KIP publications

year 2018
author(s) Aleksandr N. Mikheev, Christian-Marcel Schmied, and Thomas Gasenzer
title Low-energy effective theory of non-thermal fixed points in a multicomponent Bose gas
KIP-Nummer HD-KIP 18-80
KIP-Gruppe(n) F20,F27
document type Paper
Keywords (shown) Condensed Matter - Quantum Gases, Condensed Matter - Statistical Mechanics, High Energy Physics - Phenomenology
source arXiv:1807.10228 [cond-mat.quant-gas]
Abstract (en)

Non-thermal fixed points in the evolution of a quantum many-body system quenched far out of equilibrium manifest themselves in a scaling evolution of correlations in space and time. We develop a low-energy effective theory of non-thermal fixed points in a bosonic quantum many-body system by integrating out long-wave-length density fluctuations. The system consists of N distinguishable spatially uniform Bose gases with O(N)×U(1)-symmetric interactions. The effective theory describes interacting Goldstone modes of the total and relative-phase excitations. It is similar in character to the non-linear Luttinger-liquid description of low-energy phonons in a single dilute Bose gas, with the markable difference of a universal non-local coupling function depending, in the large-N limit, only on momentum, single-particle mass, and density of the gas. Our theory provides a perturbative description of the non-thermal fixed point, technically easy to apply to experimentally relevant cases with a small number of fields N. Numerical results for N=3 allow us to characterize the analytical form of the scaling function and confirm the analytically predicted scaling exponents. The fixed point which is dominated by the relative phases is found to be Gaussian, while a non-Gaussian fixed point is anticipated to require scaling evolution with a distinctly lower power of time.

  author   = {{Mikheev}, A.~N. and {Schmied}, C.-M. and {Gasenzer}, T.},
  title    = {"{Low-energy effective theory of non-thermal fixed points in a multicomponent Bose gas}"},
  journal  = {Physical Review A, arXiv:1807.10228 [cond-mat.quant-gas]},
  year     = {2018},
  volume   = {},
  pages    = {},
  month    = {jul},
  url      = {}
URL arXiv:1807.10228 [cond-mat.quant-gas]
Datei pdf
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