An introduction into fault-tolerant quantum computing

Abstract

We provide a basic introduction of the core ideas and theory surrounding fault-tolerant quantum computation. Quantum fault-tolerance essentially refers to avoiding the uncontrollable cascade of errors caused by the interaction of quantum-bits. The presented concepts underlay the theoretical framework of large-scale quantum computation and are the driving force for many recent experimental efforts to construct small to medium sized arrays of controllable quantum bits. We examine the basic principles of redundant quantum encoding, required to protect quantum bits from errors generated from both imprecise control and environmental interactions. The novelty of this work consists in the presentation of fault-tolerance principles from a classical distributed computing perspective, as this enables a more straightforward introduction without sacrificing generality. The practicality of fault-tolerant quantum computing is analysed after introducing a metric of scalability and discussing the factors influencing it.