BCS-BEC crossover with unequal mass fermions

Abstract

We investigate the crossover from BCS pairing to molecular BEC in an atomic gas with two fermion species with masses $m_\up \ne m_\dn$ tuned through a Feshbach resonance. We present results for the T=0 equation of state as a function of the scattering length including the effects of Gaussian fluctuations about the mean field ground state. We compute the ground state energy as a function of $m_\up/m_\dn$ at unitarity and find excellent agreement with the quantum Monte Carlo result for $m_\up/m_\dn = 6.67$ for a ${}^{40}$K-${}^6$Li mixture. We show that the dimer scattering length in the BEC limit as a function of $m_\up/m_\dn$ compares well with exact four-body results of Petrov {\it et al}. We also derive the condition for trapping frequencies to obtain an unpolarized gas in a harmonic trap.

4 pages, 3 figures

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• Pseudogap and preformed pairs in the imbalanced Fermi gas in two dimensions
• Excitation properties and effects of mass imbalance in the BCS-BEC crossover regime of an ultracold Fermi gas
• Low temperature properties of the fermionic mixtures with mass imbalance in optical lattice
• Fluctuations of imbalanced fermionic superfluids in two dimensions induce continuous quantum phase transitions and non-Fermi liquid behavior
• Hetero pairing and component-dependent pseudogap phenomena in an ultracold Fermi gas with mass imbalance
• Double Degenerate Bose-Fermi Mixture of Strontium and Lithium
• Atom-dimer scattering length for fermions with different masses: analytical study of limiting cases
• Atom-dimer scattering amplitude for fermionic mixtures with different masses: s-wave and p-wave contributions
• Thermal transitions, pseudogap behavior and BCS-BEC crossover in Fermi-Fermi mixtures
• Mass-Imbalanced Superconductivity in Effective Two-Channel Kondo Lattice
• Mass-imbalanced Fermi gases with spin-orbit coupling
• BCS-BEC crossover of the strongly interacting ${}^6$Li-${}^{40}$K mixture