Controlling Condensate Collapse and Expansion with an Optical Feshbach Resonance

TL;DR

This paper demonstrates precise control over the collapse and expansion of an 88Sr Bose-Einstein condensate using an optical Feshbach resonance, enabling tunable interactions via laser detuning.

Contribution

It introduces a method to manipulate BEC dynamics with optical Feshbach resonance near the 1S0-3P1 transition, showing real-time control of scattering length.

Findings

Blue detuning increases interaction energy and accelerates expansion.

Red detuning induces collapse of the condensate.

Changes in scattering length are monitored via condensate size after expansion.

Abstract

We demonstrate control of the collapse and expansion of an 88Sr Bose-Einstein condensate using an optical Feshbach resonance (OFR) near the 1S0-3P1 intercombination transition at 689 nm. Significant changes in dynamics are caused by modifications of scattering length by up to +- ?10a_bg, where the background scattering length of 88Sr is a_bg = -2a0 (1a0 = 0.053 nm). Changes in scattering length are monitored through changes in the size of the condensate after a time-of-flight measurement. Because the background scattering length is close to zero, blue detuning of the OFR laser with respect to a photoassociative resonance leads to increased interaction energy and a faster condensate expansion, whereas red detuning triggers a collapse of the condensate. The results are modeled with the time-dependent nonlinear Gross-Pitaevskii equation.