Rb-85 tunable-interaction Bose-Einstein condensate machine

TL;DR

This paper details an experimental setup for creating stable Rb-85 Bose-Einstein condensates with tunable interactions, using sympathetic cooling and Feshbach resonance, suitable for advanced quantum experiments.

Contribution

It introduces a simplified, stable Rb-85 BEC apparatus with tunable interactions, improving upon previous complex setups for dual-species and spinor condensate research.

Findings

Achieved stable Rb-85 BEC with 4 x 10^4 atoms

Demonstrated tunable scattering length using Feshbach resonance

Presented a minimalist design suitable for complex quantum experiments

Abstract

We describe our experimental setup for creating stable Bose-Einstein condensates of Rb-85 with tunable interparticle interactions. We use sympathetic cooling with Rb-87 in two stages, initially in a tight Ioffe-Pritchard magnetic trap and subsequently in a weak, large-volume crossed optical dipole trap, using the 155 G Feshbach resonance to manipulate the elastic and inelastic scattering properties of the Rb-85 atoms. Typical Rb-85 condensates contain 4 x 10^4 atoms with a scattering length of a=+200a_0. Our minimalist apparatus is well-suited to experiments on dual-species and spinor Rb condensates, and has several simplifications over the Rb-85 BEC machine at JILA (Papp, 2007; Papp and Wieman, 2006), which we discuss at the end of this article.