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Stability of Bosonic atomic and molecular condensates near a Feshbach resonance

Sourish Basu·Erich J. Mueller
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Abstract

We explore the Bose condensed phases of an atomic gas on the molecular side of a Feshbach resonance. In the absence of atom-molecule and molecule-molecule scattering, we show that the atomic condensate is either a saddle point of the free energy with energy always exceeding that of the molecular condensate, or has a negative compressibility (hence unstable to density fluctuations). Therefore no phase transition occurs between the atomic and molecular condensates. We also show that a repulsive molecule-molecule scattering can stabilize a sufficiently dense atomic condensate, leading to the possibility of a phase transition. We caution that 3-body processes may render this transition unobservable.

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Sourish Basu, Erich J. Mueller. 2006-03-30. Stability of Bosonic atomic and molecular condensates near a Feshbach resonance. https://arxiv.org/abs/cond-mat/0507460

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