Quantum quenches in extended systems

Abstract

We study in general the time-evolution of correlation functions in a extended\nquantum system after the quench of a parameter in the hamiltonian. We show that\ncorrelation functions in d dimensions can be extracted using methods of\nboundary critical phenomena in d+1 dimensions. For d=1 this allows to use the\npowerful tools of conformal field theory in the case of critical evolution.\nSeveral results are obtained in generic dimension in the gaussian (mean-field)\napproximation. These predictions are checked against the real-time evolution of\nsome solvable models that allows also to understand which features are valid\nbeyond the critical evolution.\n All our findings may be explained in terms of a picture generally valid,\nwhereby quasiparticles, entangled over regions of the order of the correlation\nlength in the initial state, then propagate with a finite speed through the\nsystem. Furthermore we show that the long-time results can be interpreted in\nterms of a generalized Gibbs ensemble. We discuss some open questions and\npossible future developments.\n