A team of Chinese scientists has achieved a groundbreaking milestone by creating the world's first memory-memory entanglement within a multi-node quantum network spanning a metropolitan area. This development has significantly extended the practical range of quantum entanglement networks from mere tens of meters to tens of kilometers, marking an enhancement of three orders of magnitude.
This advancement lays a strong foundation for emerging quantum technologies, such as quantum computing and quantum-enhanced long baseline interferometry. Quantum entanglement, a phenomenon where the quantum states of two or more objects are interdependent regardless of the spatial separation between them, is crucial for these technologies.
One of the essential milestones for developing the future quantum internet is moving from simple two-node experiments conducted in laboratories to complex, large-scale multi-node setups. Researchers from the University of Science and Technology of China have made significant progress in this area. They utilized three independent memory nodes, each equipped with atomic ensemble quantum memory, alongside a photonic server that detects single photons to signal successful entanglement generation.
According to the study published in Nature, these memory nodes are separated by a maximum distance of 12.5 kilometers. The research demonstrated that quantum entanglement could be generated simultaneously between any two memory nodes. Notably, the entangled states have a lifetime that exceeds the time required for round-trip communication between these nodes, ensuring stable and reliable entanglement.
This achievement marks the beginning of a new phase in quantum internet research, paving the way for future large-scale quantum networks. The ability to maintain entanglement over such vast distances represents a significant step forward, bringing us closer to the realization of a robust and scalable quantum internet. This work not only demonstrates the feasibility of long-distance quantum networks but also provides a crucial platform for the development of advanced quantum technologies.
