期刊
COMMUNICATIONS IN THEORETICAL PHYSICS
卷 74, 期 12, 页码 -出版社
IOP Publishing Ltd
DOI: 10.1088/1572-9494/ac921a
关键词
Yang-Gaudin model; quantum integrability; the Bethe ansatz; excitation spectrum
By using an exact Bethe ansatz solution, this study rigorously investigates excitation spectra of the spin-1/2 Fermi gas, discovering different types of excitations such as particle-hole excitations and magnon excitations, and analyzing their properties in depth.
Using an exact Bethe ansatz solution, we rigorously study excitation spectra of the spin-1/2 Fermi gas (called Yang-Gaudin model) with an attractive interaction. Elementary excitations of this model involve particle-hole excitation, hole excitation and adding particles in the Fermi seas of pairs and unpaired fermions. The gapped magnon excitations in the spin sector show a ferromagnetic coupling to the Fermi sea of the single fermions. By numerically and analytically solving the Bethe ansatz equations and the thermodynamic Bethe ansatz equations of this model, we obtain excitation energies for various polarizations in the phase of the Fulde-Ferrell-LarkinOvchinnikov-like state. For a small momentum (long-wavelength limit) and in the strong interaction regime, we analytically obtained their linear dispersions with curvature corrections, effective masses as well as velocities in particle-hole excitations of pairs and unpaired fermions. Such a type of particle-hole excitations display a novel separation of collective motions of bosonic modes within paired and unpaired fermions. Finally, we also discuss magnon excitations in the spin sector and the application of Bragg spectroscopy for testing such separated charge excitation modes of pairs and single fermions.
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