Miscibility in a degenerate fermionic mixture induced by linear coupling
- Instituto de Fisica Teorica, UNESP-Sao Paulo State University, 01.405-900 Sao Paulo, Sao Paulo (Brazil)
We consider a one-dimensional mean-field-hydrodynamic model of a two-component degenerate Fermi gas in an external trap, each component representing a spin state of the same atom. We demonstrate that the interconversion between them (linear coupling), imposed by a resonant electromagnetic wave, transforms the immiscible binary gas into a miscible state, if the coupling constant, {kappa}, exceeds a critical value, {kappa}{sub cr}. The effect is predicted in a variational approximation, and confirmed by numerical solutions. Unlike the recently studied model of a binary Bose-Einstein condensate with the linear coupling, the components in the immiscible phase of the binary fermion mixture never fill two separated domains with a wall between them, but rather form antilocked ({pi}-phase-shifted) density waves. Another difference from the bosonic mixture is spontaneous breaking of symmetry between the two components in terms of the numbers of atoms in them, N{sub 1} and N{sub 2}. The latter effect is characterized by the parameter {nu}{identical_to}(N{sub 1}-N{sub 2})/(N{sub 1}+N{sub 2}) (only N{sub 1}+N{sub 2} is a conserved quantity), the onset of miscibility at {kappa}{>=}{kappa}{sub cr} meaning a transition to {nu}{identical_to}0. At {kappa}<{kappa}{sub cr}, {nu} features damped oscillations as a function of {kappa}. We also briefly consider an asymmetric model, with a chemical-potential difference between the two components. The relation between the imbalance in the spin population, induced by the linear coupling, and the developing spatial structure resembles the known Larkin-Ovchinnikov-Fulde-Ferrell states in the Fermi mixture. Dynamical states, when {kappa} is suddenly switched from zero to a value exceeding {kappa}{sub cr}, are considered too. In the latter case, the system features oscillatory relaxation to the mixed state.
- OSTI ID:
- 20974782
- Journal Information:
- Physical Review. A, Vol. 74, Issue 5; Other Information: DOI: 10.1103/PhysRevA.74.053620; (c) 2006 The American Physical Society; Country of input: International Atomic Energy Agency (IAEA); ISSN 1050-2947
- Country of Publication:
- United States
- Language:
- English
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Related Subjects
APPROXIMATIONS
ASYMMETRY
BOSE-EINSTEIN CONDENSATION
COUPLING CONSTANTS
ELECTROMAGNETIC RADIATION
FERMI GAS
FERMIONS
HYDRODYNAMIC MODEL
HYDRODYNAMICS
MEAN-FIELD THEORY
MIXED STATE
ONE-DIMENSIONAL CALCULATIONS
PHASE SHIFT
SPIN
SYMMETRY BREAKING
VARIATIONAL METHODS