Palestrante: Prof. Dr. Giacomo Roati, Univ. of Florence, Italy

Resumo: I will present two antithetic experimental studies, exploiting strongly interacting ultracold Fermi gases of 6Li atoms confined in optical potentials. In a first experiment, we create the analogous of a Josephson junction by bisecting BEC-BCS crossover superfluids by a thin optical barrier. We observe coherent dynamics in both the population and in the relative phase between the two superfluid reservoirs. For critical parameters, we see how the Josephson dynamics is affected by the presence of topological defects entering the superfluid bulk [1]. In a second experiment, we create an artificial ferromagnetic state by segregating degenerate spin mixtures into two initially disconnected reservoirs [2]. We study the spin dynamics for different interaction strengths and temperatures. For sufficiently high values of the inter-spin repulsive interactions and sufficiently low temperatures, we observe a softening of the spin dipole mode and a time-window during which spin diffusion is zeroed. Our measurements provide exciting new insights into the physics of attractive and repulsive Fermi gases.

[1] G. Valtolina et al., Science 350, 1505 (2015)

[2] G. Valtolina et al., arXiv:1605.07850v1 (2015)