Direct loading of a large Yb MOT on the $^{1}S_{0} \rightarrow \, ^{3}P_{1}$ transition

TL;DR

This paper introduces a robust laser frequency stabilization method that allows direct loading of over 10^9 ytterbium atoms into a magneto-optical trap on the narrow $^{1}S_{0} ightarrow ^{3}P_{1}$ transition, bypassing the usual first-stage MOT.

Contribution

The authors develop a simple atomic beam setup for high signal-to-noise spectroscopy enabling stable laser locking directly on the narrow transition for efficient atom trapping.

Findings

Achieved stable loading of over 10^9 Yb atoms into the MOT.

Demonstrated high-precision measurements of gravitational sag.

Validated the technique's stability and accuracy through experimental data.

Abstract

We report a robust technique for laser frequency stabilisation that enables the reproducible loading of in excess of 10$^{9}$ Yb atoms from a Zeeman slower directly into a magneto-optical trap (MOT) operating on the $^{1}S_{0} \rightarrow \, ^{3}P_{1}$ transition, without the need for a first stage MOT on the $^{1}S_{0} \rightarrow \, ^{1}P_{1}$ transition. We use a simple atomic beam apparatus to generate narrow fluorescence signals on both the 399 nm $^{1}S_{0} \rightarrow \, ^{1}P_{1}$ transition used for the Zeeman slower and the 556 nm $^{1}S_{0} \rightarrow \, ^{3}P_{1}$ transition. We present in detail the methods for obtaining spectra with a high signal-to-noise ratio and demonstrate error signals suitable for robust frequency stabilisation. Finally we demonstrate the stability and precision of our technique through sensitive measurements of the gravitational sag of the Yb MOT as a function of the intensity of the laser cooling beams, which are in good agreement with theory. These results will be important for efficient loading of the atoms into an optical dipole trap.