New photonic quantum architecture combines linear and nonlinear operations in one programmable system

Researchers at Imperial College London and collaborating institutions have developed a programmable photonic quantum processor named Clavina that integrates both linear and nonlinear quantum operations within a single architecture. The work, published in Nature Photonics, addresses a longstanding challenge in photonic quantum computing: photons do not naturally interact, making it difficult to perform the full range of computations required for universal quantum processing.

The Clavina design draws inspiration from classical computer processors, using a central control unit to direct information between a programmable optical network and specialized nonlinear modules. Fast electro-optic modulators switch encoded time bins into different functional modules, allowing the hardware to be reconfigured for different computational tasks without physical redesign. Lead author Dr. Shang Yu, a Marie Skłodowska-Curie Fellow at Imperial, described the architecture as scalable, modular, and extensible.

To test the platform, the team applied Clavina to two complex tasks. First, they simulated the Bose-Hubbard model, a condensed matter physics problem describing interactions between quantum particles. Dr. Jinzhao Sun of Queen Mary University of London noted that the hardware's ability to integrate nonlinear and linear operations enables many-body interaction simulations that are also restricted on superconducting quantum computers.

Second, the researchers demonstrated a far more reliable method for generating Gottesman-Kitaev-Preskill (GKP) states, a critical resource for quantum error correction. Previous photonic approaches produced these states only probabilistically, limiting their practical use. Dr. Raj Patel, UKRI Future Leaders Fellow and leader of Imperial's photonic quantum computing program, said the architecture's nonlinear operations provide a universal gate set at the physical level, which is required for future implementation of bosonic error-correcting codes.

The system also generates other exotic quantum states such as Schrödinger cat states. Co-author Ying Dong of China Jiliang University emphasized that the ability to switch functional modules allows a single hardware set to solve graph problems, simulate quantum systems, or generate large entangled states and resource states for error correction. As quantum computing systems scale, the researchers suggest platforms like Clavina could provide a framework for photonic processors that adapt to new computational challenges without entirely new hardware designs.