# Dimensional crossover in a strongly interacting ultracold atomic Fermi gas

## TL;DR

This paper investigates the transition from 3D to 2D in a strongly interacting ultracold Fermi gas, analyzing how confinement affects superfluid properties and excitations, with implications for experimental probing.

## Contribution

It provides a theoretical framework for understanding the dimensional crossover in strongly interacting Fermi gases using gaussian pair fluctuation theory.

## Key findings

- Mapped the critical velocity dependence on transverse confinement
- Identified the quasi-2D regime with distinct properties
- Proposed experimental detection via Bragg spectroscopy

## Abstract

We theoretically explore the crossover from three dimensions (3D) to two (2D) in a strongly interacting atomic Fermi superfluid through confining the transverse spatial dimension. Using the gaussian pair fluctuation theory, we determine the zero-temperature equation of state and Landau critical velocity as functions of the spatial extent of the transverse dimension and interaction strength. In the presence of strong interactions, we map out a dimensional crossover diagram from the location of maximum critical velocity, which exhibits distinct dependence on the transverse dimension from 2D to quasi-2D, and to 3D. We calculate the dynamic structure factor to characterize the low-energy excitations of the system and propose that the intermediate quasi-2D regime can be experimentally probed using Bragg spectroscopy.