# Exact real-time dynamics of single-impurity Anderson model from a single-spin hybridization-expansion

## TL;DR

This paper introduces a modified quantum Monte Carlo solver for the time-dependent single-impurity Anderson model, reducing computational complexity and enabling longer simulation times.

## Contribution

The authors develop a semi-analytical hybridization-expansion quantum Monte Carlo method that improves efficiency by focusing on one spin channel, extending simulation capabilities.

## Key findings

- Enables simulation of longer time scales in impurity models.
- Reduces the dynamical sign problem in quantum Monte Carlo simulations.
- Successfully applied to calculate electric current in impurity systems.

## Abstract

In this work we introduce a modified real-time continuous-time hybridization-expansion quantum Monte Carlo solver for a time-dependent single-orbital Anderson impurity model: CT-1/2-HYB-QMC. In the proposed method the diagrammatic expansion is performed only for one out of the two spin channels, while the resulting effective single-particle problem for the other spin is solved semi-analytically for each expansion diagram. CT-1/2-HYB-QMC alleviates the dynamical sign problem by reducing the order of sampled diagrams and makes it possible to reach twice as long time scales in comparison to the standard CT-HYB method. We illustrate the new solver by calculating an electric current through impurity in paramagnetic and spin-polarized cases.