Demonstration of the nearly continuous operation of an¹⁷¹Yb optical lattice clock for half a year

Abstract

Optical lattice clocks surpass primary Cs microwave clocks in frequency stability and accuracy, and are promising candidates for a redefinition of the second in the International System of Units (SI). However, the robustness of optical lattice clocks has not yet reached a level comparable to that of Cs fountain clocks which contribute to International Atomic Time (TAI) by the nearly continuous operation. In this paper, we report the long-term operation of an 171 Yb optical lattice clock with a coverage of 80.3% for half a year including uptimes of 93.9% for the first 24 days and 92.6% for the last 35 days. This enables a nearly dead-time-free frequency comparison of the optical lattice clock with TAI over months, which provides a link to the SI second with an uncertainty of low 10 −16. By using this link, the absolute frequency of the 1 S 0 − 3 P 0 clock transition of 171 Yb is measured as 518 295 836 590 863.54(26) Hz with a fractional uncertainty of 5.0×10 −16. This value is in agreement with the recommended frequency of 171 Yb as a secondary representation of the second.

Collective Spin-Light and Light-Mediated Spin-Spin Interactions in an Optical Cavity

“…One particular atom of interest is 171 Yb which is one of the leading atomic species used in optical lattice clocks [83,120,121]. Following Ref.…”

Free-bound excitation and predissociation of ytterbium dimers near theS01−P11atomic transition

“…Ytterbium is a lanthanide element with an electronic configuration similar to those of alkaline-earth atoms. Ultracold Yb atoms have been utilized for various applications such as quantum simulations [1,2] and atomic clocks [3][4][5][6]. One of the remarkable features of alkaline-earth(-like) atoms is the existence of metastable ( 3 P0, 3 P2) states of long radiative lifetimes on the order of seconds or more.…”

Nearly continuous Ca^+ optical clocks with stability at the 10^-18 level

“…Furthermore, to avoid the measurement errors induced by the use of flywheel clocks, reliable optical clocks that can continuously operate for long periods must be constructed [14,15]. In particular, for single-ion clocks, their stability must be improved for long-term quasi-continuous operation to allow for measurements or comparisons with a precision in the order of 10 -18 .…”

“…In particular, to ensure reproducibility of the definition of the second, several reference clocks are required internationally that can sustain long-term quasi-continuous operation [10][11][12][13][14]. Although different types of optical clocks with high accuracy in the order of 10 -18 have been realized in many laboratories worldwide [1][2][3][4][5], to our knowledge, there are only a few reports on long-term quasi-continuous performance of the optical clocks [14,15]. Considering this, extrapolation algorithms are required to account for the nonoperational time periods between working periods of the optical clocks in order to maintain a consistent international time scale [10][11][12][13]; alternatively, in these nonoperational time periods, the use of local oscillators (typically hydrogen masers) as flywheel clocks is necessary to maintain a consistent time scale.…”

“…To enable the use of these single-ion optical clocks with extremely low uncertainty for precise measurements or comparisons, currently, only two approaches exist, namely increasing their stability or averaging over longer effective times. Furthermore, to avoid the measurement errors induced by the use of flywheel clocks, reliable optical clocks that can continuously operate for long periods must be constructed [14,15]. In particular, for single-ion clocks, their stability must be improved for long-term quasi-continuous operation to allow for measurements or comparisons with a precision in the order of 10 -18 .…”