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.
One promising technique for working toward practical photonic quantum technologies is to implement multiple operations on a monolithic chip, thereby improving stability, scalability and miniaturization. The on-chip spatial control of entangled photons will certainly benefi t numerous applications, including quantum imaging, quantum lithography, quantum metrology and quantum computation. However, external optical elements are usually required to spatially control the entangled photons. Here we present the fi rst experimental demonstration of on-chip spatial control of entangled photons, based on a domain-engineered nonlinear photonic crystal. We manipulate the entangled photons using the inherent properties of the crystal during the parametric downconversion, demonstrating two-photon focusing and beam-splitting from a periodically poled lithium tantalate crystal with a parabolic phase profi le. These experimental results indicate that versatile and precise spatial control of entangled photons is achievable. Because they may be operated independent of any bulk optical elements, domain-engineered nonlinear photonic crystals may prove to be a valuable ingredient in on-chip integrated quantum optics.
scite is a Brooklyn-based organization that helps researchers better discover and understand research articles through Smart Citations–citations that display the context of the citation and describe whether the article provides supporting or contrasting evidence. scite is used by students and researchers from around the world and is funded in part by the National Science Foundation and the National Institute on Drug Abuse of the National Institutes of Health.