Heating and atom loss during upward ramps of Feshbach resonance levels in Bose-Einstein condensates

TL;DR

This paper investigates atom loss and heating in Bose-Einstein condensates during upward Feshbach resonance ramps, comparing various theoretical models and experimental data to understand the underlying physics.

Contribution

It provides a comparative analysis of different theoretical approaches predicting atom loss during Feshbach resonance ramps in BECs, highlighting their agreement despite microscopic differences.

Findings

All models predict similar atom loss for linear ramps.

Atom loss is insensitive to microscopic physics details.

Theoretical predictions agree with recent experiments on 23Na and 85Rb.

Abstract

The production of pairs of fast atoms leads to a pronounced loss of atoms during upward ramps of Feshbach resonance levels in dilute Bose-Einstein condensates. We provide comparative studies on the formation of these bursts of atoms containing the physical predictions of several theoretical approaches at different levels of approximation. We show that despite their very different description of the microscopic binary physics during the passage of a Feshbach resonance, all approaches lead to virtually the same prediction on the total loss of condensate atoms, provided that the ramp of the magnetic field strength is purely linear. We give the reasons for this remarkable insensitivity of the remnant condensate fraction to the microscopic physical processes and compare the theoretical predictions with recent Feshbach resonance crossing experiments on 23Na and 85Rb.