Ultracold atomic gases with strong interactions

Speaker:Nobel Laureate Prof. Wolfgang Ketterle
Location:Lidow Rosen Auditorium (323)
Abstract:What form of matter can be simpler than a dilute gas of particles? The cases of non-interacting and weakly interacting particles are well understood.
So what happens if the interactions get stronger? Depending on the interactions this will lead to a vast variety of materials with strong correlations.
Simple models assume short range (delta function like) attractive or repulsive interactions. Such systems can be realized with ultracold atoms, using
the tools of atomic physics. We have studied a gas of ultracold fermions with both attractive and repulsive interactions. Fermions with attractive
interactions undergo a phase transition to superfluidity. This is the simplest system which captures the essence of existing superconductors, but also
extends to regimes where the transition temperature is very high. For repulsive interactions, a transition to a ferromagnetic phase has been predicted, but
our experiments have shown that such a transition does not take place. This illustrates the role of ultracold atoms as quantum simulators of seemingly
simple Hamiltonians, for which no reliable solutions have been found computationally.