Condensation of classical nonlinear waves
Abstract
We study the formation of a large-scale coherent structure (a condensate) in classical wave equations by considering the defocusing nonlinear Schr\"odinger equation as a representative model. We formulate a thermodynamic description of the condensation process by using a wave turbulence theory with ultraviolet cut-off. In 3 dimensions the equilibrium state undergoes a phase transition for sufficiently low energy density, while no transition occurs in 2 dimensions, in analogy with standard Bose-Einstein condensation in quantum systems. Numerical simulations show that the thermodynamic limit is reached for systems with computational modes and greater. On the basis of a modified wave turbulence theory, we show that the nonlinear interaction makes the transition to condensation subcritical. The theory is in quantitative agreement with the simulations.
Cite
@article{arxiv.cond-mat/0502499,
title = {Condensation of classical nonlinear waves},
author = {Colm Connaughton and Christophe Josserand and Antonio Picozzi and Yves Pomeau and Sergio Rica},
journal= {arXiv preprint arXiv:cond-mat/0502499},
year = {2009}
}