Chou, Yang-ZhiLevchenko, AlexFoster, Matthew S.2016-06-102016-06-102015Chou, Yang-Zhi, Levchenko, Alex and Foster, Matthew S.. "Helical Quantum Edge Gears in 2D Topological Insulators." <i>Physical Review Letters,</i> 115, no. 18 (2015) American Physical Society: 186404. http://dx.doi.org/10.1103/PhysRevLett.115.186404.https://hdl.handle.net/1911/90486We 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 (e2/h)(2K+1)/(K+1). At higher T, we predict a conductivity ∼T−4K+3. The conductivity for a single edge is also computed.engArticle is made available in accordance with the publisher's policy and may be subject to US copyright law. Please refer to the publisher's site for terms of use.Journal articlehttp://dx.doi.org/10.1103/PhysRevLett.115.186404