Entanglement dynamics of thermofield double states in integrable models

Abstract We study the entanglement dynamics of thermofield double (TFD) states in integrable spin chains and quantum field theories. show that, for a natural choice Hamiltonian eigenbasis, TFD evolution may be interpreted as quench from an initial state which is low-entangled real-space representation displays simple quasiparticle structure. Based on semiclassical picture analogous to one developed standard quenches, we conjecture formula dynamics, valid both discrete continuous theories, expected exact scaling limit large space time scales. test our two prototypical examples chains, where numerical tests are possible. First, XY-model, compare predictions with results obtained by mapping system free fermions, finding excellent agreement. Second, interacting XXZ Heisenberg model, against iTEBD calculations. For latter, generally find good agreement, although, some range parameters within accessible simulation times, small discrepancies visible, attribute finite-time effects.