The Trapped Polarized Fermi Gas at Unitarity

TL;DR

This paper investigates the energy properties of polarized Fermi gases at unitarity under harmonic confinement, revealing a universal energy curve that applies even to small systems, using advanced Monte Carlo simulations.

Contribution

It introduces a simple parameterization of the universal energy curve for trapped polarized Fermi gases at unitarity, connecting it to the bulk equation of state.

Findings

Energy of the normal state follows a universal curve.

Universal curve applies to small systems.

Parameterization relates trapped system to bulk properties.

Abstract

We consider population-imbalanced two-component Fermi gases under external harmonic confinement interacting through short-range two-body potentials with diverging s-wave scattering length. Using the fixed-node diffusion Monte Carlo method, the energies of the "normal state" are determined as functions of the population-imbalance and the number of particles. The energies of the trapped system follow, to a good approximation, a universal curve even for fairly small systems. A simple parameterization of the universal curve is presented and related to the equation of state of the bulk system.