Unraveling a concealed resonance by multiple Kondo transitions in a quantum dot

Abstract

Kondo correlations are responsible for the emergence of a zero-bias peak in the low temperature differential conductance of Coulomb blockaded quantum dots. In the presence of a global SU(2)⊗SU(2) symmetry, which can be realized in carbon nanotubes, they also inhibit inelastic transitions which preserve the Kramers pseudospins associated to the symmetry. We report on magnetotransport experiments on a Kondo correlated carbon nanotube where resonant features at the bias corresponding to the pseudospin-preserving transitions are observed. We attribute this effect to a simultaneous enhancement of pseudospin-non-preserving transitions occurring at that bias. This process is boosted by asymmetric tunneling couplings of the two Kramers doublets to the leads and by asymmetries in the potential drops at the leads. Hence, the present work discloses a fundamental microscopic mechanisms ruling transport in Kondo systems far from equilibrium. arXiv:1908.11129v1 [cond-mat.str-el]

Feynman-Vernon influence functional approach to quantum transport in interacting nanojunctions: An analytical hierarchical study

“…The advantage of these approaches is to enable analytical solutions being intrinsically nonperturbative in both the tunneling and interaction. For example, generating functional methods have been used to treat zero-bias anomalies in metallic islands [66], and the nonequilibrium Kondo effect in the SIAM [67,68] and in carbon nanotube-based quantum dots [69][70][71]. However, a treatment of interacting nanojunctions based on an exact path-integral expression for the junction's RDM has not been discussed yet.…”

Feynman-Vernon influence functional approach to quantum transport in interacting nanojunctions: An analytical hierarchical study

“…The advantage of these approaches is to enable analytical solutions being intrinsically nonperturbative in both the tunneling and interaction. For example, generating functional methods have been used to treat zero-bias anomalies in metallic islands [64], and the nonequilibrium Kondo effect in the SIAM [65,66] and in carbon nanotube-based quantum dot [67][68][69]. However, a treatment of interacting nanojunctions based on an exact path integral expression for the junction's RDM has not been discussed yet.…”