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A lattice pairing-field approach to ultracold Fermi gases

by Florian Ehmann, Joaquín E. Drut, Jens Braun

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Submission summary

Authors (as registered SciPost users): Jens Braun · Florian Ehmann
Submission information
Preprint Link:  (pdf)
Date accepted: 2024-03-04
Date submitted: 2023-11-21 13:11
Submitted by: Ehmann, Florian
Submitted to: SciPost Physics
Ontological classification
Academic field: Physics
  • Condensed Matter Physics - Theory
  • Condensed Matter Physics - Computational
Approaches: Theoretical, Computational


We develop a pairing-field formalism for ab initio studies of non-relativistic two-component fermions on a $(d\!+\!1)$-dimensional spacetime lattice. More specifically, we focus on theories where the interaction between the two components can be described by the exchange of a corresponding pairing field. The introduction of a pairing field may indeed be convenient for studies of, e.g., the finite-temperature phase structure and critical behavior of, e.g., ultracold atomic Fermi gases. Moreover, such a formalism allows to directly compute the momentum and frequency dependence of the pair propagator, from which the pair-correlation function can be extracted. For a first illustration of the application of our formalism, we compute the density equation of state and the superfluid order parameter for a gas of unpolarized fermions in $(0\!+\!1)$ dimensions by employing the complex Langevin approach to surmount the sign problem.

List of changes

We have included remarks and references in the manuscript to reflect these comments:

1.- We added a reference to arXiv:1403.5680 on page 2 (left column, line 16-20, "We add that our ... see also Ref. [52] for a more general discussion.").

2.- In the right column of page 5, we have slightly adapted the sentence right below Eq. (36) and supplemented it with a footnote (see new footnote #3).

3.- We have adapted our general comments on the sign problem on page 6 (left column, line 4-14, "In this context, it is also ... with, e.g., Ref. [52]"), where also included five new references, see Refs. [52, 78-81].

4.- We have extended our discussion at the end of Subsec. IV.D., where we now comment on potential problems associated with singularities in the drift (see page 10, from line 9 in the left column to line 5 in the right column, "Beyond the expected ... treatment with the complex Langevin method."). Here, we also included six new references, see Refs. [89-94].

Additional change:

We have rephrased the sentence right above Eq. (32) to amend the column breaks on page 5.

Published as SciPost Phys. 16, 091 (2024)

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