1303.2747 (M. A. Hohensee et al.)

Limits on violations of Lorentz symmetry and the Einstein equivalence
principle using radio-frequency spectroscopy of atomic dysprosium    [PDF]

M. A. Hohensee, N. Leefer, D. Budker, C. Harabati, V. A. Dzuba, V. V. Flambaum

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 gravitational redshift anomalies for electrons to the level of $10^{-8}$. With some enhancements, our experiment may be sensitive to Lorentz violation at the level of $9\times 10^{-20}$.

View original: http://arxiv.org/abs/1303.2747