Improved Limit on a Temporal Variation of mp/me from Comparisons of Yb+ and Cs Atomic Clocks

Author(s): N. Huntemann, B. Lipphardt, Chr. Tamm, V. Gerginov, S. Weyers, and E. Peik

Single-ion clocks yield new limits on how much the proton-to-electron mass ratio and the fine structure constant change over time.

[Phys. Rev. Lett. 113, 210802] Published Mon Nov 17, 2014