Thermodynamics of Trapped Imbalanced Fermi Gases at Unitarity
Abstract
We present a theory for the low-temperature properties of a resonantly interacting Fermi mixture in a trap, that goes beyond the local-density approximation. The theory corresponds essentially to a Landau-Ginzburg-like approach that includes self-energy effects to account for the strong interactions at unitarity. We show diagrammatically how these self-energy effects arise from fluctuations in the superfluid order parameter. Gradient terms of the order parameter are included to account for inhomogeneities. This approach incorporates the state-of-the-art knowledge of the homogeneous mixture with a population imbalance exactly and gives good agreement with the experimental density profiles of Shin et al. (Nature 451:689 (2008)). This allows us to calculate the universal surface tension of the interface between the equal-density superfluid and the partially polarized normal state of the mixture. We also discuss the possibility of a metastable state to explain the deformation of the superfluid core that is seen in the experiment of Partridge et al. (Science 311:503 (2006)).
- Publication:
-
Lecture Notes in Physics, Berlin Springer Verlag
- Pub Date:
- 2012
- DOI:
- 10.1007/978-3-642-21978-8_13
- arXiv:
- arXiv:1102.3320
- Bibcode:
- 2012LNP...836..477D
- Keywords:
-
- Condensed Matter - Quantum Gases
- E-Print:
- 26 pages, 7 figures, contribution to Lecture Notes in Physics "BCS-BEC crossover and the Unitary Fermi Gas" edited by W. Zwerger