Atom-molecule coherence in a one-dimensional system.
We study a model of one-dimensional fermionic atoms with a narrow Feshbach resonance that allows them to bind in pairs to form bosonic molecules. We show that at low energy, a coherence develops between the molecule and fermion Luttinger liquids. At the same time, a gap opens in the spin excitation spectrum. The coherence implies that the order parameters for the molecular Bose-Einstein condensation and the atomic BCS pairing become identical. Moreover, both bosonic and fermionic charge density wave correlations decay exponentially, in contrast with a usual Luttinger liquid. We exhibit a Luther-Emery point where the systems can be described in terms of noninteracting pseudofermions. At this point we discuss the threshold behavior of density-density response functions.
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Dipartimento di Fisica E. R. Caianiello and Laboratorio Regionale SUPERMAT C. N. R., Università degli Studi di Salerno, Via S. Allende, I-84081 Baronissi (Sa), Italy.
Orignac
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