Ratchet Loading and Multi-Ensemble Operation in an Optical Lattice Clock

TL;DR

This paper introduces a method for programmable spatial control of ultra-cold atoms in an optical lattice, enabling multi-ensemble operation and improved frequency stability for optical lattice clocks.

Contribution

It presents a novel technique for loading and manipulating multiple atomic ensembles in an optical lattice, enhancing clock stability and enabling advanced spectroscopic protocols.

Findings

Achieved uniform atomic density over 5 mm in an optical lattice clock.

Demonstrated multi-ensemble clock operation with independently addressable ensembles.

Measured a fractional frequency instability of 2.4×10⁻¹⁷ at one second between ensembles.

Abstract

We demonstrate programmable control over the spatial distribution of ultra-cold atoms confined in an optical lattice. The control is facilitated through a combination of spatial manipulation of the magneto-optical trap and atomic population shelving to a metastable state. We first employ the technique to load an extended (5 mm) atomic sample with uniform density in an optical lattice clock, reducing atomic interactions and realizing remarkable frequency homogeneity across the atomic cloud. We also prepare multiple spatially separated atomic ensembles and realize multi-ensemble clock operation within the standard one-dimensional (1D) optical lattice clock architecture. Leveraging this technique, we prepare two oppositely spin-polarized ensembles that are independently addressable, offering a platform for implementing spectroscopic protocols for enhanced tracking of local oscillator phase. Finally, we demonstrate a relative fractional frequency instability at one second of $2.4(1) \times10^{-17}$ between two ensembles, useful for characterization of intra-lattice differential systematics.