect localization.

Free Research Field

数理物理・物性基礎

Academic Significance and Societal Importance of the Research Achievements

これまで局在や多体局在現象は不純物ポテンシャルに起因して起きるものと考えられていたが、本研究においてはフラットバンド上のコンパクト固有状態の存在や多体相互作用によって並進対称性を保ったまま局在や多体局在現象が起きるという実例を示した. この成果は従来の局在物理では考えられていなかった新奇な局在の発現機構を例示したという点で学術的意義がある。また、このような多体局在現象は初期の量子状態を保護する機構も持っており今回の不純物ポテンシャルによらない局在現象の発現は単一サンプルで初期の量子情報の保持につながる可能性がある. この性質は量子デバイスの開発などへの応用も期待され社会的意義もある.