# Frequency comparison of two high-accuracy Al+ optical clocks.

@article{Chou2010FrequencyCO,
title={Frequency comparison of two high-accuracy Al+ optical clocks.},
author={Chin-wen Chou and David B. Hume and J C J Koelemeij and David J. Wineland and Till Rosenband},
journal={Physical review letters},
year={2010},
volume={104 7},
pages={
070802
}
}
We have constructed an optical clock with a fractional frequency inaccuracy of 8.6x10{-18}, based on quantum logic spectroscopy of an Al+ ion. A simultaneously trapped Mg+ ion serves to sympathetically laser cool the Al+ ion and detect its quantum state. The frequency of the {1}S{0}<-->{3}P{0} clock transition is compared to that of a previously constructed Al+ optical clock with a statistical measurement uncertainty of 7.0x10{-18}. The two clocks exhibit a relative stability of 2.8x10{-15}tau… Expand
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