Abstract
In a recent paper (2019 Phys. Rev. A 99, 053617), the total number of fermion pairs in a spin-balanced two-component Fermi gas of 6Li atoms was experimentally probed in the normal phase above the superfluid critical temperature, in order to investigate the sectors of pseudogap and preformed-pair in the temperature–coupling phase diagram. Here, we present a theoretical account of these experimental results in terms of an ab initio self-consistent t-matrix calculation, which emphasizes the role of the pair-correlation function between opposite-spin fermions at equilibrium. Good agreement is found between the available experimental data and the theoretical results obtained with no adjustable parameter.
Highlights
Preformed pairs are meant to be bound states which form above the critical temperature of a fermionic superfluid [1, 2]
Preformed pairs were recently studied in an experiment with a spin-balanced two-component Fermi gas of 6Li in the normal phase [4], where the number of fermion pairs Np was determined by converting all atom pairs to tightly-bound diatomic molecules which afterward were detected
A preliminary theoretical account of the pairing fractions was already presented in reference [4], which was obtained by a statistical model of non-interacting atoms and molecules at equilibrium [5, 6] as well as by an ab initio diagrammatic t-matrix approach [7]
Summary
M Pini1, P Pieri1,2 , M Jager3, J Hecker Denschlag3 and G Calvanese Strinati1,2,4,5 Original content from this work may be used under the terms of the Creative Commons Attribution 4.0 licence. Any further distribution of this work must maintain attribution to the author(s) and the title of the work, journal citation and DOI.
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