Calcium optical frequency standard with ultracold atoms: Approaching10−15relative uncertainty
| Autor: | Christian Lisdat, Paul-Eric Pottie, Fritz Riehle, Juergen Helmcke, H. Stoehr, Burghard Lipphardt, G. Wilpers, Harald Schnatz, C. Degenhardt, Uwe Sterr, T. Nazarova |
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| Rok vydání: | 2005 |
| Předmět: | |
| Zdroj: | Physical Review A. 72 |
| ISSN: | 1094-1622 1050-2947 |
| DOI: | 10.1103/physreva.72.062111 |
| Popis: | An optical frequency standard based on an ensemble of neutral calcium atoms laser-cooled to $12\phantom{\rule{0.3em}{0ex}}\ensuremath{\mu}\mathrm{K}$ has been realized. By using ultracold atoms, one major previous source of uncertainty, the residual Doppler effect, was reduced. We show that cold collisions contribute a negligible amount to the uncertainty. The influence of a temporal evolution of the phase of the laser pulses used to interrogate the clock transition was measured and corrected for. The frequency of the clock transition at $657\phantom{\rule{0.3em}{0ex}}\mathrm{nm}$ was referenced to the caesium fountain clock of PTB utilizing a femtosecond comb generator with a fractional uncertainty of $1.2\ifmmode\times\else\texttimes\fi{}{10}^{\ensuremath{-}14}$. The transition frequency was determined to be $(455\phantom{\rule{0.2em}{0ex}}986\phantom{\rule{0.2em}{0ex}}240\phantom{\rule{0.2em}{0ex}}494\phantom{\rule{0.2em}{0ex}}144\ifmmode\pm\else\textpm\fi{}5.3)\phantom{\rule{0.3em}{0ex}}\mathrm{Hz}$, making the calcium clock transition one of the most accurately known optical transitions. A frequency stability of $3\ifmmode\times\else\texttimes\fi{}{10}^{\ensuremath{-}15}$ at $100\phantom{\rule{0.3em}{0ex}}\mathrm{s}$ averaging time was achieved and the noise contributions that limit to the observed stability were analyzed in detail. Additionally, the natural linewidth of the clock transition has been determined. |
| Databáze: | OpenAIRE |
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