Radio-Frequency Spectroscopy and the Dimensional Crossover in Interacting Spin-Polarized Fermi Gases

TL;DR

This paper investigates how radio-frequency spectroscopy reveals the dimensional crossover in spin-polarized Fermi gases confined in anisotropic traps, highlighting the role of emergent s-wave interactions in p-wave systems.

Contribution

It provides a theoretical analysis of RF spectroscopy signatures during 1D-to-3D and 2D-to-3D crossovers, including the effects of strong harmonic confinement and emergent interactions.

Findings

RF spectroscopy captures the dimensional crossover signatures.

Emergent s-wave interactions are crucial for understanding p-wave Fermi gases.

The two-body T-matrix approach accurately models the bound states and transfer rates.

Abstract

Low-dimensional ultracold gases are created in the laboratory by confining three-dimensional (3D) gases inside highly anisotropic trapping potentials. Such trap geometries not only provide access to simulating one-dimensional (1D) and two-dimensional (2D) physics, but also can be used to study how the system crosses over towards a 3D system in the limit of weak confinement. In this work, we study the signature in radio-frequency (RF) spectroscopy for both the 1D-to-3D and the 2D-to-3D crossovers, in spin-polarized Fermi gases. We solve the two-body scattering T-matrix in the presence of strong harmonic confinement and use it to evaluate the two-body bound state and the RF spectroscopy transfer rate in the high frequency limit, covering both the quasi-low-dimensional and 3D limits. We find that in order to understand the dimensional crossover for spin-polarized Fermi gases with p-wave interactions, one needs to take into account an emergent s-wave interaction.