Topology from Triviality

TL;DR

This paper demonstrates that proximity effects between two initially trivial topological systems can induce new topological phases, revealing richer phase diagrams with unconventional topological states.

Contribution

It introduces a novel mechanism where trivial systems can become topologically non-trivial through proximity, expanding understanding of topological phase emergence.

Findings

Trivial systems can host topological phases when brought into proximity.

The phase diagram includes phases with mismatched topological states between substrate and wire.

Analytical and numerical methods confirm the existence of these unconventional phases.

Abstract

We show that bringing into proximity two topologically trivial systems can give rise to a topological phase. More specifically, we study a 1D metallic nanowire proximitized by a 2D superconducting substrate with a mixed s-wave and p-wave pairing, and we demonstrate both analytically and numerically that the phase diagram of such a setup can be richer than reported before. Thus, apart from the two "expected" well-known phases (i.e., where the substrate and the wire are both simultaneously trivial or topological), we show that there exist two peculiar phases in which the nanowire can be in a topological regime while the substrate is trivial, and vice versa.