Lattice Induced Frequency Shifts in Sr Optical Lattice Clocks at the $10^{-17}$ Level

TL;DR

This paper provides a detailed experimental analysis of frequency shifts in Sr optical lattice clocks, achieving high precision measurements that set new bounds on various perturbations and confirm clock accuracy at the 10^{-17} level.

Contribution

It presents the first experimental upper bounds on magnetic dipole and electric quadrupole shift contributions, and reports the first observation of vector and tensor shifts in a lattice clock.

Findings

Lattice related shifts are below 10^{-17} accuracy.

First experimental upper bound on M1 and E2 shifts.

First observation of vector and tensor shifts.

Abstract

We present a comprehensive study of the frequency shifts associated with the lattice potential for a Sr lattice clock. By comparing two such clocks with a frequency stability reaching $5\times 10^{-17}$ after a one hour integration time, and varying the lattice depth up to $U_0=900 \, E_r$ with $E_r$ being the recoil energy, we evaluate lattice related shifts with an unprecedented accuracy. We put the first experimental upper bound on the recently predicted frequency shift due to the magnetic dipole (M1) and electric quadrupole (E2) interactions. This upper bound is significantly smaller than the theoretical upper limit. We also give a new upper limit on the effect of hyperpolarizability with an improvement by more than one order of magnitude. Finally, we report the first observation of the vector and tensor shifts in a lattice clock. Combining these measurements, we show that all known lattice related perturbation will not affect the clock accuracy down to the $10^{-17}$ level, even for very deep lattices, up to $U_0=150\,E_r$.