Report on scipost_202009_00014v1

Abstract

We compare the efficiency of different matrix product state (MPS) based methods for the calculation of two-time correlation functions in open quantum systems. The methods are the purification approach [1] and two approaches [2, 3] based on the Monte-Carlo wave function (MCWF) sampling of stochastic quantum trajectories using MPS techniques. We consider a XXZ spin chain either exposed to dephasing noise or to a dissipative local spin flip. We find that the preference for one of the approaches in terms of numerical efficiency depends strongly on the specific form of dissipation. 5.1 Comparison of stochastic approaches for the dephasing noise D 1 17 5.2 Comparison of Monte-Carlo wave function and purification method for D 1 18 5.3 Comparison of purification and stochastic approach for local dissipation D 2 22 6 Conclusion 26 References 26