The use of quantum satellites can be significant paving the way for novel telecommunications network paradigms, making it possible to connect remote regions. Given the rapid development of quantum communication technologies, many studies are focusing on quantum satellites interconnections via Free Space Optic (FSO), especially considering that the adoption of wired alternatives did not achieve significant results, mainly in terms of covering long distances. In this context, the global interconnection of Quantum Computers (QCs) through the so-called Quantum Internet (QI) compels for new communications and computing architectures such as Quantum Cloud (QCloud). To this purpose, the deployment of Satellite Quantum Networks (SQNs) could make easily available innovative services spanning from security to advanced computing, especially by using Software-Defined Networking (SDN) technology, which is considered a significant enabler for the management of SQNs. Moreover, considering the rapid variability of the topology in terms of nodes and links features, the paper proposes a specific Temporal Networks (TNs) optimization strategy embedded in an SDN Controller ecosystem, dynamically optimizing the path durations to achieve the highest entanglement rate, while limiting the disconnections. Performance evaluation in a worst case scenario shows that the proposed framework is able to support distributed applications by exploiting all the connection opportunities.
The use of quantum satellites can be significant paving the way for novel telecommunications network paradigms, making it possible to connect remote regions. Given the rapid development of quantum communication technologies, many studies are focusing on quantum satellites interconnections via Free Space Optic (FSO), especially considering that the adoption of wired alternatives did not achieve significant results, mainly in terms of covering long distances. In this context, the global interconnection of Quantum Computers (QCs) through the so-called Quantum Internet (QI) compels for new communications and computing architectures such as Quantum Cloud (QCloud). To this purpose, the deployment of Satellite Quantum Networks (SQNs) could make easily available innovative services spanning from security to advanced computing, especially by using Software-Defined Networking (SDN) technology, which is considered a significant enabler for the management of SQNs. Moreover, considering the rapid variability of the topology in terms of nodes and links features, the paper proposes a specific Temporal Networks (TNs) optimization strategy embedded in an SDN Controller ecosystem, dynamically optimizing the path durations to achieve the highest entanglement rate, while limiting the disconnections. Performance evaluation in a worst case scenario shows that the proposed framework is able to support distributed applications by exploiting all the connection opportunities.
Recently, quantum computing and communications rapidly developed to interconnect heterogeneous quantum devices. In particular, some researchers have been performed about terrestrial quantum communications over typical optical fiber links. However, this technology is affected by extremely high losses that can be faced only through the deployment of several repeaters, which in turn involve impractical costs for end-to-end (E2E) route management. Quantum Satellite Networks (QSNs) can overcome the limitations of terrestrial optical networks, such as a remarkable signal attenuation over long distances and difficulty of intercontinental communications. The recent studies on quantum satellite communications motivated our research towards a Low Earth Orbit (LEO) quantum satellite backbone for interconnecting quantum on Earth Servers in order to achieve an unprecedented computational capacity. Specifically, our paper proposes a near optimum E2E path evaluation procedure allowing an efficient switching in order to maximize the entanglement generation rate. Indeed, this is one of the main issues that involve the Data Link Layer and the Network Layer of the Quantum Internet (QI) protocol stack, which is in its early standardization phase. In particular, the design of our approach is based on the Software-Defined Networking (SDN) paradigm with the aim of minimizing the number of hops for E2E connection and maximizing network capacity. Therefore, we compare distributed and centralized approaches in order to achieve a trade-off between performance and cost.
Satellites and aerial platforms can be significant in the development of new telecommunications networks, allowing to deploy networks with extremely high performance even in remote areas. Recently, considering the development of quantum communication technologies, many studies are concentrated on Free Space Optic (FSO) Non-Terrestrial links, also considering that the studies performed so far on Optical Fibers (OFs) have not pointed out significant results, especially in terms of coverage. Moreover, the decrease of launch costs and the use of new satellite technologies such as CubeSats make the deployment of satellite constellations affordable. Thanks to the deployment of Non-Terrestrial Quantum Networks (NTQNs), the novel services offered by the Quantum Internet (QI) could be made easily accessible to all. In particular, Quantum Computers (QCs) can perform beyond the capabilities of any classical processor, and the interconnection of these devices on a global scale makes it possible to achieve extremely high computational capabilities, thus opening the way to new applications, such as Quantum Cloud (QCloud). Therefore, the recent studies in this area motivate this survey, which in addition to providing some base concept of quantum information, describes the current technologies needed to create quantum NT backbones. Specifically, this survey examines some studies over the period 2010–2023, which are related to the realization of quantum communications using satellites and other aerial platforms such as High Altitude Platforms (HAPS) and quantum drones. Some of the architectures that are described in this survey make use of the Software-Defined Networking (SDN) paradigm, which can be envisaged as a key enabler for the management of heterogeneous QNs in general. Furthermore, through the description of various experiments, the paper shows the applications that can be enabled by the future quantum NT backbones. In particular, in addition to improving the security of current systems through the Quantum Key Distribution (QKD), it could be possible to interconnect clusters of QCs over long distances and create extremely reliable positioning systems. Finally, the paper outlines some possible future developments.
The creation of the future quantum Internet requires the development of new systems, architectures, and communications protocols. As a matter of fact, the optical fiber technology is affected by extremely high losses; thus, the deployment of a quantum satellite network (QSN) composed of quantum satellite repeaters (QSRs) in low Earth orbit would make it possible to overcome these attenuation problems. For these reasons, we consider the design of an ad hoc quantum satellite backbone based on the Software-Defined Networking (SDN) paradigm with a modular two-tier Control Plane (CP). The first tier of the CP is embedded into a Master Control Station (MCS) on the ground, which coordinates the entire constellation and performs the management of the CP integrated into the constellation itself. This second tier is responsible for entanglement generation and management on the selected path. In addition to defining the SDN architecture in all its components, we present a possible protocol to generate entanglement on the end-to-end (E2E) path. Furthermore, we evaluate the performance of the developed protocol in terms of the latency required to establish entanglement between two ground stations connected via the quantum satellite backbone.
Swarms of drones are utilized in a wide range of applications, considering that they can be deployed on-demand and are economically affordable. Furthermore, they can also have a significant role in the creation of future Quantum Networks (QNs). As a matter of fact, the use of drones allows deploying a non terrestrial Quantum Metropolitan Area Network (QMAN), overcoming Optical Fibers’ (OFs) limits, due to the large percentage of photons that scatters before reaching the receiver. However, random fluctuations of drones’ positions and atmospheric turbulence can affect the quality of the Free Space Optic (FSO) link with a significant impact on performance. Considering that Quantum Drone Networks (QDNs) require significant control, Software-Defined Networking (SDN) paradigm can play a key role in their provisioning. Specifically, an SDN Controller is responsible for managing the global strategies for the distribution of end-to-end (E2E) entangled pairs. Therefore, this paper provides the design of an SDN-based architecture for supporting high-performance Metropolitan Quantum Drone Networks (MQDNs) with a specific protocol for creating entanglement between two Ground Stations (GSs) through the swarm of drones. The proposed architecture can be employed for distributed quantum computing applications and entanglement-based Quantum Key Distribution (QKD) services. Moreover, a suited objective function to optimize the planning and operation of the swarm mission has been proposed. Finally, the paper provides a performance evaluation considering the most relevant metrics, such as fidelity, entanglement rate, and the overhead of the proposed protocol, pointing out that even higher performance than OFs is achievable.
The interconnection of quantum computers through the so-called Quantum Internet is a very promising approach. The most critical issues concern the physical layer, considering that the creation of entanglement over long distances is still problematic. Given the difficulty that usually arises from fiber optics due to exponential losses, the introduction of intermediate quantum repeaters (QRs) allows mitigating the problem. A quantum satellite network based on QRs on satellites deployed over low Earth orbit could make it possible to overcome the constraints of terrestrial optical networks. Hence, the recent technological developments in terms of quantum satellite communications motivated our investigation on an ad hoc quantum satellite backbone design based on the software defined networking paradigm with a control plane directly integrated into the constellation itself. Our aim is to outline some guidelines by comparing several options. Specifically, the focus is to analyze different architectural solutions making some considerations on their feasibility, possible benefits, and costs. Finally, we performed some simulations on the architectures we considered the most promising, concluding that the integration of the control plane in the constellation itself is the most appropriate solution.
The great scientific and technological advances that are being carried out in the field of quantum communications, accompanied by large investment programs such as EuroQCI, are driving the deployment of quantum network throughout the world. One of the final long-term objectives is to achieve the development of a quantum internet that provides greater security in its services and new functionalities that the current internet does not have. This article analyzes the possible integration strategies of already deployed networks or in the process of being deployed in order to reach a future global quantum network. Two strategies based on the SDN paradigm are proposed, based on a hierarchical controller scheme and on a distributed model. Each of these approaches shows pros and cons and could be applicable in different use cases. To define these strategies, the most relevant deployments of quantum communications networks carried out to date has been analyzed, as well as the different approaches for a quantum network architecture and topology, and the various proposed definitions of what quantum internet is and what are the components that would make it up in an ideal scenario. Finally, several detected opportunities and challenges regarding security and technological aspects are presented.