Flat histogram quantum Monte Carlo for analytic continuation to real time

We study a recently developed technique based on the application of flat histogram ideas to quantum Monte Carlo. We use this technique to make the histogram of the single-particle Green's function flat as a function of the imaginary time, and the stochastic analytical inference technique to obtain the spectral functions for the $t-J$ model. We find that this application of the flat histogram idea to the quantum Monte Carlo method dramatically improves the quality of the results of the analytic continuation.