Ergodicity breaking and deviation from eigenstate thermalization in relativistic quantum field theory
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.
2024
2024-04-05 10:08:58
1033
statistical physics, eigenstate thermalization, quantum field theory
statistična fizika, termalizacija lastnih stanj, kvantna teorija polja
dk_c
Miha
Srdinšek
70
Tomaž
Prosen
70
Spyros
Sotiriadis
70
UDK
4
536.93
ISSN pri članku
9
0031-9007
DOI
15
10.1103/PhysRevLett.132.021601
COBISS_ID
3
191511299
2303.15123.pdf
5224355
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0
Izvorni URL
2024-04-05 10:09:58