Revisit the non-locality of Majorana zero modes and teleportation: Bogoliubov-de Gennes equation based treatment

TL;DR

This paper revisits the nonlocality and teleportation properties of Majorana zero modes, clarifies theoretical inconsistencies, and predicts a conductance value of e^2/h, which may influence future experimental analyses.

Contribution

It introduces a unified single-particle-wavefunction approach to quantum transport for Majorana systems, reconciling different theoretical frameworks and revisiting tunneling spectroscopy predictions.

Findings

Predicts zero-bias conductance of e^2/h for symmetric lead coupling

Reconciles Bogoliubov-de Gennes treatment with second quantization methods

Suggests reexamination of existing Majorana tunneling experiments

Abstract

The nonlocal nature of the Majorana zero modes implies an inherent teleportation channel and unique transport signatures for Majorana identification. In this work we make an effort to eliminate some inconsistencies between the Bogoliubov-de Gennes equation based treatment and the method using the associated regular fermion number states of vacancy and occupation within the `second quantization' framework. We first consider a rather simple `quantum dot--Majorana wire--quantum dot' system, then a more experimentally relevant setup by replacing the quantum dots with transport leads. For the latter setup, based on the dynamical evolution of electron-hole excitations, we develop a single-particle-wavefunction approach to quantum transport, which renders both the conventional quantum scattering theory and the steady-state nonequilibrium Green's function formalism as its stationary limit. Further, we revisit the issue of Majorana tunneling spectroscopy and consider in particular the two-lead coupling setup. We present comprehensive discussions with detailed comparisons, and predict a zero-bias-limit conductance of $e^2/h$ (for symmetric coupling to the leads),which is a half of the popular result of the zero-bias-peak, or, the so-called Majorana quantized conductance ($2e^2/h$). The present work may arouse a need to reexamine some existing studies and the proposed treatment is expected to be involved in analyzing future experiments in this fast developing field.