Mobile small bipolarons on a three-dimensional cubic lattice

TL;DR

This paper employs quantum Monte Carlo simulations to investigate the properties of small bipolarons in three-dimensional lattices, revealing conditions conducive to high-temperature bipolaron superconductivity.

Contribution

It provides the first numerically exact analysis of bipolaron size and mass in 3D, showing they can be small and light at intermediate coupling, unlike previous perturbative approaches.

Findings

Bipolarons can be both small and light at intermediate coupling.

Transition temperatures estimated between 90-120 K.

Results are robust against Coulomb repulsion and impurities.

Abstract

We use numerically exact quantum Monte Carlo (QMC) to compute the properties of three-dimensional bipolarons for interaction strengths where perturbation theory fails. For intermediate electron-phonon coupling and Hubbard U, we find that bipolarons can be both small and light, a prerequisite for bipolaron superconductivity. We use the QMC results to make estimates of transition temperatures, which peak at between 90-120 K and are demonstrated to be insensitive to Coulomb repulsion and impurities.