Condensation Energy of a Spin-1/2 Strongly Interacting Fermi Gas

TL;DR

This paper measures the condensation energy of a strongly interacting two-component Fermi gas, providing insights into the superfluid-normal phase transition and comparing experimental results with theoretical models.

Contribution

It presents the first measurement of the condensation energy in a tunable Fermi gas and compares it with advanced theoretical calculations.

Findings

Excellent agreement between measurements and theoretical models

Quantitative relationship between condensation energy and pairing gap

Insights into the BEC-BCS crossover regime

Abstract

We report a measurement of the condensation energy of a two-component Fermi gas with tunable interactions. From the equation of state of the gas, we infer the properties of the normal phase in the zero-temperature limit. By comparing the pressure of the normal phase at T=0 to that of the low-temperature superfluid phase, we deduce the condensation energy, i.e. the energy gain of the system in being in the superfluid rather than normal state. We compare our measurements to a ladder approximation description of the normal phase, and to a fixed node Monte-Carlo approach, finding excellent agreement. We discuss the relationship between condensation energy and pairing gap in the BEC-BCS crossover.