Quantum Monte Carlo results for bipolaron stability in quantum dots

TL;DR

This paper uses quantum Monte Carlo simulations to study how quantum dot confinement affects bipolaron stability, revealing that confinement can both hinder and promote bipolaron formation depending on the coupling strength.

Contribution

It provides the first detailed quantum Monte Carlo analysis of bipolaron stability in confined quantum dot systems, accounting for quantum lattice fluctuations.

Findings

Confinement opposes bipolaron formation at weak coupling.

Confinement promotes bipolaron binding at intermediate to strong coupling.

System tuning reduces the Frohlich coupling needed for bipolaron stability.

Abstract

Bipolaron formation in a two-dimensional lattice with harmonic confinement, representing a simplified model for a quantum dot, is investigated by means of quantum Monte Carlo simulations. This method treats all interactions exactly and takes into account quantum lattice fluctuations. Calculations of the bipolaron binding energy reveal that confinement opposes bipolaron formation for weak electron-phonon coupling, but abets a bound state at intermediate to strong coupling. Tuning the system from weak to strong confinement gives rise to a small reduction of the minimum Frohlich coupling parameter for the existence of a bound state.