Confinement-induced zero-bias peaks in conventional superconductor hybrids

TL;DR

This paper demonstrates that confinement effects in superconductor hybrids can produce zero-bias conductance peaks similar to Majorana states, challenging the interpretation of such peaks as definitive signatures of topological Majorana modes.

Contribution

It reveals that trivial quasi zero-energy states can naturally form due to confinement, mimicking Majorana signatures without requiring topological conditions.

Findings

Confinement induces quasi zero-energy states in superconductor hybrids.

Zero-bias peaks can arise from trivial states, not necessarily Majoranas.

Confinement effects explain the ubiquity of zero-bias peaks in experiments.

Abstract

Majorana bound states in topological superconductors have been predicted to appear in the form of zero-bias conductance peaks of height $2e^{2}/h$, which represents one of the most studied signatures so far. Here, we show that quasi zero-energy states, similar to Majorana bound states, can naturally form in any superconducting hybrid junction due to confinement effects, without relation to topology. Remarkably, these topologically trivial quasi zero-energy states produce zero-bias conductance peaks, thus mimicking the most representative Majorana signature. Our results put forward confinement as an alternative mechanism to explain the ubiquitous presence of trivial zero-bias peaks and quasi zero-energy states in superconductor hybrids.