Probing Robust Majorana Signatures by Crossed Andreev Reflection with a Quantum Dot

TL;DR

This paper proposes a three-terminal device with a quantum dot to detect Majorana zero modes through conductance signatures, highlighting robustness against thermal effects and a novel 3e charge splitting after braiding.

Contribution

It introduces a new device setup that isolates Majorana signatures via crossed Andreev reflection, including the observation of a unique 3e charge splitting phenomenon.

Findings

Quantized zero-bias conductance peaks at 2e^2/h due to Majorana modes

Thermal broadening effects are suppressed on resonance

Observation of a 3e charge splitting after Majorana braiding

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 $2e^{2}/h$, 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 that 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.