Robust self-testing of multipartite GHZ-state measurements in quantum networks

TL;DR

This paper introduces a robust, device-independent method for self-testing multipartite GHZ-state measurements in quantum networks, enabling verification of quantum devices through local measurements and Bell inequality violations.

Contribution

It develops a general self-testing procedure for multipartite GHZ measurements, extending previous results and ensuring robustness against white noise.

Findings

Successfully self-tests N-qubit GHZ measurements using local measurements.

Recovers known results for three-qubit GHZ measurements as a special case.

Demonstrates robustness of the method against white noise.

Abstract

Self-testing is a device-independent examination of quantum devices based on correlations of observed statistics. Motivated by elegant progresses on self-testing strategies for measurements [Phys. Rev. Lett. 121, 250507 (2018)] and for states [New J. Phys. 20, 083041 (2018)], we develop a general self-testing procedure for multipartite generalized GHZ-state measurements. The key step is self-testing all measurement eigenstates for a general N-qubit multipartite GHZ-state measurement. Following our procedure, one only needs to perform local measurements on N-2 chosen parties of the N-partite eigenstate and maintain to achieve the maximal violation of tilted Clauser-Horne-Shimony-Holt (CHSH) Bell inequality for remaining two parties. Moreover, this approach is physically operational from an experimental point of view. It turns out that the existing result for three-qubit GHZ-state measurement is recovered as a special case. Meanwhile, we develop the self-testing method to be robust against certain white noise.