An optical beam frequency reference with 10−14 range frequency instability

John Mcferran, John Hartnett, Andre Luiten

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    9 Citations (Scopus)


    The authors report on a thermal beam optical frequency reference with a fractional frequency instability of 9.2×10−14 at 1 s reducing to 2.0×10−14 at 64 s before slowly rising. The 1S0↔3P1 intercombination line in neutral 40Ca is used as a frequency discriminator. A diode laser at 423 nm probes the ground state population after a Ramsey–Bordé sequence of 657 nm light-field interactions on the atoms. The measured fractional frequency instability is an order of magnitude improvement on previously reported thermal beam optical clocks. The photon shot-noise of the read-out produces a limiting square root Λ-variance of 7×10−14/.
    Original languageEnglish
    Pages (from-to)Article number 031103, 3pp
    JournalApplied Physics Letters
    Issue number3
    Publication statusPublished - 2009


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