Ergodicity breaking and deviation from eigenstate thermalization in relativistic quantum field theory

Srdinšek, Miha (author), Prosen, Tomaž (author), Sotiriadis, Spyros (author)

The validity of the ergodic hypothesis in quantum systems can be rephrased in the form of the eigenstate thermalization hypothesis (ETH), a set of statistical properties for the matrix elements of local observables in energy eigenstates, which is expected to hold in any ergodic system. We test the ETH in a nonintegrable model of relativistic quantum field theory (QFT) using the numerical method of Hamiltonian truncation in combination with analytical arguments based on Lorentz symmetry and renormalization group theory. We find that there is an infinite sequence of eigenstates with the characteristics of quantum many-body scars—that is, exceptional eigenstates with observable expectation values that lie far from thermal values—and we show that these states are one-quasiparticle states. We argue that in the thermodynamic limit the eigenstates cover the entire area between two diverging lines: the line of one-quasiparticle states, whose direction is dictated by relativistic kinematics, and the thermal average line. Our results suggest that the strong version of the ETH is violated in any relativistic QFT whose spectrum admits a quasiparticle description.

• Language: English
• Keywords: statistical physics, eigenstate thermalization, quantum field theory
• Work type: Article
• Typology: 1.01 - Original Scientific Article
• Organization: FMF - Faculty of Mathematics and Physics
• Publication version: Author Accepted Manuscript
• Publication date: 12.01.2024
• Year: 2024
• Number of pages: Str. 021601-1-021601-7
• Numbering: Vol. 132, iss. 2
• PID: 20.500.12556/RUL-155535
• UDC: 536.93
• ISSN on article: 0031-9007
• DOI: 10.1103/PhysRevLett.132.021601
• COBISS.SI-ID: 191511299
• Publication date in RUL: 05.04.2024

Record is a part of a journal

• Title: Physical review letters
• Shortened title: Phys. rev. lett.
• Publisher: American Physical Society
• ISSN: 0031-9007
• COBISS.SI-ID: 1282575

Secondary language

• Language: Slovenian
• Keywords: statistična fizika, termalizacija lastnih stanj, kvantna teorija polja

Projects

• Funder: EC - European Commission
• Funding programme: European Commission
• Project number: 101030988
• Name: Tensor Network Truncated Conformal Space Approach
• Acronym: TNTCSA

• Funder: ARIS - Slovenian Research and Innovation Agency
• Project number: P1-0402-2019
• Name: Matematična fizika