Thursday, July 11, 2013

1307.2764 (James Jun He et al.)

BDI Class Topological Superconductors and Generating Entangled Spin
Currents in Quantum Anomalous Hall Insulators

James Jun He, Jiansheng Wu, T. P. Choy, Xiong-Jun Liu, Y. Tanaka, K. T. Law
The study of the properties and applications of topological phases has been one of the most important subjects in condensed matter physics in recent years. Here we show that inducing superconductivity on a AIII class topological insulator, which supports fermionic end states, results in a BDI class topological superconductor. The superconductor has two topological phases with one or two Majorana fermions (MFs) at each end of the wire. When two leads are attached to the two ends of the superconductor and in the phase with two MF end states, Cooper pairs from the superconductor can be efficiently split into the leads due to MF induced \emph{resonant} crossed Andreev reflections. More importantly, the currents leaving the two normal leads are entangled and spin-polarized. Therefore, the BDI class topological superconductor can be used as a novel source of entangled spin currents. These remarkable phenomena can be realized using quantum Anomalous Hall insulators in proximity to superconductors.
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