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Ergodicity Breaking and Deviation from Eigenstate Thermalization in Relativistic Quantum Field Theory.
Miha Srdinšek1,2,3, Tomaž Prosen4, Spyros Sotiriadis5,6
1Institut des Sciences du Calcul et des Données (ISCD), Sorbonne Université, 4 Place Jussieu, 75005 Paris, France.
Physical Review Letters
|January 26, 2024
Summary
The eigenstate thermalization hypothesis (ETH) in quantum systems is challenged by findings in relativistic quantum field theory. Researchers discovered exceptional quantum many-body scars, suggesting a violation of ETH in systems with quasiparticles.
Area of Science:
- Quantum Physics
- Statistical Mechanics
- Quantum Field Theory
Background:
- The eigenstate thermalization hypothesis (ETH) describes thermalization in quantum systems.
- ETH is expected to hold for ergodic quantum systems.
- Testing ETH in relativistic quantum field theory (QFT) is crucial for understanding thermalization.
Purpose of the Study:
- To test the validity of the eigenstate thermalization hypothesis (ETH) in a nonintegrable relativistic quantum field theory model.
- To investigate the nature of eigenstates in such systems and their deviation from thermal values.
Main Methods:
- Utilized Hamiltonian truncation, a numerical technique.
- Employed analytical arguments grounded in Lorentz symmetry and renormalization group theory.
- Examined matrix elements of local observables in energy eigenstates.
Main Results:
- Identified an infinite sequence of eigenstates exhibiting quantum many-body scars.
- These exceptional eigenstates have observable expectation values far from thermal averages.
- Demonstrated that these states correspond to one-quasiparticle states.
Conclusions:
- The strong version of the ETH is violated in relativistic QFTs that possess a quasiparticle description.
- Eigenstates in the thermodynamic limit span the region between one-quasiparticle states and thermal averages.
- Relativistic kinematics dictates the behavior of one-quasiparticle states, impacting ETH validity.
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