Comprehensive study of Frohlich polaron

TL;DR

This paper advances the understanding of Frohlich polarons by developing improved quantum Monte Carlo methods, providing precise data on their energy and mass, and analyzing their spectral properties at various coupling strengths.

Contribution

It introduces enhanced diagrammatic quantum Monte Carlo techniques with new estimators and spectral analysis, offering the most accurate data on polaron energy, mass, and spectral features to date.

Findings

Accurate binding energy data for Frohlich polarons.

Precise effective mass measurements across coupling regimes.

Identification of spectral peaks related to unstable excited states.

Abstract

A detailed study of the Frohlich polaron model is performed on the basis of diagrammatic quantum Monte Carlo method. The method is further developed both quantitatively (performance) and qualitatively (new estimators), and is enhanced by spectral analysis of the polaron Green function, within a novel approach. We present the best up to date results for the binding energy, and for the first time make available precise data for the effective mass, including the region of intermediate and strong couplings. We look at the structure of the polaron cloud and answer such questions as the average number of phonons in the cloud and their number/momentum distribution. The spectral analysis reveals non-trivial structure of the spectral density at intermediate and large coupling: the spectral continuum features pronounced peaks that we attribute to unstable excited states of the polaron.