Juliette BREUREC : "High performance Compact Cs cell Atomic Clock"

Abstract : This PhD thesis work aims to explore further the CPT (Coherent Population Trapping) approach for the demonstration of high-performance microwave cesium vapor cell clocks.
We begin with a thorough metrological characterization of a first clock. This clock uses an optimized pumping scheme named push-pull optical pumping (PPOP) and an pulsed interrogation technic (Ramsey-CPT or SABR-CPT : Symmetric Auto-Balanced Ramsey). A frequency stability at 1 s of 1×10^(-13) in Ramsey-CPT mode and 2×10^(-13) in SABR-CPT mode was demonstrated. We then measured dependencies of the clock frequency to numerous experimental parameters and demonstrated that the SABR-CPT sequence induces a drastic reduction of numerous dependency coefficients. A stability budget of 3.5×10^(-14) at 1 day was established. The temperature of passive optical components, the laser frequency, the microwave power and the magnetic field are main contributions to date. A degradation of the clock’s performances for τ≥100 s was also observed. Numerous investigations were conducted to understand its source.
The second research axis consisted in the design and development of a clock, with a comparable architecture but more compact (optical bench < 10 L). Following its design and its assembly, first characterizations of this clock were reported, such as the spectroscopy of the CPT resonance in both the continuous and the Ramsey-CPT regime. Some frequency shifts measurements are also reported. This clock also demonstrated a preliminary fractional frequency stability of 1.5×10^(-11) at 1 s, and 2.5×10^(-12) at 10^5 s in Ramsey-CPT.

Jury Composition  :

Rodolphe BOUDOT Directeur de recherche Université Marie et Louis Pasteur Directeur de thèse
Oriane LELIEVRE Ingénieure Thales AVS-MIS Examinateur
Caroline CHAMPENOIS Directrice de recherche Université d'Aix-Marseille Examinateur
Vincent GIORDANO Directeur de recherche Université Marie et Louis Pasteur Examinateur
Gaëtano MILETI Professeur Université de Neuchâtel Examinateur
Olivier LLOPIS Directeur de recherche LAAS-CNRS Rapporteur
Thomas ZANON-WILLETTE Maître de conférences Sorbonne Université Rapporteur

Localisation : SupMicrotech École Nationale Supérieure de Mécanique et des Microtechniques 26, rue de l’Épitaphe 25000 BESANÇON - salle Amphithéâtre Jules Haag