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arXiv:physics/0505023

Radiative Transfer and Atom Transport

Carsten Henkel

Published May 3, 2005• 2 citations
arXivHTMLPDF

Abstract

The report deals with classical and quantum descriptions of particles that interact with smooth random potentials, for example ultracold atoms in the dipole potential of an optical speckle pattern. In addition, a discussion of the link between Radiative Transfer theory and the underlying coherence theory of wave optics is presented. The Radiative Transfer Equation is shown to emerge as a limiting case of the Bethe-Salpeter Equation, and some next-order corrections are discussed.

DOI
10.48550/arxiv.physics/0505023

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The report deals with classical and quantum descriptions of particles that interact with smooth random potentials, for example ultracold atoms in the dipole potential of an optical speckle pattern. In addition, a discussion of the link between Radiative Transfer theory and the underlying coherence theory of wave optics is presented. The Radiative Transfer Equation is shown to emerge as a limiting case of the Bethe-Salpeter Equation, and some next-order corrections are discussed.
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Low-energy theory of the Nambu-Goldstone modes of an ultracold 6Li−^6Li-6Li− 40K^{40}K40K 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 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 the long-wavelength mode (Goldstone mode), the two-species Fermi gas has a superfluid phase revealed by two rotonlike minima in the asymmetric collective-mode energy.
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