Faraday-shielded, DC Stark-free optical lattice clock

TL;DR

This paper demonstrates that Faraday shielding effectively suppresses DC Stark shifts in an ytterbium optical lattice clock, achieving a measurement constraint at the 10^-20 level and addressing potential error sources.

Contribution

The study introduces in-vacuum Faraday shielding combined with experimental validation to eliminate DC Stark shifts in optical lattice clocks, providing a practical and effective solution.

Findings

DC Stark shift constrained at 10^-20 level

Faraday shielding effectively suppresses stray electric fields

Field gradients can cause measurement errors in Stark shift assessments

Abstract

We demonstrate the absence of a DC Stark shift in an ytterbium optical lattice clock. Stray electric fields are suppressed through the introduction of an in-vacuum Faraday shield. Still, the effectiveness of the shielding must be experimentally assessed. Such diagnostics are accomplished by applying high voltage to six electrodes, which are grounded in normal operation to form part of the Faraday shield. Our measurements place a constraint on the DC Stark shift at the $10^{-20}$ level, in units of the clock frequency. Moreover, we discuss a potential source of error in strategies to precisely measure or cancel non-zero DC Stark shifts, attributed to field gradients coupled with the finite spatial extent of the lattice-trapped atoms. With this consideration, we find that Faraday shielding, complemented with experimental validation, provides both a practically appealing and effective solution to the problem of DC Stark shifts in optical lattice clocks.