Mutual information scrambling in Ising spin chain

Abstract

We consider a chain of spin-half particles of a finite length, evolved with the mixed-field Ising Hamiltonian and impose open boundary condition. We simulate the time evolution of entanglement entropy and mutual information following quench from the N\'eel state in this system using tensor networks. We find that the entanglement entropy for non-integrable systems saturates to a constant value at late times, however it continues to oscillate for integrable systems. We also find that mutual information peaks as a function of distance between intervals decay faster for non-integrable systems compared to integrable systems, in agreement with the conclusion of \cite{Alba:2019ybw} for XXZ chains. We compare the oscillations in entanglement entropy evolution obtained from simulations in the integrable case with analytic results from quasi-particle picture and find agreement.