Tuning the Drude weight of Dirac-Weyl fermions in one-dimensional ring traps

We study the response to an applied flux of an interacting system of Dirac-Weyl fermions confined in a one-dimensional (1D) ring. Combining analytical calculations with density-matrix renormalization group results, we show that tuning of the interactions leads to a unique many-body system that displays either a suppression or an enhancement of the Drude weight---the zero-frequency peak in the ac conductivity---with respect to the noninteracting value. An asymmetry in the interaction strength between same- and different-pseudospin Dirac-Weyl fermions leads to Drude weight enhancement. Vice versa, symmetric interactions lead to Drude weight suppression. Our predictions can be tested in mixtures of ultracold fermions in 1D ring traps.