Researchers working there have managed to transmit quantum bits (qubits) over 600 kilometers of fiber optics while managing to preserve the fragile quantum data encoded in the particles. Led by Cambridge-based Toshiba researchers, the project, published in the journal Nature Photonic, claims it will help facilitate the creation of the next-generation quantum internet. Quantum Internet is described as a network for quantum devices to exchange information, which, among other benefits, will improve the security of communications to essentially create a non-hackable transmission, using quantum cryptography. The Toshiba researchers' record distance effort was made possible by new technology that stabilizes environmental fluctuations in fiber optic cables. Dubbed dual-band stabilization, the method involves sending two signals with different wavelengths, the first of which cancels out rapidly varying jitter in the optical fiber, while the other makes finer adjustments to correct for phase variations.
secure communications
One of the first goals for the application of the new stabilization technique was to carry Quantum Key Distribution (QKD), which is a secure communication protocol that exploits security keys based on the laws of physics rather than mathematical complexity. The researchers note that commercial QKD systems are limited to around 100 to 200 km of fiber. Toshiba came up with the Twin Field QKD protocol as a way to extend the distance in 2018, and finally with the dual-band stabilization technique, its researchers have now implemented Twin Field QKD for hundreds of kilometers. "With the new techniques we have developed, even further extensions of the communication distance for QKD are possible and our solutions can also be applied to other quantum communication protocols and applications," said Mirko Pittaluga, one of the Toshiba researchers who worked on in the project. . The sources said the company hopes the new technique can be used to create secure communication links between cities such as London, Paris, Brussels, Amsterdam and Dublin. via ZDNet