Toshiba Demonstrates Breakthrough in Long-distance Quantum Communications

Toshiba’s Cambridge Research Laboratory demonstrated quantum communications over optical fibers exceeding 600 km in length. The work leverages a technique called dual-band stabilization, and it marks a significant advance in quantum-encrypted communication, particularly for the secure transfer of information between metropolitan areas. How to transmit quantum bits over long optical fibers is among the challenges in building a quantum internet; small changes in ambient conditions, such as fluctuations in temperature, cause the fibers to expand and contract. This scrambles the fragile qubits encoded as a phase delay of a weak optical pulse in the fiber. Diagram describing Toshiba’s dual-band stabilization method for...