C12 Quantum Electronics is a deep-tech company that designs and builds scalable, fault-tolerant quantum computers using carbon-based technology. Spun out of the Physics Laboratory of the École Normale Supérieure in Paris, the company utilizes ultra-pure carbon nanotubes as the fundamental building blocks of its quantum processors to minimize error rates and overcome the scalability issues associated with silicon-based alternatives.

Alongside its proprietary hardware development, C12 provides advanced quantum development tools such as Callisto, a quantum emulator grounded in carbon nanotube physics that allows developers to design and refine quantum algorithms. The company operates a dedicated quantum fabrication facility in Paris and collaborates with leading aerospace, defense, and industrial enterprises to deliver high-fidelity quantum processors for complex optimization, simulation, and real-time tracking applications.