A localized impurity in a mesoscopic system of SU(N) fermions

In this talk, I will present our recent investigations of matter-wave flow of SU(N) fermions through a localized impurity in a mesoscopic ring pierced by an effective magnetic field.

In SU(N) fermionic rings, the flow of particles can be controlled by the effective magnetic field, with a strong dependence on the interactions, which give rise to fractional values of the angular momentum. The underlying origin of this phenomenon is due to the formation of composite bound states (attraction) and spinon excitations (repulsion).

I will explain how an impurity affects the persistent current in a complementary regime to the seminal work of Kane and Fisher, where we now focus on the mesoscopic regime. In bosonic systems, the barrier renormalizes the amplitude of the persistent current in a non-monotonous behavior, whereas for multi-component fermions, this has not been explored until now. Moreover, we observe that the smoothing out of the current, corresponding to a gap opening in the spectrum, only happens for particular states. We analyze the system through a combination of numerical and analytical approaches, including Exact diagonalization, DMRG and Bethe ansatz, which allows us to understand the underlying reasons for the observed behavior.