Correlation functions of the quantum sine-Gordon model in and out of equilibrium
ID Kukuljan, Ivan (Author), ID Sotiriadis, Spyros (Author), ID Takács, Gábor (Author)

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Complete information on the equilibrium behavior and dynamics of quantum field theory (QFT) is provided by multipoint correlation functions. However, their theoretical calculation is a challenging problem, even for exactly solvable models. This has recently become an experimentally relevant problem, due to progress in cold-atom experiments simulating QFT models and directly measuring higher order correlations. Here we compute correlation functions of the quantum sine-Gordon model, a prototype integrable model of central interest from both theoretical and experimental points of view. Building upon the so-called truncated conformal space approach, we numerically construct higher order correlations in a system of finite size in various physical states of experimental relevance, both in and out of equilibrium. We measure deviations from Gaussianity due to the presence of interaction and analyze their dependence on temperature, explaining the experimentally observed crossover between Gaussian and non-Gaussian regimes. We find that correlations of excited states are markedly different from the thermal case, which can be explained by the integrability of the system. We also study dynamics after a quench, observing the effects of the interaction on the time evolution of correlation functions, their spatial dependence, and their non-Gaussianity as measured by the kurtosis.

Keywords:statistical mechanics, quantum mechanics, quantum field theory, integrable models
Typology:1.01 - Original Scientific Article
Organization:FMF - Faculty of Mathematics and Physics
Publication status:Published
Publication version:Author Accepted Manuscript
Number of pages:Str. 110402-1-110402-7
Numbering:Vol. 121, iss. 11
PID:20.500.12556/RUL-104060 This link opens in a new window
ISSN on article:0031-9007
DOI:10.1103/PhysRevLett.121.110402 This link opens in a new window
COBISS.SI-ID:3251556 This link opens in a new window
Publication date in RUL:03.10.2018
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Record is a part of a journal

Title:Physical review letters
Shortened title:Phys. rev. lett.
Publisher:American Physical Society
COBISS.SI-ID:1282575 This link opens in a new window

Secondary language

Keywords:statistična mehanika, kvantna mehanika, kvantna teorija polja, integrabilni modeli


Funder:EC - European Commission
Funding programme:H2020
Project number:694544
Name:Open many-body non-equilibrium systems

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