Researchers from China, Europe, and the US have independently developed new protocols for generating verifiable quantum entanglement between distant nodes, potentially advancing the creation of a quantum Internet. These protocols involve using atomic ensembles and solid-state quantum memories to entangle qubits over city-sized networks. Despite the progress, some experts remain skeptical about the practical implications for building large-scale quantum computers.
Researchers at Princeton University have developed a new method for constructing quantum repeaters using telecom-ready light emitted from a single ion implanted in a crystal, with calcium tungstate identified as the optimal material. This innovative atomic device enables the transmission of high-fidelity quantum information over fiber optic networks, simplifying the connection of quantum computers over long distances. The device design utilizes a calcium tungstate crystal doped with erbium ions and a nanoscopic piece of silicon to guide individual photons into the fiber optic cable. The researchers demonstrated the suitability of the new material by proving the emission of indistinguishable photons, a crucial factor for quantum networks. Further work is needed to improve the storage time of quantum states in the erbium ion's spin.
