paper

Out-of-equilibrium dynamics of the XY spin chain from form factor expansion

arXiv:2106.08359 · doi:10.21468/SciPostPhys.12.1.019

Abstract

We consider the XY spin chain with arbitrary time-dependent magnetic field and anisotropy. We argue that a certain subclass of Gaussian states, called Coherent Ensemble (CE) following [1], provides a natural and unified framework for out-of-equilibrium physics in this model. We show that correlation functions in the CE can be computed using form factor expansion and expressed in terms of Fredholm determinants. In particular, we present exact out-of-equilibrium expressions in the thermodynamic limit for the previously unknown order parameter one-point function, dynamical two-point function and equal-time three-point function.

44 pages

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