Jahr 2016
Autor(en) M. Karl and T. Gasenzer
Titel Strongly anomalous non-thermal fixed point in a quenched two-dimensional Bose gas
KIP-Nummer HD-KIP 16-110
KIP-Gruppe(n) F17,F27,P2
Dokumentart Paper
Keywords Condensed Matter - Quantum Gases, Condensed Matter - Statistical Mechanics, Physics - Fluid Dynamics
Quelle New J. Phys. 19 (2017) 093014
doi 10.1088/1367-2630/aa7eeb
Abstract (en)

Universal scaling behavior in the relaxation dynamics of an isolated two-dimensional Bose gas is studied by means of semi-classical stochastic simulations of the Gross-Pitaevskii model. The system is quenched far out of equilibrium by imprinting vortex defects into an otherwise phase-coherent condensate. A strongly anomalous non-thermal fixed point is identified, associated with a slowed decay of the defects in the case that the dissipative coupling to the thermal background noise is suppressed. At this fixed point, a large anomalous exponent η ≃ −3 and, related to this, a large dynamical exponent z ≃ 5 are identified. The corresponding power-law decay is found to be consistent with three-vortex-collision induced loss. The article discusses these aspects of non-thermal fixed points in the context of phase-ordering kinetics and coarsening dynamics, thus relating phenomenological and analytical approaches to classifying far-from-equilibrium scaling dynamics with each other. In particular, a close connection between the anomalous scaling exponent η, introduced in a quantum-field theoretic approach, and conservation-law induced scaling in classical phase-ordering kinetics is revealed. Moreover, the relation to superfluid turbulence as well as to driven stationary systems is discussed.

URL arXiv:1611.01163 [cond-mat.quant-gas]
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