Bi-color atomic beam slower and magnetic field compensation for ultracold gases

TL;DR

This paper introduces a bi-color atomic beam slower and a magnetic field compensation system that significantly enhances cold atom production and stability in ultracold gases experiments.

Contribution

It presents a novel bi-color slowing scheme for strontium atoms and a 3-axis active magnetic field feedback system for improved MOT performance.

Findings

Increased atom number in MOT by eleven times.

Effective suppression of magnetic field fluctuations.

Enhanced stability of ultracold atom experiments.

Abstract

Transversely loaded bidimensional-magneto-optical-traps (2D-MOT) have been recently developed as high flux sources for cold strontium atoms to realize a new generation of compact experimental setups. Here, we discuss on the implementation of a cross-polarized bi-color slower for a strontium atomic beam improving the 2D-MOT loading, and increasing the number of atoms in a final MOT by eleven times. Our slowing scheme addresses simultaneously two excited Zeeman substates of the 88Sr 1S0->1P1 transition at 461 nm. We also realized a 3-axis active feedback control of the magnetic field down to the microgauss regime. Such a compensation is performed thanks to a network of eight magnetic field probes arranged in a cuboid configuration around the atomic cold sample, and a pair of coils in Helmholtz configuration along each of three Cartesian directions. Our active feedback is capable of efficiently suppressing most of the magnetically-induced position fluctuations of the 689~nm intercombination-line MOT.