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Continuous light shift correction in modualted coherent opoulation trapping clocks



V Shah, Vladislav Gerginov, P Schwindt, Svenja A. Knappe, Leo W. Hollberg, John E. Kitching


We demonstrate a simple technique to significantly improve the long term frequency stability of atomic clocks based on coherent population trapping (CPT). In this technique, the CPT feilds are created by a modulated diode laser and a slow servo is used to actively tune the laser modulation index to a value where the light shift vanishes. The observed clock frequency at this modulation index is given by the Rubidium hyperfine frequency when no light fields are present and this makes the clock frequency largely insensitive to variations in laser properties. In addition to reducing stringent requirements on the long term stability of laser temperature, laser frequency and RF modulation power, this technique may also significantly reduce freqeuency drifts related to laser aging. In the experiment, we demonstrate over one order of magnitude improvement in the stability of a clock that is limited by shift-induced frequency drifts.
Applied Physics Letters


coherent population trapping, frequency standards, light shifts


Shah, V. , Gerginov, V. , Schwindt, P. , Knappe, S. , Hollberg, L. and Kitching, J. (2006), Continuous light shift correction in modualted coherent opoulation trapping clocks, Applied Physics Letters, [online], (Accessed April 22, 2024)
Created October 13, 2006, Updated February 19, 2017