Majorana fermion chain at the Quantum Spin Hall edge

TL;DR

This paper explores a one-dimensional Majorana fermion chain at a quantum spin Hall edge, analyzing its critical behavior and tunneling properties, with potential implications for topological quantum computing.

Contribution

It demonstrates a realization of a Majorana chain at a quantum spin Hall edge and maps it to the transverse field Ising model, revealing critical points and tunneling signatures.

Findings

Identification of a Majorana chain at QSH edges.

Mapping to the transverse field Ising model.

Voltage dependence of tunneling current as a probe.

Abstract

We study a realization of a 1d chain of Majorana bound states at the interfaces between alternating ferromagnetic and superconducting regions at a quantum spin Hall insulator edge. In the limit of well separated Majoranas, the system can be mapped to the transverse field Ising model. The disordered critical point can be reached by tuning the relative magnitude or phases of the ferromagnetic and superconducting order parameters. We compute the voltage dependence of the tunneling current from a metallic tip into the Majorana chain as a direct probe of the random critical state.