Parafermions in a Kagome lattice of qubits for topological quantum computation

TL;DR

This paper demonstrates how to realize $ ext{Z}_4$ parafermions and Abelian anyons on a qubit lattice, enabling topological quantum computation with fault-tolerance and high noise thresholds.

Contribution

It introduces a method to engineer non-Abelian $ ext{Z}_4$ parafermions in a qubit lattice, surpassing the limitations of Majorana-based systems.

Findings

Realization of $ ext{Z}_4$ parafermions on a qubit lattice.

Generation of the entire $d=4$ Clifford group through braiding.

High noise thresholds achieved due to defect line engineering.

Abstract

Engineering complex non-Abelian anyon models with simple physical systems is crucial for topological quantum computation. Unfortunately, the simplest systems are typically restricted to Majorana zero modes (Ising anyons). Here we go beyond this barrier, showing that the $\mathbb{Z}_4$ parafermion model of non-Abelian anyons can be realized on a qubit lattice. Our system additionally contains the Abelian $D(\mathbb{Z}_4)$ anyons as low-energetic excitations. We show that braiding of these parafermions with each other and with the $D(\mathbb{Z}_4)$ anyons allows the entire $d=4$ Clifford group to be generated. The error correction problem for our model is also studied in detail, guaranteeing fault-tolerance of the topological operations. Crucially, since the non-Abelian anyons are engineered through defect lines rather than as excitations, non-Abelian error correction is not required. Instead the error correction problem is performed on the underlying Abelian model, allowing high noise thresholds to be realized.