Limits on Violations of Lorentz Symmetry and the Einstein Equivalence Principle using Radio-Frequency Spectroscopy of Atomic Dysprosium

Understand

We report a joint test of local Lorentz invariance and the Einstein equivalence principle for electrons, using long-term measurements of the transition frequency between two nearly degenerate states of atomic dysprosium.

• We present many-body calculations which demonstrate that the energy splitting of these states is particularly sensitive to violations of both special and general relativity.
• We limit Lorentz violation for electrons at the level of $10^{-17}$, matching or improving the best laboratory and astrophysical limits by up to a factor of 10, and improve bounds on gravitational redshift anomalies for electrons by 2 orders of magnitude, to $10^{-8}$.
• With some enhancements, our experiment may be sensitive to Lorentz violation at the level of $9\times 10^{-20}$.