ELFT HÍRADÓ

[tcsaba <tcsaba AT eik.bme.hu>]

                 M E G H Í V Ó - I N V I T A T I O N

    Seminar Series of the Department of Theoretical Physics at the
           Budapest University of Technology and Economics


                         Spyros Sotiriadis
                      (University of Ljubjana)


  Correlation Functions of the Quantum Sine-Gordon Model in and out of 
Equilibrium


Complete information on the equilibrium behaviour and dynamics of a 
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 analyse 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.

[arXiv:1802.08696]


Időpont: 2018. szeptember 28. péntek, 10:15
Helyszín: BME Fizikai Intézet, Elméleti Fizika Tanszék,
Budafoki út 8. F-épület, III lépcsőház, szemináriumi szoba