${}^{176}$Lu${}^{+}$ clock comparison at the $10^{-18}$ level via correlation spectroscopy

Abstract

We experimentally demonstrate agreement between two ${}^{176}$Lu${}^{+}$ frequency references using correlation spectroscopy. From a comparison at different magnetic fields, we obtain a quadratic Zeeman coefficient of $-4.89264(88)Hz/m{\mathrm{T}}^2$, which gives a corresponding fractional frequency uncertainty contribution of just $2.5\times 10^{-20}$ for comparisons at typical operating fields of 0.1\,mT. A subsequent comparison with both systems at 0.1\,mT, demonstrates a fractional frequency difference of $(-2.0\pm (3.7{)}_{\mathrm{stat}}\pm (0.9{)}_{\mathrm{sys}})\times 10^{-18}$, where `stat' and `sys' indicate statistical and systematic uncertainty, respectively.

Main text: 6 pages and 3 figures, Supplemental: 12 pages and 6 figs

Cited by in corpus (1)

• Evaluation of the relativistic redshift in frequency standards at KRISS