Effective theory for weakly coupled one-dimensional imbalanced Fermi gas

Ann Sophie C. Rittner, Yean-an Liao, Tobias Paprotta +3 more

V. Ya. Krivnov, А. А. Овчинников

K. B. Gubbels, Henk T. C. Stoof

We formulate a Wilsonian renormalization group theory for the imbalanced Fermi gas. The theory is able to recover quantitatively well-established results in both the weak-coupling and the strong-coupling (unitarity) limits. We determine for the latter case the line of second-order phase transitions of the imbalanced Fermi gas and, in particular, the location of the tricritical point. We obtain good agreement with the recent experiments of Y. Shin et al. [Nature (London) 451, 689 (2008)10.1038/nature06473].

Yean-an Liao, Ann Sophie C. Rittner, Tobias Paprotta +5 more

Randall G. Hulet

Shovan Dutta, Erich J. Mueller

We model the one-dimensional (1D) to three-dimensional (3D) crossover in a cylindrically trapped Fermi gas with attractive interactions and spin imbalance. We calculate the mean-field phase diagram and study the relative stability of exotic superfluid phases as a function of interaction strength and temperature. For weak interactions and low density, we find 1D-like behavior, which repeats as a function of the chemical potential as new channels open. For strong interactions, mixing of single-particle levels gives 3D-like behavior at all densities. Furthermore, we map the system to an effective 1D model, finding significant density dependence of the effective 1D scattering length.