Theory of Coulomb blockaded transport in realistic Majorana nanowires

TL;DR

This paper develops a theoretical model for Coulomb blockade transport in Majorana nanowires, enabling analysis of subgap states and localization effects, and providing a tool for interpreting experimental data in topological superconducting systems.

Contribution

It introduces a generalized Meir-Wingreen formula for Coulomb blockade in Majorana nanowires, accounting for interactions and tunneling regimes, advancing understanding of transport phenomena in these systems.

Findings

Model reproduces key features of Coulomb blockade transport

Allows analysis of Andreev bound states and soft gaps

Provides a framework for interpreting experimental data

Abstract

Coulomb blockaded transport of topological superconducting nanowires provides an opportunity to probe the localization of states at both ends of the system in a two-terminal geometry. In addition, it provides a way for checking for subgap states away from the leads. At the same time, Coulomb blockade transport is difficult to analyze because of the interacting nature of the problem arising from the nonperturbative Coulomb interaction inherent in the phenomenon. Here we show that the Coulomb blockade transport can be modeled at the same level of complexity as quantum point contact tunneling that has routinely been used in mesoscopic physics to understand nanowire experiments provided we consider the regime where the tunneling rate is below the equilibration rate of the nanowire. This assumption leads us to a generalized Meir-Wingreen formula for the tunnel conductance which we use to study various features of the nanowire such as Andreev bound states, self-energy, and soft gap. We anticipate that our theory will provide a route to interpret Coulomb blockade transport in hybrid Majorana systems as resulting from features of the nanowire, such as Andreev bound states and soft gaps.