Microlaser chip adds new dimensions to quantum communication

https://phys.org/news/2022-11-microlaser-chip-dimensions-quantum-communication.html

"device's four-level qudits enable significant advances in quantum cryptography, raising the maximum secrete key rate for information exchange from 1 bit per pulse to 2 bits per pulse. The device offers four levels of superposition and opens the door to further increases in dimension... on a single chip"