Quantized zero bias conductance plateau in semiconductor-superconductor heterostructures without non-Abelian Majorana zero modes

TL;DR

This paper demonstrates that quantized zero bias conductance plateaus can arise from partially separated Andreev bound states in semiconductor-superconductor heterostructures, without requiring non-Abelian Majorana zero modes, challenging previous interpretations.

Contribution

It shows that robust conductance plateaus can be produced by trivial ps-ABSs, indicating such features are not definitive evidence of Majorana zero modes.

Findings

Quantized conductance plateaus can originate from trivial ps-ABSs.

These plateaus are robust over various experimental parameters.

Observation of conductance plateaus alone does not confirm Majorana modes.

Abstract

We show that partially separated Andreev bound states (ps-ABSs), comprised of pairs of overlapping Majorana bound states (MBSs) emerging in quantum dot-semiconductor-superconductor heterostructures, produce robust zero bias conductance plateaus in end-of-wire charge tunneling experiments. These plateaus remain quantized at $2e^2/h$ over large ranges of experimental control parameters. In light of recent experiments reporting the observation of robust $2e^2/h$-quantized conductance plateaus in local charge tunneling experiments, we perform extensive numerical calculations to explicitly show that such quantized conductance plateaus, which are obtained by varying control parameters such as the tunnel barrier height, the super gate potential, and the applied magnetic field, can arise as a result of the existence of ps-ABSs. Because ps-ABSs can form rather generically in the topologically trivial regime, even in the absence of disorder, our results suggest that the observation of a robust quantized conductance plateau does not represent sufficient evidence to demonstrate the existence of non-Abelian topologically-protected Majorana zero modes localized at the opposite ends of a wire.