Dynamics of repulsive Fermi gases

Abstract

Physics Pump-probe techniques, in which a short light pulse knocks the system out of equilibrium and another pulse is then used to monitor the dynamics, are commonplace in solid-state physics. Amico et al. used such a technique in a fermionic atomic gas to study what happens when the gas is plunged into a regime where the atoms strongly repel one another. The nature of this regime in an even mixture of two spin states has been debated—a ferromagnetic state was expected, but instead the atoms had a tendency to form pairs. Here, the researchers disentangled the two pathways and found that correlations consistent with ferromagnetism initially increased faster than the pairs formed, but neither clearly dominated over the other. Phys. Rev. Lett. 121 , 253602 (2018).