Atom-Number Enhancement by Shielding Atoms from Losses in Strontium Magneto-Optical Traps

TL;DR

This paper introduces a method to increase the number of strontium atoms in magneto-optical traps by using a resonant transition to shield the atoms from losses, effectively doubling the atom count.

Contribution

The authors demonstrate a novel scheme that enhances atom numbers in strontium MOTs by resonantly driving an intercombination line, which is compatible with existing setups and can be extended to other species.

Findings

Achieved a twofold increase in atom number for multiple strontium isotopes.

The experimental results align well with the theoretical model.

The method is easily integrated into current experimental setups.

Abstract

We present a scheme to enhance the atom number in magneto-optical traps of strontium atoms operating on the 461 nm transition. This scheme consists of resonantly driving the $^1$S$_0\to^3$P$_1$ intercombination line at 689 nm, which continuously populates a short-lived reservoir state and, as expected from a theoretical model, partially shields the atomic cloud from losses arising in the 461 nm cooling cycle. We show a factor of two enhancement in the atom number for the bosonic isotopes $^{88}$Sr and $^{84}$Sr, and the fermionic isotope $^{87}$Sr, in good agreement with our model. Our scheme can be applied in the majority of strontium experiments without increasing the experimental complexity of the apparatus, since the employed 689 nm transition is commonly used for further cooling. Our method should thus be beneficial to a broad range of quantum science and technology applications exploiting cold strontium atoms, and could be extended to other atomic species.