Direct comparison of a Ca+ single ion clock against a Sr optical lattice clock
arXiv:1208.4654 · doi:10.1364/OE.20.022034
Abstract
Optical frequency comparison of the 40Ca+ clock transition ν_{Ca} (2S1/2-2D5/2, 729nm) against the 87Sr optical lattice clock transition ν_{Sr}(1S0-3P0, 698nm) has resulted in a frequency ratio ν_{Ca} / ν_{Sr} = 0.957 631 202 358 049 9(2 3). The rapid nature of optical comparison allowed the statistical uncertainty of frequency ratio ν_{Ca} / ν_{Sr} to reach 1x10-15 in only 1000s and yielded a value consistent with that calculated from separate absolute frequency measurements of ν_{Ca} using the International Atomic Time (TAI) link. The total uncertainty of the frequency ratio using optical comparison (free from microwave link uncertainties) is smaller than that obtained using absolute frequency measurement, demonstrating the advantage of optical frequency evaluation. We report the absolute frequency of ^{40}Ca+ with a systematic uncertainty 14 times smaller than our previous measurement [1].
References in corpus (6)
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- Absolute frequency measurement of the 40Ca+ S1/2 - D5/2 clock transition
- The absolute frequency of the 87Sr optical clock transition
- Measuring the frequency of a Sr optical lattice clock using a 120-km coherent optical transfer
- An Optical Lattice Clock with Spin-polarized 87Sr Atoms
- Blackbody radiation shift in a 43Ca+ ion optical frequency standard