Describing systems of interacting fermions by boson models: exact mapping in arbitrary dimension and applications

TL;DR

This paper introduces an exact method to map interacting fermion models onto bosonic models in any dimension, enabling new analytical and computational approaches, including sign-problem-free Monte Carlo simulations.

Contribution

The authors develop a novel exact mapping from fermionic to bosonic models applicable in arbitrary dimensions, with potential for improved computational techniques.

Findings

Diagrammatic perturbation theory matches fermionic results

Proposed Monte Carlo scheme is free of the fermionic sign problem

Bosonic representation facilitates efficient computations

Abstract

We develop a new method that allows us to map models of interacting fermions onto bosonic models describing collective excitations in an arbitrary dimension. This mapping becomes exact in the thermodynamic continuous time limit. The boson models can be written either in the form of a model of non-interacting bosons in a fluctuating auxiliary field or in the form of a superfield theory of interacting bosons. We show how one can study the latter version using perturbation theory. Using the developed diagrammatic technique we compared the first two orders of perturbation theory with the corresponding results for the original fermion model and found a perfect agreement. As concerns the former representation, we suggest a scheme that may be suitable for Monte Carlo simulations and demonstrate that it is free of the fermionic sign problem. We discuss in details the properties of the bosonic representation and argue that there should not be any obstacles preventing from an efficient computation.