Glass-Based Quantum Chip Enables High-Speed Secure Communication
Researchers from the University of Padua, Politecnico di Milano, and the CNR Institute for Photonics and Nanotechnologies have developed a novel quantum communication device using borosilicate glass. Reported in Advanced Photonics, the team created a high-performance, laser-written quantum coherent receiver directly inside the glass. Unlike traditional silicon-based receivers, this glass-based system offers low optical loss, polarization independence, and long-term stability, making it compatible with existing fiber-optic networks. The chip integrates tunable heterodyne detection, beam splitters, thermo-optic phase shifters, and three-dimensional waveguides to enable precise measurement of quantum signals. This versatility allows the same device to function as both a quantum random number generator (QRNG) and a continuous-variable quantum key distribution (CV-QKD) system. The QRNG achieved a record-secure random bit generation rate of 42.7 Gbit/s, while the CV-QKD system delivered a 3.2 Mbit/s secret key rate over a simulated 9.3-km fiber link. The study highlights additional benefits of glass, including environmental resilience, low-loss fiber coupling, and cost-effective fabrication via femtosecond laser writing. These properties make glass-based photonics a promising platform for scaling quantum communication beyond laboratory setups to practical, real-world networks, including potential space applications. This approach represents a significant step toward robust, high-speed quantum security technology.
