161 citations · 267 across the 4 of their papers we have counts for
3 papers
physics.atom-ph2015★ 30 cited
Observation of positronium annihilation in the 2S state: towards a new measurement of the 1S-2S transition frequency
D. A. Cooke, P. Crivelli, J. Alnis +8
We report the first observation of the annihilation of positronium from the 2S state. Positronium (Ps) is excited with a two-photon transition from the 1S to the 2S state where its…
physics.optics2009★ 161 cited
Optical frequency transfer via 146 km fiber link with 10^{-19} relative accuracy
G. Grosche, O. Terra, K. Predehl +5
We demonstrate the long-distance transmission of an ultra-stable optical frequency derived directly from a state-of-the-art optical frequency standard. Using an active stabilizatio…
physics.atom-ph2008★ 46 cited
New Measurement of the 2S Hyperfine Interval in Atomic Hydrogen
N. Kolachevsky, A. Matveev, J. Alnis +3
An optical measurement of the 2S hyperfine interval in atomic hydrogen using two-photon spectroscopy of the 1S-2S transition gives a value of 177 556 834.3(6.7) Hz. The uncertainty…