Detecting a Majorana-Fermion Zero Mode Using a Quantum Dot

TL;DR

This paper proposes an experimental setup using a quantum dot coupled to a p-wave superconducting nanowire to detect Majorana zero modes, with conductance measurements indicating topological phase transitions.

Contribution

It introduces a novel method to detect Majorana zero modes via conductance changes in a quantum dot system during topological phase transitions.

Findings

Conductance jumps by a factor of 1/2 at the topological transition

Zero temperature conductance peak is e^2/2h in the topological phase

Different conductance signatures distinguish trivial and fermionic zero modes

Abstract

We propose an experimental setup for detecting a Majorana zero mode consisting of a spinless quantum dot coupled to the end of a p-wave superconducting nanowire. The Majorana bound state at the end of the wire strongly influences the conductance through the quantum dot: Driving the wire through the topological phase transition causes a sharp jump in the conductance by a factor of 1/2. In the topological phase, the zero temperature peak value of the dot conductance (i.e. when the dot is on resonance and symmetrically coupled to the leads) is e^2/2h. In contrast, if the wire is in its trivial phase, the conductance peak value is e^2/h, or if a regular fermionic zero mode occurs on the end of the wire, the conductance is 0. The system can also be used to tune Flensberg's qubit system [PRL 106, 090503 (2011)] to the required degeneracy point.