CHERFAN Charbel: Quantum Chaos with a Potassium Condensate: effects of interactions and topology.

Thesis summary: The first objective of this thesis is to build an experiment that will produce degenerate quantum gases of ultracold atoms to study the transport properties in disordered quantum systems in the presence of interactions.

Our team has chosen to use potassium through the existence of a broad Feshbach resonance and relatively low magnetic field, which will properly control its diffusion length, and therefore the interactions. We have built an experimental system for cooling consisting of two vacuum chambers: a 'collection chamber' (10-8mbar) and the chamber of science (10-11mbar) in which the condensate will be created. For potassium, conventional sub-Doppler cooling (Sisyphe cooling) is inefficient because of the narrow hyperfine structure of the excited state of the D2 transition (767 nm). However, there is a sub-Doppler cooling version, called 'gray molasses', which can cool potassium more efficiently using the D1 transition (770 nm). A special feature of the laser system that we have developed is the generation of beams with fiber diodes at 1540 nm and 1534 nm, which are then amplified (thanks to telecom technology) and doubled in frequency, to generate wavelengths. necessary for cooling. These lasers are also frequency stabilized using a molecular transition of acetylene.

Once the condensate is created, it will be subjected to a sinusoidal optical potential pulsed in time, to experimentally realize the model of Quantum Pulsed Rotor (Quantum Kicked Rotor). In this system, classical particle transport can be inhibited by quantum interference effects, in close analogy with the Anderson model. This experiment will allow us to study N-body localization (Many-Body Localization) and topological effects in periodically modulated systems (Floquet Systems).

CHERFAN Charbel - charbel.cherfan.etu[chez]univ-lille[point]fr - 06 45 48 10 35

Thesis director: SZRIFTGISER Pascal
Co-supervisors: CHICIREANU Radu and CLEMENT Jean-François