Quantum-logic-based <mml:math xmlns:mml="http://www.w3.org/1998/Math/MathML" display="inline" overflow="scroll"><mml:msup><mml:mi/><mml:mn>25</mml:mn></mml:msup></mml:math><mml:math xmlns:mml="http://www.w3.org/1998/Math/MathML" display="inline" overflow="scroll"><mml:mi>Mg</mml:mi></mml:math><mml:math xmlns:mml="http://www.w3.org/1998/Math/MathML" display="inline" overflow="scroll"><mml:msup><mml:mi/><mml:mo>+</mml:mo></mml:msup></mml:math>-<mml:math xmlns:mml="http://www.w3.org/1998/Math/MathML" display="inline" overflow="scroll"><mml:msup><mml:mi/><mml:mn>27</mml:mn></mml:msup></mml:math><mml:math xmlns:mml="http://www.w3.org/1998/Math/MathML" display="inline" overflow="scroll"><mml:mi>Al</mml:mi></mml:math><mml:math xmlns:mml="http://www.w3.org/1998/Math/MathML" display="inline" overflow="scroll"><mml:msup><mml:mi/><mml:mo>+</mml:mo></mml:msup></mml:math> optical frequency standard for the redefinition of the SI second
Zhiyu Ma, Ke Deng, Z. Y. Wang, Wenyu Wei, P. Hao, H. X. Zhang, Liren Pang, Biao Wang, Fang-Fei Wu, H. L. Liu, W. H. Yuan, Jiantao Chang, J. X. Zhang, Quanying Wu, Jie Zhang, Z. H. Lu
Abstract
Optical clocks have been demonstrated to be good choices to redefine the SI ``second.'' With this goal, we have constructed a quantum-logic-based ${}^{27}$$\mathrm{Al}$${}^{+}$ ion optical clock with a fractional frequency uncertainty of $1.6\ifmmode\times\else\texttimes\fi{}{10}^{\ensuremath{-}18}$. A ${}^{25}$$\mathrm{Mg}$${}^{+}$ ion is used as the logic ion for sympathetic cooling, state readout, and frequency-shift measurement of the ${}^{27}$$\mathrm{Al}$${}^{+}$ ion. The stability of the optical clock is $2.6\ifmmode\times\else\texttimes\fi{}{10}^{\ensuremath{-}15}/\sqrt{\ensuremath{\tau}}$, measured with a self-comparison method.