Oxford Quantum Circuits (OQC) is a UK-based quantum computing company building superconducting quantum computers for enterprise, government and research use. Founded out of Oxford by Dr Peter Leek, Founder and Chief Scientific Officer, and now led by CEO Gerald Mullally, OQC was Europe's first Quantum-Compute-as-a-Service (QCaaS) provider and remains the only company deploying quantum systems directly into commercial data centres rather than standalone lab environments.

OQC's architecture uses superconducting transmon qubits on sapphire substrates, with a proprietary coaxial circuit design that reduces crosstalk and simplifies wiring inside cryogenic refrigerators. The company holds the record for the fastest benchmarked two-qubit gate at 25 nanoseconds, and achieves a 1:1 physical-to-logical qubit ratio, far ahead of competitors needing tens or hundreds of physical qubits per logical qubit. Rather than selling hardware outright, OQC deploys systems inside partner data centres run by Equinix and Digital Realty, with live deployments in the UK, US, Japan and Spain.

Headquartered in London, OQC closed an oversubscribed £260 million ($350 million) Series C in June 2026, the largest private funding round ever raised by a quantum computing company in Europe. The round was led by Bullhound Capital, with participation from the British Business Bank, Chevron, Oxford Science Enterprises and Firgun Ventures, positioning OQC as one of the best-capitalised private quantum computing companies in the world.