Out-of-equilibrium dynamics of the XY spin chain from form factor expansion
Etienne Granet, Henrik Dreyer, Fabian H. L. Eßler
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 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 out-of-equilibrium expressions in the thermodynamic limit for the previously unknown order parameter 1-point function, dynamical 2-point function and equal-time 3-point function.
Topics & Concepts
Statistical physicsStructure factorPhysicsGaussianChain (unit)Thermodynamic limitLimit (mathematics)Classical XY modelCorrelation function (quantum field theory)Function (biology)AnisotropyMathematical physicsMathematicsQuantum mechanicsMathematical analysisCondensed matter physicsPhase transitionEvolutionary biologyBiologyDielectricQuantum many-body systemsOpinion Dynamics and Social InfluenceModel Reduction and Neural Networks