Dimensional crossover and finite-range effects in a quasi-two-dimensional gas of fermionic dimers

TL;DR

This paper studies the properties of ultracold fermionic gases confined in quasi-two-dimensional traps, analyzing finite-range effects and the crossover from three to two dimensions using quantum Monte Carlo simulations and analytical models.

Contribution

It provides a benchmark for effective bosonic models of fermionic dimers and explores the validity of mean-field theories in a strongly interacting quasi-2D regime.

Findings

Finite-range corrections are significant for the equation of state.

The transverse density profile broadens with increasing interaction.

The results validate the effective bosonic description of fermionic dimers.

Abstract

We investigate the ground-state properties of ultracold two-component Fermi gases in the presence of a transverse harmonic potential, focusing on the strongly interacting regime in which pairs of fermions form tightly bound molecules. Using the fixed-node diffusion Monte Carlo method, we calculate the equation of state and density profiles for the full fermionic system, which allows us to address the importance of finite-range corrections arising from the internal fermionic structure of the composite bosons. We interpret the results in terms of a molecular Bose gas in quasi-two-dimensional confinement and compare them with theoretical predictions for a weakly interacting two-dimensional Bose gas, identifying the range of validity of mean-field and beyond-mean-field descriptions. We also develop an analytical theory for the transverse density profile, capturing its broadening with increasing interaction strength. This work provides a benchmark for an effective bosonic description of strongly bound fermionic dimers and offers new insights into the three- to two-dimensional crossover.