Certifying the Topology of Quantum Networks: Theory and Experiment

TL;DR

This paper presents a scalable, efficient method for certifying the topology of quantum networks, enabling reliable characterization of entanglement distribution in complex quantum systems both theoretically and experimentally.

Contribution

It introduces a novel scheme for quantum network topology certification that works in semi-device independent scenarios and demonstrates its effectiveness through experimental implementation.

Findings

Successfully certified topology of six-qubit quantum networks

Applicable to semi-device independent scenarios

Enables simultaneous testing of multiple hypotheses

Abstract

Distributed quantum information in networks is paramount for global secure quantum communication. Moreover, it finds applications as a resource for relevant tasks, such as clock synchronization, magnetic field sensing, and blind quantum computation. For quantum network analysis and benchmarking of implementations, however, it is crucial to characterize the topology of networks in a way that reveals the nodes between which entanglement can be reliably distributed. Here, we demonstrate an efficient scheme for this topology certification. Our scheme allows for distinguishing, in a scalable manner, different networks consisting of bipartite and multipartite entanglement sources. It can be applied to semi-device independent scenarios also, where the measurement devices and network nodes are not well characterized and trusted. We experimentally demonstrate our approach by certifying the topology of different six-qubit networks generated with polarized photons, employing active feed-forward and time multiplexing. Our methods can be used for general simultaneous tests of multiple hypotheses with few measurements, being useful for other certification scenarios in quantum technologies.