Multi-Ensemble Operation and Lattice Light Shifts in a Yb Optical Lattice Clock

In ‘magic wavelength’ optical lattice clocks (OLCs), non-zero differential polarizabilities between clock states present a fundamental systematic. To characterize these lattice light shifts, clock groups are evaluating higher-order differential polarizability terms, though progress using established techniques is slow due to precision limits arising from laser noise. Here we report a new approach towards evaluating differential polarizabilities, combining dual-ensemble operation in our 1D Yb OLC with differential spectroscopy. By rejecting shared laser noise, we improve measurement precision by an order of magnitude, supporting rapid evaluation of coefficients. With two ensembles, we perform a series of differential experiments, evaluating all differential atomic polarizabilities in a shallow 1D OLC. Our work establishes new techniques for evaluating lattice light shifts while also identifying a new systematic for clocks operating with multiple lattices. Finally, we establish agreement between theory and experiment in the sign and magnitude of the differential polarizability arising from magnetic dipole/electric quadrupole terms, a step towards next-generation accuracy in Yb OLCs.