Enhanced Atom Capture via Multi-Frequency Magneto-Optical Trapping

TL;DR

Using multiple closely spaced optical frequencies in a magneto-optical trap significantly increases atom number and loading rate, enhancing quantum sensing and fundamental physics experiments.

Contribution

Demonstrated that multi-frequency cooling doubles atom number and quadruples loading rate without additional slowing techniques, offering a scalable approach for high-flux cold-atom sources.

Findings

Doubling of steady state atom number.

Loading rate increased by up to a factor of 4.

Numerical simulations predict larger gains for bigger traps.

Abstract

Magneto-optical traps are central to atomic and molecular quantum technologies and precision tests of fundamental physics, where both sensitivity and bandwidth scale strongly with atom number and loading rate. We demonstrate that employing multiple, closely spaced optical frequency components in the cooling light of a $^{87}$Rb magneto-optical trap -- without utilizing any additional slowing techniques -- can double the steady state atom number and increase the loading rate by up to a factor of 4, compared to a conventional single-frequency implementation. Subsequently, we capture up to $1.0(1)\times10^{10}$ atoms with a loading rate of up to $1.3(2)\times 10^{11}\,\mathrm{atoms\,s^{-1}}$ from a thermal background. Numerical simulations reproduce the observed trends and predict substantially larger gains for increased trap sizes beyond our experimental bounds. By re-examining earlier studies of multi-frequency atom capture in the context of modern experimental hardware and emerging applications, we show that previously identified limitations can be avoided and establish multi-frequency cooling as a practical and scalable route to high-flux cold-atom sources. These results have immediate applications in portable atom-based quantum sensing, where higher bandwidth and precision can be achieved without forgoing compactness, and in atom-interferometric tests of fundamental physics, which benefit from access to larger-mass quantum systems.