Qudits - 2

A consortium is building a hardware demonstrator to prove that quantum communication systems can work using qudits—quantum states that carry more information than standard qubits—encoded in the twisting patterns of light beams. Today’s quantum communication systems rely on qubits, which are limited to two states (0 or 1). Qudits can encode multiple states simultaneously, potentially carrying far more information per photon. But building practical qudit-based systems requires components that can generate and detect these complex light patterns at standard telecom wavelengths, where existing fibre networks operate. This project addresses that gap by integrating two commercially available UK photonics technologies: photonic crystal surface-emitting lasers (PCSELs) and low-noise avalanche photodiodes (ALDs). If the demonstrator works, it could unlock higher-capacity quantum communication links without requiring new fibre infrastructure. That matters for securing data transmission in critical systems such as energy grids, financial networks, and government communications, where quantum key distribution is already being deployed. The project is an industrial research effort, not fundamental science—it aims to show that a specific set of off-the-shelf components can make qudit-based quantum communication viable.