Distinguishing topological Majorana bound states from trivial Andreev bound states: Proposed tests through differential tunneling conductance spectroscopy

TL;DR

This paper proposes experimental tests using tunneling spectroscopy to reliably distinguish between topological Majorana bound states and trivial Andreev bound states in nanowires, addressing false positives in zero-bias conductance peaks.

Contribution

It introduces specific, practical experimental protocols to differentiate Majorana from Andreev states without relying on complex nonlocal measurements.

Findings

Zero-bias peaks can arise from trivial states, mimicking Majorana signatures.

Proposed local perturbation schemes can distinguish between the two types of bound states.

Numerical simulations support the effectiveness of the proposed experimental tests.

Abstract

Trivial Andreev bound states arising from chemical potential variations could lead to zero-bias tunneling conductance peaks at finite magnetic fields in class $D$ nanowires, precisely mimicking the predicted zero-bias conductance peaks arising from the topological Majorana bound states. This finding raises a serious question on the efficacy of using zero-bias tunneling conductance peaks, by themselves, as evidence supporting the existence of topological Majorana bound states in nanowires. In the current work, we provide specific experimental protocols for tunneling spectroscopy measure- ments to distinguish between Andreev and Majorana bound states without invoking more demand- ing nonlocal measurements which have not yet been successfully performed in nanowire systems. In particular, we discuss three distinct experimental schemes involving response of the zero-bias peak to local perturbations of the tunnel barrier, overlap of bound states from the wire ends, and most compellingly, introducing a sharp localized potential in the wire itself to perturb the zero-bias tun- neling peaks. We provide extensive numerical simulations clarifying and supporting our theoretical predictions.