Nonequilibrium dynamics of a two-channel Kondo system due to a quantum quench

Recent experiments by Potok have demonstrated a remarkable tunability between a single-channel Fermi-liquid fixed point and a two-channel non-Fermi-liquid fixed point. Motivated by this we study the nonequilibrium dynamics due to a sudden quench of the parameters of a Hamiltonian from a single-channel to a two-channel anisotropic Kondo system. We find a distinct difference between the long-time behavior of local quantities related to the impurity spin as compared to that of bulk quantities related to the total (conduction electrons plus impurity) spin of the system. In particular, the local impurity spin and the local spin susceptibility are found to equilibrate but in a very slow power-law fashion which is peculiar to the non-Fermi-liquid properties of the Hamiltonian. In contrast, we find a lack of equilibration in the two-particle expectation values related to the total spin of the system.