Superconducting analogue of the parafermion fractional quantum Hall states

TL;DR

This paper proposes a theoretical model for a superconducting analogue of parafermion fractional quantum Hall states, revealing potential platforms for realizing non-Abelian anyons and universal quantum computation.

Contribution

It introduces a new superconducting heterostructure that hosts $Z_k$ parafermion states, extending the understanding of topological phases and non-Abelian excitations in FQH systems.

Findings

Mapping FQH states to coupled 1D chains enables analysis of parafermion modes.

Inducing intra-chain pairing leads to gapless $Z_k$ parafermions for $k<4$.

The resulting topological superconductor hosts edge states described by $Z_k$ parafermion conformal field theory.

Abstract

Read and Rezayi $Z_k$ parafermion wavefunctions describe $\nu=2+\frac{k}{kM+2}$ fractional quantum Hall (FQH) states. These states support non-Abelian excitations from which protected quantum gates can be designed. However, there is no experimental evidence for these non-Abelian anyons to date. In this paper, we study the $\nu=2/k$ FQH-superconductor heterostructure and find the superconducting analogue of the $Z_k$ parafermion FQH state. Our main tool is the mapping of the FQH into coupled one-dimensional (1D) chains each with a pair of counter-propagating modes. We show that by inducing intra-chain pairing and charge preserving backscattering with identical couplings, the 1D chains flow into gapless $Z_{k}$ parafermions when $k< 4$. By studying the effect of inter-chain coupling, we show that every parafermion mode becomes massive except for the two outermost ones. Thus, we achieve a fractional topological superconductor whose chiral edge state is described by a $Z_k$ parafermion conformal field theory. For instance, we find that a $\nu=2/3$ FQH in proximity to a superconductor produces a $Z_3$ parafermion superconducting state. This state is topologically indistinguishable from the non-Abelian part of the $\nu=12/5$ Read-Rezay state. Both of these systems can host Fibonacci anyons capable of performing universal quantum computation through braiding operations.