Optical Lattice Induced Light Shifts in an Yb Atomic Clock

TL;DR

This paper experimentally investigates light shifts in a Yb optical lattice clock, determining the magic wavelength, hyperpolarizability effects, and polarization impacts to improve clock accuracy.

Contribution

The study precisely measures the magic wavelength and hyperpolarizability shifts in a Yb lattice clock, demonstrating methods to reduce frequency shift uncertainties below 10^-17.

Findings

Magic wavelength for 174Yb determined at 394799475(35) MHz.

Hyperpolarizability shift estimated at 170(33) mHz.

Circular polarization eliminates certain two-photon resonances.

Abstract

We present an experimental study of the lattice induced light shifts on the 1S_0-3P_0 optical clock transition (v_clock~518 THz) in neutral ytterbium. The ``magic'' frequency, v_magic, for the 174Yb isotope was determined to be 394 799 475(35)MHz, which leads to a first order light shift uncertainty of 0.38 Hz on the 518 THz clock transition. Also investigated were the hyperpolarizability shifts due to the nearby 6s6p 3P_0 - 6s8p 3P_0, 6s8p 3P_2, and 6s5f 3F_2 two-photon resonances at 759.708 nm, 754.23 nm, and 764.95 nm respectively. By tuning the lattice frequency over the two-photon resonances and measuring the corresponding clock transition shifts, the hyperpolarizability shift was estimated to be 170(33) mHz for a linear polarized, 50 uK deep, lattice at the magic wavelength. In addition, we have confirmed that a circularly polarized lattice eliminates the J=0 - J=0 two-photon resonance. These results indicate that the differential polarizability and hyperpolarizability frequency shift uncertainties in a Yb lattice clock could be held to well below 10^-17.