In-Situ Differential-Light-Shift Cancellation for Trapped-Atom Clocks

TL;DR

The paper presents an in-situ method to cancel differential light shifts in trapped-atom clocks by using multiple ensembles at different trap intensities and Ramsey spectroscopy, improving clock stability.

Contribution

A novel in-situ technique for DLS cancellation that does not require magic wavelengths or species-specific schemes, enhancing accuracy of trapped-atom clocks.

Findings

Effective DLS cancellation demonstrated in Rb atom traps.

Frequency remains stable despite trap power fluctuations.

Method is general and applicable to other systematic shifts.

Abstract

Differential light shifts (DLS) induced by optical trapping fields fundamentally limit the stability and accuracy of trapped-atom microwave clocks. We demonstrate an in-situ method to cancel DLS by simultaneously interrogating multiple spatially separated atomic ensembles at different trap intensities generated from a common light source. By operating the ensembles at set intensity ratios and performing Ramsey spectroscopy, the intensity-dependent frequency shifts are measured within each experimental cycle and extrapolated to the zero-intensity limit. This approach effectively enables shot-to-shot determination of a DLS-free frequency without requiring magic wavelengths or species-specific cancellation schemes. We validate the method for Rb atoms trapped in time-averaged potentials by introducing controlled variations of the total trap power and show that the extrapolated frequency remains insensitive to these fluctuations. The technique is general and can be extended to other systematic shifts, providing a scalable route toward improved stability and accuracy in compact trapped-atom clocks and related quantum sensors relying on optical dipole traps