Study of systematic effects at the 10⁻¹⁸ level on strontium optical lattice clocks and metrological applications

SYRTE is developing optical lattice clocks with strontium atoms. These clocks enable to lock the frequency of an ultra-stable laser probing an ensemble of 10e4 ultra-cold atoms tightly confined in an optical lattice. Improved performances of optical clocks bring variate applications in metrology of time and frequency, chronometric geodesy, or in fundamental physics. Two strontium optical lattice clocks are now operational at SYRTE and have shown fractionnal instability and incaccuracy of 2×10^–17. These cloks are already available for long and regular metrological campaign, in which their performances were confirmed through international comparisons. The continuation of their developpement at SYRTE is expected to reduce further the incaccuracy and instability of strontium clocks. This PhD thesis shows the state of developpement of the clock at SYRTE, and their recent improvement. A refined incaccuracy budget is presented, with studies that will contribute to reduce it to the 10^–18. A study of the light shift induced by the lattice laser on the clock transition is presented, with the description of a protocole that enables cancelation of of its atomic temperature dependancy, by the spectroscopie of clock carrier. The team also present the assembling of a new ultra high vacuum chamber, which is bound to reduce the inhomogeneities of the thermal radiation on the interrogated atoms, main contribution to the inaccuracy. Multiples results of comparisons with strontium clocks are describes, within both local and international comparisons with fiber links and satellites, and against microwaves and optical clcoks. This includes the first real time steering of the Temps Atomique Internationale (TAI).

optical lattice clocks, systematic measurements, comparisons, ultra high vacuum chamber, effusive oven