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PhD: Correlations of Intensity: Cold Atoms to Quantum Optics and Astrophysics

The measure of the light source coherence properties is an important point in their characterization. This measurement is generally carried out by interferometry, via the measurement of the correlations of the electric field. But it is also possible to go to higher order with the study of intensity correlations. First applicated in astrophysics via the measurement of spatial correlations of intensity, with the very famous Handbury Brown and Twiss experience, it has allowed to measure the diameter of many stars. Realized in the time domain, it is a particularly powerful method, among others in quantum optics to characterize the non-classical states of light. 
In our research group, we study the properties of ligt spread by a messy environment. This environment can vary from the most simple, like milk, to the most addvanced like a cell containing steam or a cold atom cloud. The very special properties of these (strong resonances, internal structure of the diffusers, mechanical effect of the light on the atoms, …) give rise to a particularly rich physics. The goal of this thesis is to focus on the study of the correlations of intensity of the light diffused by a cloud of cold atoms when this one is illuminated by several laser beams. This thesis will take place on one of the cold atom experiences of the group, but it could also be accompanied  by a modeling component, in collaboration with a Brazilian team, allowing either to understand and interpret experimental signals, or  guide futur researches on the experiment. The ultimate goal will be to detect signatures of non-classical phenomenoms, and therefore quantum, in the matter light interaction. All these experiments will be an important step towards the improvement of this astrophysical intensity correlation technique, which we are also implementing at the Calern Observatory.

References :
[1] Mollow triplet in cold atoms, L. Ortiz-Gutierrez et al., arXiv:1901.07816 (2019)
[2] Diffusing-Wave Spectroscopy of cold atoms in ballistic motion, A. Eloy et al., Phys. Rev.
A 97, 013810
(2018).
[3] HBT interferometry revival: temporal correlation on three bright stars, W. Guérin et
al., MNRAS 472, 4126 (2017).

More info and application here