# Compressing Green's function using intermediate representation between imaginary-time and real-frequency domains

## TL;DR

This paper introduces an intermediate representation (IR) for compressing imaginary-time data, significantly improving the efficiency of quantum Monte Carlo calculations for many-body systems.

## Contribution

The authors develop a model-independent IR method that compactly represents correlation functions, enhancing the analysis of quantum Monte Carlo data.

## Key findings

- IR provides a significantly more compact form of correlation functions.
- IR improves the efficiency of quantum Monte Carlo calculations.
- The framework can be broadly applied to many-body system analyses.

## Abstract

New model-independent compact representations of imaginary-time data are presented in terms of the intermediate representation (IR) of analytical continuation. This is motivated by a recent numerical finding by the authors [J. Otsuki et al., arXiv:1702.03056]. We demonstrate the efficiency of the IR through continuous-time quantum Monte Carlo calculations of an Anderson impurity model. We find that the IR yields a significantly compact form of various types of correlation functions. The present framework will provide general ways to boost the power of cutting-edge diagrammatic/quantum Monte Carlo treatments of many-body systems.