Tunneling spectra simulation of interacting Majorana wires

TL;DR

This paper uses DMRG to analyze how interactions influence tunneling spectra and Majorana zero-bias peaks in superconducting wires, providing insights into experimental observations of Majorana modes.

Contribution

Develops a DMRG-based method to simulate tunneling spectra of interacting Majorana wires, linking microscopic interactions to observable spectral features.

Findings

Interactions modify the Majorana zero-bias peak.

Bulk gap closure affects tunneling peaks during phase transitions.

Proximity peaks and Majorana peaks are influenced by topological changes.

Abstract

Recent tunneling experiments on InSb hybrid superconductor-semiconductor devices have provided hope for a stabilization of Majorana edge modes in a spin-orbit quantum wire subject to a magnetic field and superconducting proximity effect. Connecting the experimental scenario with a microscopic description poses challenges of different kind, such as accounting for the effect of interactions on the tunneling properties of the wire. We develop a density matrix renormalization group (DMRG) analysis of the tunneling spectra of interacting Majorana chains, which we explicate for the Kitaev chain model. Our DMRG approach allows us to calculate the spectral function down to zero frequency, where we analyze how the Majorana zero-bias peak is affected by interactions. From the study of topological phase transitions between the topological and trivial superconducting phase in the wire, we argue that the bulk gap closure generically affects both the proximity peaks and the Majorana peak, which should be observable in the transport signal.