Experimental Sample-Efficient and Device-Independent GHZ State Certification

TL;DR

This paper presents a practical, sample-efficient, and device-independent method for certifying a four-qubit GHZ state using few copies and non-IID data, advancing quantum resource verification.

Contribution

It introduces a novel protocol for device-independent quantum state certification applicable to few samples and non-IID data, demonstrated with a high-fidelity multipartite photon source.

Findings

Efficient certification of a four-qubit GHZ state in non-IID regime

Successful implementation with a high-fidelity photon source

Enables robust quantum information processing tasks

Abstract

The certification of quantum resources is a critical tool in the development of quantum information processing. In particular, quantum state verification is a fundamental building block for communication and computation applications, determining whether the involved parties can trust the resources at hand or whether the application should be aborted. Self-testing methods have been used to tackle such verification tasks in a device-independent (DI) setting. However, these approaches commonly consider the limit of large (asymptotic), identically and independently distributed (IID) samples, which weakens the DI claim and poses serious challenges to their experimental implementation. Here we overcome these challenges by adopting a theoretical protocol enabling the certification of quantum states in the few-copies and non-IID regime and by leveraging a high-fidelity multipartite entangled photon source. This allows us to show the efficient and device-independent certification of a single copy of a four-qubit GHZ state that can readily be used for the robust and reliable implementation of quantum information tasks.