Bose-Einstein condensation of heteronuclear bound states formed in a Fermi gas of two atomic species: microscopic approach

Abstract

We study a many-body system of interacting fermionic atoms of two species that are in thermodynamic equilibrium with their condensed heteronuclear bound states (molecules). In order to describe such an equilibrium state, we use a microscopic approach that involves the Bogoliubov model for a weakly interacting Bose gas and approximate formulation of the second quantization method in the presence of bound states of particles elaborated earlier by the authors. This microscopic approach is valid at low temperatures, when the average kinetic energy of all the components in the system is small in comparison with the bound state energy. The coupled equations, which relate the chemical potentials of fermionic components and molecular condensate density, are obtained within the proposed theory. At zero temperature, these equations are analyzed both analytically and numerically, attracting the relevant experimental data. We find the conditions at which a condensate of heteronuclear molecules coexists in equilibrium with degenerate components of a Fermi gas. The ground state energy and single-particle excitation spectrum are found. The boundaries of the applicability of the developed microscopic approach are analyzed.

revised version: 24 pages, 2 figures, typos corrected, explanations added, figures re-plotted, published version

References in corpus (17)

• Many-Body Physics with Ultracold Gases
• Theory of ultracold Fermi gases
• Weakly bound dimers of fermionic atoms
• Resonantly-paired fermionic superfluids
• Pure Gas of Optically Trapped Molecules Created from Fermionic Atoms
• Ultracold heteronuclear molecules in a 3D optical lattice
• Formation of Quantum-Degenerate Sodium Molecules
• BEC-BCS crossover, phase transitions and phase separation in polarized resonantly-paired superfluids
• Ultracold Heteronuclear Fermi-Fermi Molecules
• Observation of Heteronuclear Feshbach Molecules from a ${}^{85}$Rb - ${}^{87}$Rb gas
• Nonequilibrium dynamics and thermodynamics of a degenerate Fermi gas across a Feshbach resonance
• Diatomic molecules in ultracold Fermi gases - Novel composite bosons
• Association of ultracold double-species bosonic molecules
• Superfluidity and phase transitions in a resonant Bose gas
• Production of optically trapped ${}^{87}$RbCs Feshbach molecules
• Photoassociation of ultracold LiRb* molecules: observation of high efficiency and unitarity-limited rate saturation
• Green-function method in the theory of ultraslow electromagnetic waves in an ideal gas with Bose-Einstein condensates

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