LNE-SYRTE develops two optical lattice clocks with strontium atoms. They rely on the interrogation, with an "ultra-stable" of about 10⁴ ultra-cold atoms confined in a lattice generated by a powerful trapping laser. Because Sr lattice clocks combine an excellent frequency stability and a very good control of systematic effects, they are a promising candidate for a redefinition of the SI (Système international) second. Sr clocks at LNE-SYRTE now reach a frequency stabilit of 10^-15 at 1 second, and an accuracy of 4×10^-17.

High vacuum enclosure where strontium atoms are trapped in an optical lattice.

The research topics pursued with Sr lattice clocks at LNE-SYRTE include:

• Study of the ultimate performances for clocks, both in terms of frequency stability and accuracy
• Measurements of frequency ratios between different clocks for metrology and applications in fundamental physics (test of the standard model and relativity)
• Calibration of international time scales with optical clocks, for and operational redefinition of the SI second with an optical reference
• Study of quantum technologies to improve the frequency stability of optical clocks

Several breakthroughs in optical frequency metrology have been achieved at LNE-SYRTE

• First contribution of an optical clocks to TAI (Temps Atomique International) (2017).
• High precision measurement of frequency ratios with other species (Hg, Cs, Rb). The two former are amongst the best frequency ratio measurements independently reproduced in several laboratories.
• First "all optical" international clock comparison between two atomic clocks, via a coherent optical fibre link with PTB (2015)
• First comparison between two optical lattice clocks with an uncertainty better than the best realization of the SI second with micro-wave clocks. This comparison confirmed that the accuracy budget of optical lattice clocks have now outperformed the micro-wave standards (2013).
• Demonstration of optical lattice clocks able to autonomously operate for time intervals as long as three weeks (2016)
• High precision measurements of systematic effects dues to the confinement of the atoms, including polarization effects and hyperpolarizability

  

  Clock in operation: the blue lasers slow down the strontium atoms.

Publications

List of publications of the Sr project

Contact

Jérôme Lodewyck

• Email: jerome.lodewyck (at) obspm.fr
• Tel.: +33 (0) 1 40 51 22 24