Evidence from quantum Monte Carlo of large gap superfluidity and BCS-BEC crossover in double electron-hole layers

TL;DR

This paper uses quantum Monte Carlo simulations to demonstrate large gap superfluidity and a BCS-BEC crossover in electron-hole double layers, revealing universal behaviors similar to ultracold fermions and superconductors.

Contribution

It provides the first quantum Monte Carlo evidence of large gap superfluidity and details the evolution of superfluid parameters across the BCS-BEC crossover in electron-hole layers.

Findings

Large gap superfluidity exists over wide density ranges.

Superfluid parameters evolve from normal to BEC with decreasing density.

Strong Coulomb screening restricts the BCS state to a narrow density range.

Abstract

We report quantum Monte Carlo evidence of the existence of large gap superfluidity in electron-hole double layers over wide density ranges. The superfluid parameters evolve from normal state to BEC with decreasing density, with the BCS state restricted to a tiny range of densities due to the strong screening of Coulomb interactions, which causes the gap to rapidly become large near the onset of superfluidity. The superfluid properties exhibit similarities to ultracold fermions and iron-based superconductors, suggesting an underlying universal behavior of BCS-BEC crossovers in pairing systems.