Crystalline-Symmetry-Protected Majorana Modes in Coupled Quantum Dots

TL;DR

This paper introduces a minimal quantum dot array architecture to realize crystalline-symmetry-protected Majorana modes, enabling exploration of higher-order topological phases with potential experimental applications.

Contribution

It proposes a novel, simplified setup for creating and studying crystalline-symmetry-protected Majorana modes and higher-order topological phases in quantum dot systems.

Findings

Introduction of $ $-phase domain walls yields mirror-protected Majorana zero modes.

Closed loops of $ $-junctions simulate 2D higher-order topological phases.

$n$-vertices with dihedral symmetry host $n$ Majorana modes.

Abstract

We propose a minimalist architecture for achieving various crystalline-symmetry-protected Majorana modes in an array of coupled quantum dots. Our framework is motivated by the recent experimental demonstrations of two-site and three-site artificial Kitaev chains in a similar setup. We find that introducing a $\pi$-phase domain wall in the Kitaev chain leads to a pair of mirror-protected Majorana zero modes located at or near the junction. Joining two $\pi$-junctions into a closed loop, we can simulate two distinct classes of two-dimensional higher-order topological superconducting phases, both carrying symmetry-protected Majorana modes around the sample corners. As an extension of the $\pi$-junction, we further consider a general vertex structure where $n$ Kitaev chains meet, i.e., a Kitaev $n$-vertex. We prove that such an $n$-vertex, if respecting a dihedral symmetry group $D_n$, necessarily carries $n$ vertex-bound Majorana modes protected by the $D_n$ symmetry. Resilience of the junction and vertex Majorana bound states against disorder and correlation effects is also discussed. Our architecture paves the way for designing, constructing, and exploring a wide variety of artificial topological crystalline phases in experiments.