Diffusion Monte Carlo study of strongly interacting two-dimensional Fermi gases

TL;DR

This study uses diffusion Monte Carlo methods to analyze the properties of strongly interacting two-dimensional Fermi gases at zero temperature, providing insights into their energy, pairing gap, and Tan's contact across the BEC-BCS crossover.

Contribution

It presents the first ab initio diffusion Monte Carlo calculations for 2D strongly interacting Fermi gases, including energy, pairing gap, and Tan's contact, connecting finite-size systems to the thermodynamic limit.

Findings

Energy results across the BEC-BCS crossover

Equation of state parametrization for 2D Fermi gases

Calculated pairing gap in the strong coupling regime

Abstract

Ultracold atomic Fermi gases have been a popular topic of research, with attention being paid recently to two-dimensional (2D) gases. In this work, we perform T=0 ab initio diffusion Monte Carlo calculations for a strongly interacting two-component Fermi gas confined to two dimensions. We first go over finite-size systems and the connection to the thermodynamic limit. After that, we illustrate pertinent 2D scattering physics and properties of the wave function. We then show energy results for the strong-coupling crossover, in between the Bose-Einstein Condensation (BEC) and Bardeen-Cooper-Schrieffer (BCS) regimes. Our energy results for the BEC-BCS crossover are parametrized to produce an equation of state, which is used to determine Tan's contact. We carry out a detailed comparison with other microscopic results. Finally, we calculate the pairing gap for a range of interaction strengths in the strong coupling regime, following from variationally optimized many-body wave functions.