Majorana fermion realization and relevant transport processes in a triple-quantum dot system**Project supported by the New Century Excellent Talents in University of China (Grant No. NCET-10-0090), the National Natural Science Foundation of China (Grant Nos. 11474106, 11174088, and 11274124), the Program for Changjiang Scholars and Innovative Research Team in University of China (Grant No. IRT1243), and the Natural Science Foundation

Abstract

Nonequilibrium electronic transports through a system hosting three quantum dots hybridized with superconductors are investigated. By tuning the relative positions of the dot levels, we illustrate the existence of Majorana fermions and show that the Majorana feimions will either survive separately on single dots or distribute themselves among different dots with tunable probabilities. As a result, different physical mechanisms appear, including local Andreev reflection (LAR), cross Andreev reflection (CAR), and cross resonant tunneling (CRT). The resulting characteristics may be used to reveal the unique properties of Majorana fermions. In addition, we discuss the spin-polarized transports and find a pure spin current and a spin filter effect due to the joint effect of CRT and CAR, which is important for designing spintronic devices.