title: Helical Quantum Edge Gears in 2D Topological Insulators.
abstract: We show that two-terminal transport can measure the Luttinger liquid (LL) parameter K, in helical LLs at the edges of two-dimensional topological insulators (TIs) with Rashba spin-orbit coupling. We consider a Coulomb drag geometry with two coplanar TIs and short-ranged spin-flip interedge scattering. Current injected into one edge loop induces circulation in the second, which floats without leads. In the low-temperature (T→0) perfect drag regime, the conductance is (e^{2}/h)(2K+1)/(K+1). At higher T, we predict a conductivity ~T^{-4K+3}. The conductivity for a single edge is also computed.
authors.affiliation: Department of Physics and Astronomy, Rice University, Houston, Texas 77005, USA.
authors.forename: Yang-Zhi
authors.initials: YZ
authors.lastname: Chou
authors.affiliation: Department of Physics, University of Wisconsin-Madison, Madison, Wisconsin 53706, USA.
authors.forename: Alex
authors.initials: A
authors.lastname: Levchenko
authors.affiliation: Department of Physics and Astronomy, Rice University, Houston, Texas 77005, USA.|Rice Center for Quantum Materials, Rice University, Houston, Texas 77005, USA.
authors.forename: Matthew S
authors.initials: MS
authors.lastname: Foster