Precision Measurement of the Hydrogen1S−2SFrequency via a 920-km Fiber Link

Authors: Arthur Matveev, Christian G. Parthey, Katharina Predehl, Jānis Alnis, Axel Beyer, Ronald Holzwarth, Thomas Udem, Tobias Wilken, N. Kolachevsky, Michel Abgrall, Daniele Rovera, Christophe Salomon, Philippe Laurent, Gesine Grosche, Osama Terra, Thomas Legero, H. Schnatz, S. Weyers, Brett Altschul, Theodor W. Hänsch - Physical Review Letters 2013 cited by 218

We have measured the frequency of the extremely narrow $1S\mathrm{\text{\ensuremath{-}}}2S$ two-photon transition in atomic hydrogen using a remote cesium fountain clock with the help of a 920 km stabilized optical fiber. With an improved detection method we obtain ${f}_{1S\mathrm{\text{\ensuremath{-}}}2S}=2466\text{ }061\text{ }413\text{ }187\text{ }018\text{ }(11)\text{ }\text{ }\mathrm{Hz}$ with a relative uncertainty of $4.5\ifmmode\times\else\texttimes\fi{}{10}^{\ensuremath{-}15}$, confirming our previous measurement obtained with a local cesium clock [C. G. Parthey et al., Phys. Rev. Lett. 107, 203001 (2011)]. Combining these results with older measurements, we constrain the linear combinations of Lorentz boost symmetry violation parameters ${c}_{(TX)}=(3.1\ifmmode\pm\else\textpm\fi{}1.9)\ifmmode\times\else\texttimes\fi{}{10}^{\ensuremath{-}11}$ and $0.92{c}_{(TY)}+0.40{c}_{(TZ)}=(2.6\ifmmode\pm\else\textpm\fi{}5.3)\ifmmode\times\else\texttimes\fi{}{10}^{\ensuremath{-}11}$ in the standard model extension framework [D. Colladay, V. A. Kosteleck\'y, Phys. Rev. D. 58, 116002 (1998)].