A continuous-time solver for quantum impurity models

TL;DR

This paper introduces a new continuous-time solver for quantum impurity models that uses stochastic sampling, offering high accuracy and efficiency for low-temperature and strongly interacting systems, and enabling precise analysis of metal-insulator transitions.

Contribution

The paper presents a novel continuous-time impurity solver based on stochastic sampling, improving efficiency and accuracy over existing methods for dynamical mean field theory applications.

Findings

Accurately reproduces quantum Monte Carlo and exact diagonalization results.

Efficiently handles low temperatures and strong interactions.

Enables precise determination of the metal-insulator transition temperature.

Abstract

We present a new continuous time solver for quantum impurity models such as those relevant to dynamical mean field theory. It is based on a stochastic sampling of a perturbation expansion in the impurity-bath hybridization parameter. Comparisons to quantum Monte Carlo and exact diagonalization calculations confirm the accuracy of the new approach, which allows very efficient simulations even at low temperatures and for strong interactions. As examples of the power of the method we present results for the temperature dependence of the kinetic energy and the free energy, enabling an accurate location of the temperature-driven metal-insulator transition.