Outofequilibrium dynamics of the XY spin chain from form factor expansion
Abstract
We consider the XY spin chain with arbitrary timedependent 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 outofequilibrium physics in this model. We show that $all$ correlation functions in the CE can be computed using form factor expansion and expressed in terms of Fredholm determinants. In particular, we present exact outofequilibrium expressions in the thermodynamic limit for the previously unknown order parameter onepoint function, dynamical twopoint function and equaltime threepoint function.
 Publication:

SciPost Physics
 Pub Date:
 January 2022
 DOI:
 10.21468/SciPostPhys.12.1.019
 arXiv:
 arXiv:2106.08359
 Bibcode:
 2022ScPP...12...19G
 Keywords:

 Condensed Matter  Statistical Mechanics;
 Mathematical Physics;
 Quantum Physics
 EPrint:
 44 pages