Modular architectures for quantum networks

TL;DR

This paper proposes a modular, flexible quantum network architecture that efficiently generates multipartite entangled states, such as graph states, using shared resource states and minimal client participation, enabling secure and scalable quantum communication.

Contribution

It introduces a novel modular architecture for quantum networks utilizing multipartite entanglement, improving scalability, security, and resource efficiency over bipartite-based approaches.

Findings

Multipartite entanglement reduces memory and complexity requirements.

The architecture supports dynamic network extension and parallel requests.

Entanglement purification ensures high-fidelity and private entanglement among clients.

Abstract

We consider the problem of generating multipartite entangled states in a quantum network upon request. We follow a top-down approach, where the required entanglement is initially present in the network in form of network states shared between network devices, and then manipulated in such a way that the desired target state is generated. This minimizes generation times, and allows for network structures that are in principle independent of physical links. We present a modular and flexible architecture, where a multi-layer network consists of devices of varying complexity, including quantum network routers, switches and clients, that share certain resource states. We concentrate on the generation of graph states among clients, which are resources for numerous distributed quantum tasks. We assume minimal functionality for clients, i.e. they do not participate in the complex and distributed generation process of the target state. We present architectures based on shared multipartite entangled Greenberger-Horne-Zeilinger (GHZ) states of different size, and fully connected decorated graph states respectively. We compare the features of these architectures to an approach that is based on bipartite entanglement, and identify advantages of the multipartite approach in terms of memory requirements and complexity of state manipulation. The architectures can handle parallel requests, and are designed in such a way that the network state can be dynamically extended if new clients or devices join the network. For generation or dynamical extension of the network states, we propose a quantum network configuration protocol, where entanglement purification is used to establish high-fidelity states. The latter also allows one to show that the entanglement generated among clients is private, i.e. the network is secure.