The universal equation of state of a unitary fermionic gas

TL;DR

This paper proposes a universal equation of state for a unitary fermionic gas based on a two-body ansatz, achieving parameter-free agreement with experimental data and enabling calculations of more sensitive quantities.

Contribution

It introduces a novel, parameter-free equation of state for a unitary fermionic gas using a two-body ansatz, aligning well with recent experimental measurements.

Findings

Excellent agreement with ENS group measurements for homogeneous and trapped gases

Successful calculation of sensitive quantities measured by MIT group

Highlights the special role of two-body bonds at unitarity

Abstract

It is suggested that for a fermi gas at unitarity, the two-body bond plays a special role. We propose an equation of state using an ansatz relating the interaction part of the $l$-body cluster to its two-body counterpart. This allows a parameter-free comparison with the recently measured equation of state by the ENS group. The agreement between the two over a range of fugacity ($z<5$ for a homogeneous gas, and $z<10$ for the trapped gas) leads us to perform the calculations of more sensitive quantities measured recently by the MIT group.