The quantum satellite is a cornerstone towards practical free-space quantum network and overcomes the photon loss over large distance. However, challenges still exist including real-time all-location coverage and multi-node construction, which may be complemented by the diversity of modern drones. Here we demonstrate the first drone-based entanglement distribution at all-weather conditions over 200 meters (test field limited), and the Clauser-Horne-Shimony-Holt S-parameter exceeds 2.49, within 35 kg take-off weight. With symmetric transmitter and receiver beam apertures and single-mode-fiber-coupling technology, such progress is ready for future quantum network with multi-node expansion. This network can be further integrated in picture-drone sizes for plug-and-play local-area coverage, or loaded onto high-altitude drones for wide-area coverage, which adds flexibility while connecting to the existing satellites and ground fiber-based quantum network.
The quantum satellite is a cornerstone towards practical free-space quantum network and overcomes the photon loss over large distance. However, challenges still exist including real-time all-location coverage and multi-node construction, which may be complemented by the diversity of modern drones. Here we demonstrate the first drone-based entanglement distribution at all-weather conditions over 200 meters (test field limited), and the Clauser-Horne-Shimony-Holt S-parameter exceeds 2.49, within 35 kg take-off weight. With symmetric transmitter and receiver beam apertures and single-mode-fiber-coupling technology, such progress is ready for future quantum network with multi-node expansion. This network can be further integrated in picture-drone sizes for plug-and-play local-area coverage, or loaded onto high-altitude drones for wide-area coverage, which adds flexibility while connecting to the existing satellites and ground fiber-based quantum network.
Satellites have shown free-space quantum-communication ability; however, they are orbit-limited from full-time all-location coverage. Meanwhile, practical quantum networks require satellite constellations, which are complicated and expensive, whereas the airborne mobile quantum communication may be a practical alternative to offering full-time all-location multi-weather coverage in a cost-effective way. Here, we demonstrate the first mobile entanglement distribution based on drones, realizing multi-weather operation including daytime and rainy nights, with a Clauser-Horne-Shimony-Holt S-parameter measured to be 2.41 ± 0.14 and 2.49 ± 0.06, respectively. Such a system shows unparalleled mobility, flexibility and reconfigurability compared to the existing satellite and fiber-based quantum communication, and reveals its potential to establish a multinode quantum network, with a scalable design using symmetrical lens diameter and single-mode-fiber coupling. All key technologies have been developed to pack quantum nodes into lightweight mobile platforms for local-area coverage, and arouse further technical improvements to establish wide-area quantum networks with high-altitude mobile communication.
Entanglement distribution has been accomplished using a flying drone, and this mobile platform can be generalized for multiple mobile nodes with optical relay among them. Here we develop the first optical relay to reshape the wave front of photons for their low diffraction loss in free-space transmission. Using two drones, where one distributes the entangled photons and the other serves as relay node, we achieve entanglement distribution with Clauser-Horne-Shimony-Holt S parameter of 2.59±0.11 at 1 km distance. Key components for entangled source, tracking, and relay are developed with high performance and are lightweight, constructing a scalable airborne system for multinode connectio and toward mobile quantum networks.
Drone-based entanglement distribution provides full spatiotemporal coverage for quantum networks, enabling quantum key distribution (QKD) in dynamic environments. The security of QKD fundamentally depends on high-fidelity quantum state measurements, for which high-precision clock synchronization is indispensable, as timing jitter is inversely correlated with quantum state fidelity. However, drone-based clock synchronization is constrained by SWaP (Size, Weight, and Power) limitations and dynamic mobility effects. Here, we propose a synchronization protocol for drone-based entanglement distribution, leveraging nanosecond-accurate Global Navigation Satellite System (GNSS) timing and entanglement-based timing correction to overcome SWaP constraints. Experimental results demonstrate 24 ps RMS synchronization in simulated free-space quantum channels with distance dynamics, without requiring precision reference clock. Our protocol enables drone-based entanglement distribution, paving the way for seamless wide-area and local-area quantum internet.
The quantum Internet is profoundly impacting the world and is expected to be operational in the future. With the global wide-area quantum networks begin to take shape, drone-based quantum entanglement networks have attracted widespread attention. Compared to quantum links based on optical fibers or satellites, drone-based quantum entanglement networks can effectively address the need for responsive and on-demand quantum network coverage across diverse locations and operational times. To realize network construction, entanglement routing protocols pose a significant challenge. On the one hand, the fidelity of the entangled system degrades hop-byhop. On the other hand, the dynamics and limited energy of drone nodes are equally not negligible. However, existing works have not adequately addressed these issues. In this paper, we present a novel fidelity-guaranteed entanglement routing protocol for drone-based quantum networks (FGER_D). The FGER_D considers the node energy and quantum link vulnerability comprehensively, selects end-to-end fidelity as the routing metric, and employs multiple attempts' entanglement purification scheme to provide fidelity-guaranteed entanglement connections in noisy environments. Numerical simulations demonstrate that compared to existing algorithms, FGER_D improves network throughput by approximately 24% under default settings, while also ensuring network fidelity and extending network lifetime. Our work is expected to provide a theoretical basis for the deployment of drone-based entanglement distribution networks.
Global quantum networks for secure communication can be realized using large fleets of satellites distributing entangled photon pairs between ground-based nodes. Because the cost of a satellite depends on its size, the smallest satellites will be most cost-effective. This Letter describes a miniaturized, polarization entangled, photon-pair source operating on board a nano-satellite. The source violates Bell’s inequality with a Clauser–Horne–Shimony–Holt parameter of 2.60 ± 0.06 . This source can be combined with optical link technologies to enable future quantum communication nano-satellite missions.
The rapid advancement of quantum physical devices is transforming the quantum Internet from theory to practice. To achieve the envisioned full-time and all-location coverage, mobile quantum networks using drones have been proposed as a critical supplement to existing fiber and satellite quantum links, especially in scenarios where traditional optical links are unavailable. Although experiments in drone-based entanglement distribution have been successfully conducted, the field currently lacks a systematic network architecture and a dedicated protocol stack to integrate drone nodes and coordinate complex network functions efficiently. To address this gap, we propose a comprehensive design framework for drone-based quantum entanglement networks. First, we introduce a hierarchical architecture consisting of a quantum backbone relay network and quantum local area access networks. Second, for the local networks, we develop a clustering model based on the classical-quantum combinatorial metric to dynamically select and manage cluster heads. Third, we design a layered protocol stack that modularizes the end-to-end quantum information transmission process into well-defined functional layers. Subsequently, based on this architecture and protocol stack, we present the integrated design of a quantum drone node. Finally, we evaluate the designed network architecture. The results demonstrate that the proposed framework can significantly reduce the network overhead and improve the end-to-end entanglement distribution rate. Our work lays the foundation for the scalable development of mobile quantum networks.