Probing robust Majorana signatures by crossed Andreev reflection with a quantum dot

Abstract

We propose a three-terminal structure to probe robust signatures of Majorana zero modes. This structure consists of a quantum dot coupled to the normal-metal, s-wave superconducting, and Majorana Y-junction leads. The zero-bias differential conductance at zero temperature of the normal-metal lead peaks at 2e2/h, which will be deflected after Majorana braiding. This quantized conductance can entirely arise from the Majorana-induced crossed Andreev reflection, protected by the energy gap of the superconducting lead. We find that the effect of thermal broadening is significantly suppressed when the dot is on resonance. In the case in which the energy level of the quantum dot is much larger than the superconducting gap, tunneling processes are dominated by Majorana-induced crossed Andreev reflection. Particularly, a novel kind of crossed Andreev reflection equivalent to the splitting of charge quanta 3e occurs after Majorana braiding.

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