Ground state energy of spin-1/2 fermions in the unitary limit

TL;DR

This paper provides lattice calculations of the ground state energy for spin-1/2 fermions at the unitary limit, revealing a universal energy ratio in the many-particle limit.

Contribution

It offers new lattice simulation results for the ground state energy of fermions in the unitary regime across various particle numbers, estimating the energy ratio in the large system limit.

Findings

Ground state energy is approximately 0.25 times that of free fermions.

Results are consistent across different particle numbers.

Provides data for future theoretical and experimental comparisons.

Abstract

We present lattice results for the ground state energy of a spin-1/2 fermion system in the unitary limit, where the effective range of the interaction is zero and the scattering length is infinite. We compute the ground state energy for a system of 6, 10, 14, 18, and 22 particles, with equal numbers of up and down spins in a periodic cube. We estimate that in the limit of large number of particles, the ground state energy is 0.25(3) times the ground state energy of the free Fermi system.