title: Cooper-pair injection into quantum spin Hall insulators.
abstract: We theoretically study tunneling of Cooper pairs from a superconductor spanning a two-dimensional topological insulator strip into its helical edge states. The coherent low-energy electron-pair tunneling sets off positive current cross correlations along the edges, which reflect an interplay of two quantum-entanglement processes. Most importantly, superconducting spin pairing dictates a Cooper pair partitioning into the helical edge liquids, which transport electrons in opposite directions for opposite spin orientations. At the same time, Luttinger-liquid correlations fractionalize electrons injected at a given edge into counterpropagating charge pulses carrying definite fractions of the elementary electron charge.
authors.affiliation: Department of Physics and Astronomy, University of California, Los Angeles, California 90095, USA.
authors.forename: Koji
authors.initials: K
authors.lastname: Sato
authors.forename: Daniel
authors.initials: D
authors.lastname: Loss
authors.forename: Yaroslav
authors.initials: Y
authors.lastname: Tserkovnyak