Pseudo-gap pairing in ultracold Fermi atoms

TL;DR

This paper investigates pseudogap pairing in strongly interacting ultracold Fermi gases, using a quantum cluster expansion to calculate dynamical properties, and finds agreement with experimental spectral measurements indicating pseudogap phenomena.

Contribution

It introduces a quantum cluster expansion method to compute dynamical properties of strongly correlated Fermi gases, revealing pseudogap pairing consistent with recent experiments.

Findings

Spectral functions show pseudogap features in the strongly interacting regime.

Calculations agree with recent rf and Bragg spectroscopy measurements.

Demonstrates the presence of pseudogap pairing in ultracold Fermi gases.

Abstract

The crossover from a BEC (Bose-Einstein condensation) to a BCS (Bardeen-Cooper-Schrieffer) superfluid in dilute gases of ultracold Fermi atoms creates an ideal environment to enrich our knowledge of strongly correlated many-body systems. These experiments are relevant to a wide range of fields from condensed matter to astrophysics. The nature of pairing in strongly interacting Fermi gases can be readily studied, thus aiding our understanding of related problems in high-T_{c} superconductors, whose mechanism is still under debate. These are not well-understood due to the large interaction parameter. Here, we calculate the dynamical properties of a normal, trapped, and strongly correlated Fermi gas, by developing a quantum cluster expansion. In ultra-cold atomic physics one can measure the elementary excitations, using rf or Bragg spectroscopy. Our calculations for the single-particle spectral function agree with the recent measurements, and clearly demonstrate pseudogap pairing in the strongly interacting regime.