ABSTRACT:

The experiments performed with ultracold atomic gases trapped in optical speckle patterns or in bichromatic optical lattices provide us with a new versatile experimental setup to investigate the effects due to the interplay between interactions and random potentials in many-fermion systems. The details of the disorder, including the structure of the spatial correlations, can be experimentally characterized and accounted for in the theoretical models, paving the way to quantitative comparisons between theory and experiments.

In the first part of the talk, I will present results concerning the Stoner instability - i.e., the ferromagnetic transition induced by strong repulsive interactions - obtained via continuous-space quantum Monte Carlo (QMC) simulations . I will compare these QMC predictions for clean Fermi gases with very recent experiments performed at LENS. 

Then, I will discuss how the presence of an intense speckle pattern  - sufficiently strong to induce the Anderson localization of noninteracting particles - affects the Stoner instability.

Finally, I will discuss how QMC simulations combined with the theoretical tools familiar from the  modern theory of the insulating state allow us to predict how interactions affect the Anderson localization transition, considering a bichromatic optical lattice as the first testbed.

 

ll seminario si terrà mercoledì 8 Febbraio alle ore 17 in Aula E dell'edifico di Fisica.