Temperature and coupling dependence of the universal contact intensity for an ultracold Fermi gas

TL;DR

This paper investigates how the contact intensity in an ultracold Fermi gas varies with temperature and coupling, revealing significant enhancement near the superfluid transition and aligning well with experimental data.

Contribution

It provides ab initio calculations of the contact intensity across temperature and coupling, highlighting the impact of pairing fluctuations and trap effects.

Findings

Contact intensity peaks near the superfluid transition temperature.

Pairing fluctuations significantly enhance the contact in the pseudogap regime.

Theoretical results agree with experimental measurements across various couplings.

Abstract

Physical properties of an ultracold Fermi gas in the temperature-coupling phase diagram can be characterized by the contact intensity C, which enters the pair-correlation function at short distances and describes how the two-body problem merges into its surrounding. We show that the local order established by pairing fluctuations about the critical temperature Tc of the superfluid transition considerably enhances the contact C in a temperature range where pseudogap phenomena are maximal. Our ab initio results for C in a trap compare well with recently available experimental data over a wide coupling range. An analysis is also provided for the effects of trap averaging on C.