Enhancing the capture velocity of a Dy magneto-optical trap with two-stage slowing

TL;DR

This paper introduces a two-stage slowing technique for Dy magneto-optical traps that significantly increases the MOT loading rate by reducing free-flight losses, achieving over tenfold enhancement in atom capture.

Contribution

It demonstrates, for the first time in Dy, a two-stage slowing scheme that improves MOT loading efficiency by combining Zeeman slowing with a final near-detuned beam stage.

Findings

Over tenfold increase in MOT atom number

Effective reduction of free-flight losses

Enhanced loading rate of Dy MOTs

Abstract

Magneto-optical traps (MOTs) based on the $626\;{\rm nm}$, $136\;{\rm kHz}$-wide intercombination line of Dy, which has an attractively low Doppler temperature of $3.3\;\mu{\rm K}$, have been implemented in a growing number of experiments over the last several years. A challenge in loading these MOTs comes from their low capture velocities. Slowed atomic beams can spread out significantly during free-flight from the Zeeman slower to the MOT position, reducing the fraction of the beam captured by the MOT. Here we apply, for the first time in a Dy experiment, a scheme for enhancing the loading rate of the MOT wherein atoms are Zeeman-slowed to a final velocity larger than the MOT's capture velocity, and then undergo a final stage of slowing by a pair of near-detuned beams addressing the $421\;{\rm nm}$ transition directly in front of the MOT. By reducing the free-flight time of the Zeeman-slowed atomic beam, we greatly enhance the slowed flux delivered to the MOT, leading to more than an order of magnitude enhancement in the final MOT population.