The Quantum Internet is commonly envisioned as a network that transports quantum states and distributes entanglement as the key resource underpinning distributed quantum applications. This view is necessary but incomplete if quantum phenomena are confined to what the network carries or manages, while network functionalities remain grounded predominantly in classical abstractions. This Perspective advances a broader thesis: quantum phenomena can also participate directly in the realization of network functionalities. We first establish the architectural baseline by introducing entanglement as a stateful network resource whose operational condition is non-locally distributed across remote nodes, evolves through manipulation or consumption, and degrades over time through decoherence. Its evolving state must therefore remain visible to the functionalities acting on it. We then move beyond resource visibility and use two mechanisms as proof points of a broader quantum-native functional design space: entanglement generation during propagation through coherent spatial-path superposition, and operational connectivity induced by shared entanglement that can depart from the physical graph. These examples show that paths, neighbors, or participating nodes may become operationally relevant in ways determined by quantum coherence and shared entanglement, rather than by physical connectivity alone. We identify Quantum Addressing as a transversal abstraction capable of representing such relations while complementing, rather than replacing, classical addressing and signaling. The resulting perspective broadens the Quantum Internet from transporting quantum information and distributing entanglement to exploiting quantum phenomena in network functioning, opening a coupled frontier spanning routing, forwarding, control, and functionality placement.
The Quantum Internet is commonly envisioned as a network that transports quantum states and distributes entanglement as the key resource underpinning distributed quantum applications. This view is necessary but incomplete if quantum phenomena are confined to what the network carries or manages, while network functionalities remain grounded predominantly in classical abstractions. This Perspective advances a broader thesis: quantum phenomena can also participate directly in the realization of network functionalities. We first establish the architectural baseline by introducing entanglement as a stateful network resource whose operational condition is non-locally distributed across remote nodes, evolves through manipulation or consumption, and degrades over time through decoherence. Its evolving state must therefore remain visible to the functionalities acting on it. We then move beyond resource visibility and use two mechanisms as proof points of a broader quantum-native functional design space: entanglement generation during propagation through coherent spatial-path superposition, and operational connectivity induced by shared entanglement that can depart from the physical graph. These examples show that paths, neighbors, or participating nodes may become operationally relevant in ways determined by quantum coherence and shared entanglement, rather than by physical connectivity alone. We identify Quantum Addressing as a transversal abstraction capable of representing such relations while complementing, rather than replacing, classical addressing and signaling. The resulting perspective broadens the Quantum Internet from transporting quantum information and distributing entanglement to exploiting quantum phenomena in network functioning, opening a coupled frontier spanning routing, forwarding, control, and functionality placement.
The key objective of the Quantum Internet is the distribution and manipulation of entanglement to enable unprecedented applications. This requires a radical departure from classical Internet design principles, such as the end-to-end argument, due to the inherently stateful and non-local nature of entanglement, which demands coordinated in-network operations and persistent state awareness. To this end, we propose a novel hierarchical Quantum Internet architecture centered on the concept ofEntanglement-Defined Controller(EDC). This architectural design constitutes the foundational layer, by enabling a clear separation between control and data planes. While necessary, this separation is insufficient to manage entanglement resources, requiring aquantum-native control plane. Consequently, we propose aquantum addressing schemethat embeds quantumness directly into node identifiers, allowing the network to natively track and manipulate entanglement as a dynamic resource. Built upon these two interdependent pillars – EDC-based architecture and quantum addressing – we design aquantum-native routing protocolthat achieves scalability through compact routing tables, by efficiently operating over entanglement-defined topologies. Finally, we design aquantum address splittingfunctionality based on Schrödinger’s oracles that generalizes classical match-and-forward logic to the quantum domain. Collectively, these contributions demonstrate, for the first time, the fundamental advantages of quantum-by-design network control for enabling scalable quantum networking.
The design of the Quantum Internet protocol stack is at its infancy and early-stage conceptualization. And different heterogeneous proposals are currently available in the literature. The underlying assumption of the existing proposals is that they implicitly mimic classical Internet Protocol design principles: “ A name indicates what we seek. An address indicates where it is. A route indicates how to get there ”. Hence the network nodes are labeled with classical addresses, constituted by classical bits, and these labels aim at reflecting the node location within the network topology. In this paper, we argue that this twofold assumption of classical and location-aware addressing constitutes a restricting design option, which prevents to scale the quantumness to the network functionalities, beyond simple information encoding/decoding. On the contrary, by embracing quantumness within the node addresses, quantum principles and phenomena could be exploited for enabling a quantum native functioning of the entire communication network. This will unleash the ultimate vision and capabilities of the Quantum Internet.
The Quantum Internet, a network interconnecting remote quantum devices through quantum links in synergy with classical ones, is envisioned as the final stage of the quantum revolution, opening fundamentally new communications and computing capabilities. But the Quantum Internet is governed by the laws of quantum mechanics. Phenomena with no counterpart in classical networks, such as no-cloning, quantum measurement, entanglement and quantum teleportation, impose new challenging constraints for network design. Specifically, classical network functionalities are based on the assumption that classical information can be safely read and copied. However, this assumption does not hold in the Quantum Internet. As a consequence, its design requires a major network-paradigm shift to harness the quantum mechanics specificities. The goal of this work is to shed light on the challenges and open problems of Quantum Internet design. We first introduce some basic knowledge of quantum mechanics, needed to understand the differences between a classical and a quantum network. Then, we introduce quantum teleportation as the key strategy for transmitting quantum information without physically transferring the particle that stores the quantum information or violating the principles of quantum mechanics. Finally, the key research challenges to design quantum communication networks are discussed.
The coming Quantum Internet will bring us new capabilities: advanced cryptographic functions, high-precision sensor networks for uses such as high-resolution astronomy, and secure distributed quantum computing. Experimental progress on the components for quantum repeaters is moving at a dizzying rate, and theorists have proposed various approaches to managing errors to create high-fidelity quantum entanglement. Building quantum networks presents different challenges from building quantum links. I will give an overview of these issues, then discuss the even more daunting challenge of creating a network of networks -- an internetwork -- and show how our simulations are guiding the design of a true quantum Internet. These challenges include routing (path selection), resource management such as multiplexing techniques, and security considerations within individual networks. Recently, we have discovered that it is possible for a single hijacked quantum repeater to frame other repeaters as malicious, substantially disrupting network operations. All of these issues are magnified when discussing autonomous networks that exchange information, known as an internetwork. In internetworking, not only is the scale of the problem daunting, but heterogeneous technologies will be deployed and demand interoperability at the logical level as well as the physical. Network operators also prefer to maintain the privacy of their own network operations, requiring mechanisms including connection establishment to operate with minimal sharing of information across network boundaries.
Quantum mechanics shows that if one is able to generate and manipulate entanglement over a distance, one is able to perform certain tasks which are impossible using only classical communication. Classical communication refers to what is used in the Internet of today. A quantum internet would therefore bring new capabilities to our highly connected world. These capabilities both involve (1) the ability to perform tasks with are provably impossible in the current Internet, such as unconditionally secure communication, and (2) the ability to perform certain tasks much more efficient, such as distributed (quantum) computing or extending the baseline of telescopes. To be able to build a quantum internet, two main components are needed: (i) hardware that can store, manipulate and entangle qubits and (ii) a software stack to control the hardware. The core task of both of these is to generate entanglement to be used by applications. In this thesis we focus on the latter, i.e. the development of software and protocols that enable entanglement generation using capable hardware. To enable a certain application, one can certainly, in theory, manually specify each operation the hardware should perform, involving micro-wave pulses, lasers etc. However, in practice this is not feasible, if not to say impossible, due to the complexity of the operations needed, especially in a distributed system such as a quantum network. What is needed is a software stack, which can help with abstracting complexity away in multiple layers. This allows for someone to program a protocol in one layer without knowing all the details of the lower layers. In particular, one can abstract away the hardware details, in order to make higher-layer protocols and applications hardware-agnostic. Therefore, to be able to build a universal, efficient and scalable quantum internet, a software stack is crucial. In chapter 2 we start discussing the networking part of a software stack. Namely, we introduce a network stack for a quantum internet, drawing parallels to the IP/TCP-suite of the classical Internet. We continue with proposing a service and interface of the lowest layer of the network stack: the link layer. The link layer is here responsible for generating entanglement between nodes in a quantum network which are directly connected by a quantum link, i.e. a fiber cable. When developing a protocol or application it is very useful to be able to run it. Both to see if the intended ideas make sense and also to check that the implementation is actually correct. Currently we do not have quantum hardware that exposes a full-fledge API that can be used to execute applications. For this reason, it is very useful to be able to instead simulate the hardware in a way that exposes the same API as the hardware being developed. In chapter 3 we introduce SimulaQron for this exact purpose. Any application of a quantum internet will need entanglement in one way or another. However, entanglement is generally hard to generate and is usually the bottleneck when executing an application. We would therefore like to make use of the generated entanglement in the most optimal way. To be able to do this we need to understand how entanglement can be transformed and distributed in a quantum network. We study the entanglement of a particular class of states called graph states in chapters 4 to 9 and how these states can be transformed in a quantum network.
The Internet has revolutionized the way we live. It has enabled applications far beyond what it was originally built for, and it will continue to exceed our expectations for the future. Quantum computers, and the network that will connect them—the Quantum Internet— are likely going to follow the same path. Differently from normal computers, quantum computers can share a property called entanglement, which allows the qubits (quantum bits) to be connected at a much more fundamental level. This property enables a range of new applications that span secure communication to enhanced metrology. Over the past fifteen years, significant progress has been made in connecting rudimentary quantum network nodes via long-distance entanglement. Several quantum platforms have demonstrated entanglement generation between two physically separated qubits. In this thesis we take a significant step forward, both in terms of experimental complexity achieved, and in the abstraction of said complexity for future developments. Moving past two-node experiments required a fundamental redesign of our experimental apparatus, as well as developing the capabilities to control simultaneously the additional node. The first result of this thesis is building a three-node entanglement-based quantum network. We demonstrated distribution of Greenberger-Horne-Zeilinger states over the network, as well as a building block for larger networks: entanglement swapping. Differently from previous multi-node demonstrations, which relied on post-selection, our network is able to perform the entanglement distribution in a heralded fashion: a signal will notify the users that the protocol was successful, and that the state is ready to be used. The second result builds on the first, by adding control over a fifth qubit, improving the quality of the entanglement, and introducing a novel repetitive readout technique, to achieve quantum teleportation of a qubit from the third node to the first—nodes that do not share a direct entanglement channel. The third and final result is the demonstration of entanglement delivery using a quantum network stack. The Internet is built using a plethora of physical platforms: optical fibers, Ethernet cables, Wi-Fi, satellite signals etc. To abstract their functionality, and make applications work regardless of the underlying platform, a layered approach was developed in the 1970s (the Internet protocol). Taking inspiration from classical network stacks, we demonstrate the first two layers of a quantum network stack, the physical layer (where the qubits, lasers and signal generators live), and the link layer, which abstracts the concepts of qubit and entanglement generation such that they can be used by applications at the higher-layers, hiding the complexity of the quantum platform being used.