Unveiling nontrivial fusion rule of Majorana zero mode using a fermionic mode

TL;DR

This paper proposes a method to demonstrate the nontrivial fusion rule of Majorana zero modes by attaching a fermionic mode and manipulating its energy and coupling, enabling charge pumping that distinguishes Majoranas from trivial states.

Contribution

It introduces a simple scheme using a fermionic mode attached to a Majorana zero mode to reveal nontrivial fusion rules through charge pumping in a nanowire system.

Findings

Charge pumping can realize zero or integer charge transfer depending on fusion loops.

Fusion loops are determined by zero-energy crossings in parameter space.

The method robustly distinguishes Majorana modes from trivial Andreev bound states.

Abstract

Fusing Majorana zero modes leads to multiple outcomes, a property being unique to non-Abelian anyons. Successful demonstration of this nontrivial fusion rule would be a hallmark for the development of topological quantum computation.Here we show that this can be done by simply attaching a fermionic mode to a single Majorana zero mode. Through modulation of the energy level of this fermionic mode as well as its coupling with the Majorana mode in different sequences, we show that a zero or integer charge pumping can be realized when different fusion loops are chosen. Such fusion loops are intimately related with the nontrivial fusion rule of Majorana modes and are solely determined by the crossings at zero energy in the parameter space. Finally we demonstrate our proposal in a nanowire-based topological superconductor coupled to a quantum dot. We show that the charge pumping is robust for MZMs in the real system irrespective of the initial condition of FM state, contrary to the case for trivial Andreev bound states. This provides a feasible way to distinguish Majorana modes from trivial Andreev bound states.