Cold Bose Gases near Feshbach Resonances

TL;DR

This paper extends the variational method to analyze dilute Bose gases near Feshbach resonances, revealing significant differences from simpler models and suggesting potential stabilization of condensates with negative scattering lengths.

Contribution

It generalizes the variational approach to multi-channel zero-range potentials for Bose gases near Feshbach resonances, providing more accurate energy estimates at high densities.

Findings

Significant differences in energy calculations compared to one-channel models at high densities.

Potential stabilization of uniform condensates with negative scattering length.

Application to Na atoms near a specific Feshbach resonance.

Abstract

The lowest order constrained variational method [Phys. Rev. Lett. 88, 210403 (2002)] has been generalized for a dilute (in the sense that the range of interatomic potential is small compared with inter-particle spacing) uniform gas of bosons near the Feshbach resonance using the multi-channel zero-range potential model. The method has been applied to Na (F=1, m_F=1) atoms near the $B_0=907$G Feshbach resonance. It is shown that at high densities, there are significant differences between our results for the real part of energy per particle and the one-channel zero-range potential approximation. We point out the possibility of stabilization of the uniform con densate for the case of negative scattering length.