Light Assisted Collisional Loss in a $^{85/87}$Rb Ultracold Optical Trap

TL;DR

This study investigates light-assisted collisional losses in a dual isotope rubidium optical trap, revealing isotope-dependent collision rates and saturation effects that impact trap loading efficiency.

Contribution

It provides new insights into isotope-specific collision dynamics and the influence of hyperfine structure on loss rates in ultracold rubidium traps.

Findings

Different loss rates observed for various excited state potentials.

Some collisional channels' loss rates saturate at specific intensities.

Hyperfine structure significantly affects collision rates.

Abstract

We have studied hetero- and homonuclear excited state/ground state collisions by loading both $^{85}$Rb and $^{87}$Rb into a far off resonant trap (FORT). Because of the relatively weak confinement of the FORT, we expect the hyperfine structure of the different isotopes to play a crucial role in the collision rates. This dependence on hyperfine structure allows us to measure collisions associated with long range interatomic potentials of different structure: such as long and short ranged; or such as purely attractive, purely repulsive, or mixed attractive and repulsive. We observe significantly different loss rates for different excited state potentials. Additionally, we observe that some collisional channels' loss rates are saturated at our operating intensities (~15 mW/cm$^{2}$). These losses are important limitations in loading dual isotope optical traps.