Rydberg electrometry for optical lattice clocks

Electrometry is performed using Rydberg states to evaluate the quadratic Stark shift of the 5s²0.16em0ex¹S₀-5s5p0.16em0ex³P₀ clock transition in strontium. By measuring the Stark shift of the highly excited 5s75d0.16em0ex¹D₂ state using electromagnetically induced transparency, we characterize the electric field with sufficient precision to provide tight constraints on the systematic shift to the clock transition. Using the theoretically derived, and experimentally verified, polarizability for this Rydberg state, we can measure the residual field with an uncertainty well below 1 V0.16em0exm^-1. This resolution allows us to constrain the fractional frequency uncertainty of the quadratic Stark shift of the clock transition to 2×10^-20.