Single-quasiparticle eigenstate thermalization

Tokarczyk, Piotr (author), Vidmar, Lev (author), Łydżba, Patrycja (author)

Quadratic Hamiltonians that exhibit single-particle quantum chaos are called quantum-chaotic quadratic Hamiltonians. One of their hallmarks is single-particle eigenstate thermalization introduced in Łydżba et al. [Phys. Rev. B 104, 214203 (2021)], which describes statistical properties of matrix elements of observables in single-particle eigenstates. However, the latter has been studied only in quantum-chaotic quadratic Hamiltonians that obey the U(1) symmetry. Here, we focus on quantum-chaotic quadratic Hamiltonians that break the U(1) symmetry and, hence, their “single-particle” eigenstates are actually single-quasiparticle excitations introduced on the top of a many-body state. We study their wave functions and matrix elements of one-body observables, for which we introduce the notion of single-quasiparticle eigenstate thermalization. Focusing on spinless fermion Hamiltonians in three dimensions with local hopping, pairing, and on-site disorder, we also study the properties of disorder-induced near zero modes, which give rise to a sharp peak in the density of states at zero energy. Finally, we numerically show equilibration of observables in many-body eigenstates after a quantum quench. We argue that the latter is a consequence of single-quasiparticle eigenstate thermalization, in analogy to the U(1) symmetric case from Łydżba et al. [Phys. Rev. Lett. 131, 060401 (2023)].

• Language: English
• Keywords: statistical physics
• Work type: Article
• Typology: 1.01 - Original Scientific Article
• Organization: FMF - Faculty of Mathematics and Physics
• Publication version: Author Accepted Manuscript
• Publication date: 05.02.2024
• Year: 2024
• Number of pages: Str. 024102-1-024102-17
• Numbering: Vol. 109, iss. 2
• PID: 20.500.12556/RUL-155998
• UDC: 536.9
• ISSN on article: 2470-0045
• DOI: 10.1103/PhysRevE.109.024102
• COBISS.SI-ID: 193901571
• Publication date in RUL: 26.04.2024

Record is a part of a journal

• Title: Physical review
• Shortened title: Phys. rev., E
• Publisher: American Physical Society
• ISSN: 2470-0045
• COBISS.SI-ID: 2048366611

Secondary language

• Language: Slovenian
• Keywords: statistična fizika