Bosonic characters of atomic Cooper pairs across resonance

Abstract

We study the two-particle wave function of paired atoms in a Fermi gas with tunable interaction strengths controlled by Feshbach resonance. The Cooper pair wave function is examined for its bosonic characters, which is quantified by the correction of Bose enhancement factor associated with the creation and annihilation composite particle operators. An example is given for a three-dimensional uniform gas. Two definitions of Cooper pair wave function are examined. One of which is chosen to reflect the off-diagonal long range order (ODLRO). Another one corresponds to a pair projection of a BCS state. On the side with negative scattering length, we found that paired atoms described by ODLRO are more bosonic than the pair projected definition. It is also found that at $(k_{F}a{)}^{-1}\ge 1$, both definitions give similar results, where more than 90% of the atoms occupy the corresponding molecular condensates.

6 pages, 4 figures, accepted by PRA

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• Fermionic Superfluidity with Imbalanced Spin Populations and the Quantum Phase Transition to the Normal State
• Collective excitations of a degenerate gas at the BEC-BCS crossover
• Condensate Fraction of a Fermi Gas in the BCS-BEC Crossover
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Cited by in corpus (14)

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• Entanglement and Composite Bosons
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• "Commutator formalism" for pairs correlated through Schmidt decomposition as used in Quantum Information
• Entanglement between two spatially separated ultracold interacting Fermi gases
• How bosonic is a pair of fermions?
• Composite-boson approach to molecular Bose-Einstein condensates in mixtures of ultracold Fermi gases
• Fermionic versus bosonic behavior of confined Wigner molecules
• Quantum information approach to Bose-Einstein condensation of composite bosons
• Statistical signatures of states orthogonal to the Fock-state ladder of composite bosons
• On the description of composite bosons in discrete models
• On dynamical stability of composite quantum particles: when entanglement is enough and when interaction is needed
• Nonlocal bunching of composite bosons
• Conserved operators and exact conditions for pair condensation