Seminar QuantAlps: Friday, 10th January 2025 at 9:30 am
Jean Dalibard (Collège de France)
Title: Superfluidity and quantum coherence: the two sides of the same coin, really?
Amphitheater Bergès, GreenEr
Abstract: Macroscopic quantum coherence emerges in fluids such as Bose-Einstein condensates, where a significant fraction of the particles share the same wave function. Superfluidity describes the rigidity of a gas or a liquid when we try to set it in motion. Although the two phenomena are often linked, they are not equivalent. In this lecture, I will use recent experiments with quantum gases to show that we can have a superfluid system with no long-range coherence, and conversely a fully coherent system with only a small superfluid fraction.