# Frequency Shifts due to Stark Effects on a Rb two-photon transition

## TL;DR

This paper provides a detailed calculation and measurement of Stark shifts in a rubidium two-photon transition, crucial for developing stable compact optical atomic clocks, including strategies to mitigate these effects.

## Contribution

It offers the first rigorous calculation of ac-Stark and blackbody radiation shifts for the Rb two-photon transition, with experimental validation and analysis of mitigation techniques.

## Key findings

- Measured ac-Stark shift agrees with calculations
- Identified temperature conditions for zero BBR shift or sensitivity
- Quantified dc-Stark shift and clock sensitivity to alignment variations

## Abstract

The $5S_{1/2}\rightarrow 5D_{5/2}$ two-photon transition in Rb is of interest for the development of a compact optical atomic clock. Here we present a rigorous calculation of the 778.1~nm ac-Stark shift ($2.30(4) \times10^{-13}$(mW/mm$^2$)$^{-1}$) that is in good agreement with our measured value of $2.5(2) \times10^{-13}$(mW/mm$^2$)$^{-1}$. We include a calculation of the temperature-dependent blackbody radiation shift, we predict that the clock could be operated either with zero net BBR shift ($T=495.9(27)$~K) or with zero first-order sensitivity ($T=368.1(14)$~K). Also described is the calculation of the dc-Stark shift of 5.5(1)$\times 10^{-15}$/(V/cm$^2$) as well as clock sensitivities to optical alignment variations in both a cat's eye and flat mirror retro-reflector. Finally, we characterize these Stark effects discussing mitigation techniques necessary to reduce final clock instabilities.