Collective Modes of an Ultracold 6Li-40K Mixture in an Optical Lattice
A low-energy theory of the Nambu-Goldstone excitation spectrum and the corresponding speed of sound of an interacting Fermi mixture of Lithium-6 and Potassium-40 atoms in a two-dimensional optical lattice at finite temperatures with the Fulde-Ferrell order parameter has been formulated. It is assume...
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2015-01-01
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| Series: | Advances in Condensed Matter Physics |
| Online Access: | http://dx.doi.org/10.1155/2015/952852 |
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| author | Z. G. Koinov |
| author_facet | Z. G. Koinov |
| author_sort | Z. G. Koinov |
| collection | DOAJ |
| description | A low-energy theory of the Nambu-Goldstone excitation spectrum and the corresponding speed of sound of an interacting Fermi mixture of Lithium-6 and
Potassium-40 atoms in a two-dimensional optical lattice at finite
temperatures with the Fulde-Ferrell order parameter has been formulated. It is assumed that the two-species interacting Fermi gas is described by the one-band Hubbard Hamiltonian with an attractive on-site interaction. The discussion is restricted to the BCS side of the Feshbach resonance where the Fermi atoms exhibit superfluidity. The quartic on-site interaction is decoupled via a Hubbard-Stratonovich transformation by introducing a four-component boson field which mediates the Hubbard interaction. A functional integral
technique and a Legendre transform are used to give a systematic derivation of the Schwinger-Dyson equations for the generalized single-particle Green’s function and the Bethe-Salpeter equation for the two-particle Green’s function and the associated collective modes. The numerical solution of the Bethe-Salpeter equation in the generalized random phase approximation shows that there exist two distinct sound
velocities in the long-wavelength limit. In addition to low-energy
(Goldstone) mode, the two-species Fermi gas has a superfluid phase revealed by two roton-like minima in the asymmetric collective-mode energy. |
| format | Article |
| id | doaj-art-7ee958bfcc7f46bc971d661cbb82515c |
| institution | Kabale University |
| issn | 1687-8108 1687-8124 |
| language | English |
| publishDate | 2015-01-01 |
| publisher | Wiley |
| record_format | Article |
| series | Advances in Condensed Matter Physics |
| spelling | doaj-art-7ee958bfcc7f46bc971d661cbb82515c2025-02-03T01:25:59ZengWileyAdvances in Condensed Matter Physics1687-81081687-81242015-01-01201510.1155/2015/952852952852Collective Modes of an Ultracold 6Li-40K Mixture in an Optical LatticeZ. G. Koinov0Department of Physics and Astronomy, University of Texas at San Antonio, San Antonio, TX 78249, USAA low-energy theory of the Nambu-Goldstone excitation spectrum and the corresponding speed of sound of an interacting Fermi mixture of Lithium-6 and Potassium-40 atoms in a two-dimensional optical lattice at finite temperatures with the Fulde-Ferrell order parameter has been formulated. It is assumed that the two-species interacting Fermi gas is described by the one-band Hubbard Hamiltonian with an attractive on-site interaction. The discussion is restricted to the BCS side of the Feshbach resonance where the Fermi atoms exhibit superfluidity. The quartic on-site interaction is decoupled via a Hubbard-Stratonovich transformation by introducing a four-component boson field which mediates the Hubbard interaction. A functional integral technique and a Legendre transform are used to give a systematic derivation of the Schwinger-Dyson equations for the generalized single-particle Green’s function and the Bethe-Salpeter equation for the two-particle Green’s function and the associated collective modes. The numerical solution of the Bethe-Salpeter equation in the generalized random phase approximation shows that there exist two distinct sound velocities in the long-wavelength limit. In addition to low-energy (Goldstone) mode, the two-species Fermi gas has a superfluid phase revealed by two roton-like minima in the asymmetric collective-mode energy.http://dx.doi.org/10.1155/2015/952852 |
| spellingShingle | Z. G. Koinov Collective Modes of an Ultracold 6Li-40K Mixture in an Optical Lattice Advances in Condensed Matter Physics |
| title | Collective Modes of an Ultracold 6Li-40K Mixture in an Optical Lattice |
| title_full | Collective Modes of an Ultracold 6Li-40K Mixture in an Optical Lattice |
| title_fullStr | Collective Modes of an Ultracold 6Li-40K Mixture in an Optical Lattice |
| title_full_unstemmed | Collective Modes of an Ultracold 6Li-40K Mixture in an Optical Lattice |
| title_short | Collective Modes of an Ultracold 6Li-40K Mixture in an Optical Lattice |
| title_sort | collective modes of an ultracold 6li 40k mixture in an optical lattice |
| url | http://dx.doi.org/10.1155/2015/952852 |
| work_keys_str_mv | AT zgkoinov collectivemodesofanultracold6li40kmixtureinanopticallattice |