Certifying the building blocks of quantum computers from Bell's theorem

TL;DR

This paper introduces a device-independent method based on Bell's theorem to certify the core components of quantum computers, including operations like storage and transfer, ensuring their suitability despite experimental imperfections.

Contribution

It provides the missing certification protocol for coherent quantum operations, completing the set of tools to verify all quantum computer building blocks.

Findings

Method is robust to experimental imperfections

Enables certification of quantum storage, processing, and transfer

Completes the set of certification tools for quantum computer components

Abstract

The power of quantum computers relies on the capability of their components to maintain faithfully and process accurately quantum information. Since this property eludes classical certification methods, fundamentally new protocols are required to guarantee that elementary components are suitable for quantum computation. These protocols must be device-independent, that is, they cannot rely on a particular physical description of the actual implementation if one is to qualify a block for all possible usages. Bell's theorem has been proposed to certify, in a device-independent way, blocks either producing or measuring quantum states. In this manuscript, we provide the missing piece: a method based on Bell's theorem to certify coherent operations such as storage, processing and transfer of quantum information. This completes the set of tools needed to certify all building blocks of a quantum computer. Our method is robust to experimental imperfections, and so can be readily used to certify that today's quantum devices are qualified for usage in future quantum computers.