Thesis defense of Alfred HAMMOND

Thesis defense of Alfred HAMMOND, PhD student in the Quantum gases group of the LCF, on Wednesday 27 September 2023 at 2pm in the Auditorium of the Institut d'Optique Graduate School in Palaiseau, on the topic: "Collective effects in the ultra-cold gases of radio-frequency-dressed potassium-39".

Abstract: "Like Van der Waals gases, quantum gases have universal thermodynamic properties close to those of the perfect gas. A dilute quantum fluid of neutral particles has an equation of state with few intrinsic parameters. The use of a mixture of two Bose-Einstein condensates makes it possible to reduce or even completely cancel out certain terms in the fluid's dynamic equation. In this context, it has been experimentally observed that the physics of an atomic gas dressed by a radio-frequency field (quantum mixing) is much richer than in the absence of the field. On the one hand, collective effects that are usually negligible - three-body elastic interactions - appear and become predominant in the mean field properties of the fluid. On the other hand, effects beyond the mean field - renormalisation of interactions and zero-point quantum energy - are modified and exalted. As a result, we have been able to observe novel dynamical properties in radio-frequency-dressed quantum gases of potassium-39."