Normal state of a polarized fermi gas at unitarity

• Published in: Physical review letters Vol. 97; no. 20; p. 200403
• Main Authors: Lobo, C, Recati, A, Giorgini, S, Stringari, S
• Format: Journal Article
• Language: English
• Published: United States 17-11-2006
• Subjects: BINDING ENERGY; CLASSICAL AND QUANTUM MECHANICS, GENERAL PHYSICS; DIPOLES; EFFECTIVE MASS; EQUATIONS OF STATE; FERMI GAS; INTERACTIONS; MONTE CARLO METHOD; PHASE TRANSFORMATIONS; POLARIZATION; QUASI PARTICLES; SPIN; SUPERFLUIDITY; TRAPPING; UNITARITY
• ISSN: 0031-9007; 1079-7114
• DOI: 10.1103/physrevlett.97.200403

We study the Fermi gas at unitarity and at T=0 by assuming that, at high polarizations, it is a normal Fermi liquid composed of weakly interacting quasiparticles associated with the minority spin atoms. With a quantum Monte Carlo approach we calculate their effective mass and binding energy, as well as the full equation of state of the normal phase as a function of the concentration x=n downward arrow/n upward arrow of minority atoms. We predict a first order phase transition from normal to superfluid at x(c)=0.44 corresponding, in the presence of harmonic trapping, to a critical polarization P(c)=(N upward arrow - N downward arrow/(N upward arrow + N downward arrow)=77%. We calculate the radii and the density profiles in the trap and predict that the frequency of the spin dipole mode will be increased by a factor of 1.23 due to interactions.