Sr lattice clock at 1 x 10(-16) fractional uncertainty by remote optical evaluation with a Ca clock.
Optical atomic clocks promise timekeeping at the highest precision and accuracy, owing to their high operating frequencies. Rigorous evaluations of these clocks require direct comparisons between them. We have realized a high-performance remote comparison of optical clocks over kilometer-scale urban distances, a key step for development, dissemination, and application of these optical standards. Through this remote comparison and a proper design of lattice-confined neutral atoms for clock operation, we evaluate the uncertainty of a strontium (Sr) optical lattice clock at the 1 x 10(-16) fractional level, surpassing the current best evaluations of cesium (Cs) primary standards. We also report on the observation of density-dependent effects in the spin-polarized fermionic sample and discuss the current limiting effect of blackbody radiation-induced frequency shifts.
Ludlow
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JILA, National Institute of Standards and Technology, and University of Colorado, Department of Physics, University of Colorado, Boulder, CO 80309-0440, USA.
Zelevinsky
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Campbell
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Blatt
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Boyd
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de Miranda
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Martin
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Thomsen
J W
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Foreman
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Ye
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Fortier
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Stalnaker
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Diddams
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Le Coq
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Barber
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Poli
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Lemke
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Beck
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Oates
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