Cluster-based architecture for fault-tolerant quantum computation

TL;DR

This paper introduces a cluster-based fault-tolerant quantum computing architecture that uses verified cluster states and postselection to achieve high noise thresholds and scalable quantum computation.

Contribution

It proposes a novel cluster-based architecture with recursive cluster construction and verification, differing from traditional circuit models, enabling scalable fault-tolerant quantum computing.

Findings

Achieves a high noise threshold of ~3% for quantum computation.

Uses verified cluster states to provide error-precorrection.

Reconciles postselection with scalability through localized verification.

Abstract

We present a detailed description of an architecture for fault-tolerant quantum computation, which is based on the cluster model of encoded qubits. In this cluster-based architecture, concatenated computation is implemented in a quite different way from the usual circuit-based architecture where physical gates are recursively replaced by logical gates with error-correction gadgets. Instead, some relevant cluster states, say fundamental clusters, are recursively constructed through verification and postselection in advance for the higher-level one-way computation, which namely provides error-precorrection of gate operations. A suitable code such as the Steane seven-qubit code is adopted for transversal operations. This concatenated construction of verified fundamental clusters has a simple transversal structure of logical errors, and achieves a high noise threshold ~ 3 % for computation by using appropriate verification procedures. Since the postselection is localized within each fundamental cluster with the help of deterministic bare controlled-Z gates without verification, divergence of resources is restrained, which reconciles postselection with scalability.