title: 6π Josephson Effect in Majorana Box Devices.
abstract: We study Majorana devices featuring a competition between superconductivity and multichannel Kondo physics. Our proposal extends previous work on single-channel Kondo systems to a topologically nontrivial setting of a non-Fermi liquid type, where topological superconductor wires (with gap Δ) represent leads tunnel coupled to a Coulomb-blockaded Majorana box. On the box, a spin degree of freedom with Kondo temperature T_{K} is nonlocally defined in terms of Majorana states. For Δ≫T_{K}, the destruction of Kondo screening by superconductivity implies a 4π-periodic Josephson current-phase relation. Using a strong-coupling analysis in the opposite regime Δ≪T_{K}, we find a 6π-periodic Josephson relation for three leads, with critical current I_{c}≈eΔ^{2}/ℏT_{K}, corresponding to the transfer of fractionalized charges e^{*}=2e/3.
authors.affiliation: Institut für Theoretische Physik, Heinrich-Heine-Universität, D-40225 Düsseldorf, Germany.
authors.forename: A
authors.initials: A
authors.lastname: Zazunov
authors.affiliation: Institut für Theoretische Physik, Heinrich-Heine-Universität, D-40225 Düsseldorf, Germany.
authors.forename: F
authors.initials: F
authors.lastname: Buccheri
authors.affiliation: International Institute of Physics, Universidade Federal do Rio Grande do Norte, 59012-970 Natal, Brazil.|INFN, Sezione di Perugia, Via Alessandro Pascoli, I-06123 Perugia, Italy.
authors.forename: P
authors.initials: P
authors.lastname: Sodano
authors.affiliation: Institut für Theoretische Physik, Heinrich-Heine-Universität, D-40225 Düsseldorf, Germany.
authors.forename: R
authors.initials: R
authors.lastname: Egger