A clock network for geodesy and fundamental science

Abstract

Leveraging the unrivalled performance of optical clocks as key tools for geo-science, for astronomy and for fundamental physics beyond the standard model requires comparing the frequency of distant optical clocks faithfully. Here, we report on the comparison and agreement of two strontium optical clocks at an uncertainty of 5 × 10−17 via a newly established phase-coherent frequency link connecting Paris and Braunschweig using 1,415 km of telecom fibre. The remote comparison is limited only by the instability and uncertainty of the strontium lattice clocks themselves, with negligible contributions from the optical frequency transfer. A fractional precision of 3 × 10−17 is reached after only 1,000 s averaging time, which is already 10 times better and more than four orders of magnitude faster than any previous long-distance clock comparison. The capability of performing high resolution international clock comparisons paves the way for a redefinition of the unit of time and an all-optical dissemination of the SI-second.

Absolute frequency measurement of the ${{}^{1}}{{\text{S}}_{0}}$ – ${{}^{3}}{{\text{P}}_{0}}$ transition of171Yb

“…Table 1 shows the uncertainty budget for the 171 Yb optical lattice frequency standard. The fractional uncertainty for the measurement reported here is 1.5 10 16 × − . The contributions of the systematic effects will be discussed below.…”

“…In the low density regime ITCsF2 contributes to an uncertainty of 3.0 10 16 × − with a stability of 3.6 10 s…”

The Application of Coherent Local Time for Optical Time Transfer and the Quantification of Systematic Errors in Satellite Laser Ranging

“…For this purpose, optical time transfer via SLR will play an important role. In an environment, where major national standards laboratories currently develop highly accurate two-way frequency comparison techniques, in order to compare the frequency of optical clocks over distances of thousands of km (Lisdat et al 2016), laser time transfer by SLR techniques can be a valuable extension on the route to extend the coherence of time over larger distances on the ground and also into the near Earth orbit. Precise clocks in space like those of the ACES project are very suitable candidates for this purpose.…”

Inertial quantum sensors using light and matter

“…There are two main reasons for this. Atomic physics experiments can reach incredibly high accuracy (for example, clock synchronization at levels of a few 10 −17 [61] and 10 −18 [62] of relative accuracy), and have several control parameters which, for instance, allow one to isolate and measure individual relativistic terms by using their scalings with these parameters.…”