Certifying nonstabilizerness in quantum processors

TL;DR

This paper introduces set magic as a way to certify nonstabilizerness in quantum processors, enabling scalable detection of quantum resource without requiring entanglement.

Contribution

It connects recent coherence witnesses to set magic and demonstrates scalable certification of magic across multiple quantum processing units.

Findings

Set magic can be witnessed by two-state overlap inequalities.

Magic can be certified across multiple QPUs without entanglement.

The approach reduces resource demands for quantum certification.

Abstract

Nonstabilizerness, also known as magic, is a crucial resource for quantum computation. The growth in complexity of quantum processing units (QPUs) demands robust and scalable techniques for characterizing this resource. We introduce the notion of set magic: a set of states has this property if at least one state in the set is a non-stabilizer state. We show that certain two-state overlap inequalities, recently introduced as witnesses of basis-independent coherence, are also witnesses of multi-qubit set magic. We also show it is possible to certify the presence of magic across multiple QPUs without the need for entanglement between them and reducing the demands on each individual QPU.