Phase diagram and deformed phase separation for a trapped Fermi gas with population imbalance and BCS pairing interaction

• Published in: The European physical journal. B, Condensed matter physics Condensed matter physics, 2010-11, Vol.78 (1), p.43-49
• Main Authors: Ying, Z.-J., Cuoco, M., Noce, C., Zhou, H.-Q.
• Format: Article
• Language: English
• Subjects: Classical and quantum physics: mechanics and fields; Complex Systems; Condensed Matter Physics; Exact sciences and technology; Fluid- and Aerodynamics; Matter waves; Physics; Physics and Astronomy; Solid State Physics
• ISSN: 1434-6028; 1434-6036
• DOI: 10.1140/epjb/e2010-10515-0

We study the phase separated state of an ultracold atomic Fermi gas confined in a three-dimensional quantum harmonic trap with a BCS pairing interaction. Examining various finite-temperature phase diagrams, we investigate the interplay between the filling of the quantum trap energy levels and the pairing energy. We find that a low (high) filling leads to a large (small) critical population imbalance for the superfluid/normal transition, together with a fully (partially) polarized normal part. We also show that the decrease of the density leads to a changeover of the shape of the superfluid core from an equipotential form to a deformed one. Moreover, we clarify the intrinsic mechanisms that lead to the deformation, providing a unified scenario for phase separation and deformation in a trapped Fermi gas, allowing for a possible interpretation of the apparently controversial experimental findings.