Coherent dimer formation near Feshbach resonances in Bose-Einstein condensates

TL;DR

This paper analyzes Bose-Einstein condensate experiments near Feshbach resonances, revealing that the three-body recombination rate depends on pulse rise time, indicating coherent dimer formation.

Contribution

It introduces a mean-field model including dissipation to explain experimental observations and links pulse rise time to coherent dimer formation in BECs.

Findings

Recombination parameter varies with pulse rise time.

Longer pulses align with three-body theory predictions.

Shorter pulses suggest enhanced dimer coherence.

Abstract

The results of a recent experiment with $^{85}$Rb Bose-Einstein condensates are analyzed within the mean-field approximation including dissipation due to three-body recombination. The intensity of the dissipative term is chosen from the three-body theory for large positive scattering lengths. The remaining number of condensed atoms in the experiment, obtained with applied magnetic field pulses, were used to adjust the intensity of the dissipative term. We found that the three-body recombination parameter depends on the pulse rise time; i.e., for longer rise times the values found become consistent with the three-body theory, while for shorter pulses this coefficient is found to be much larger. We interpret this finding as an indication of a coherent formation of dimers.