zerothird GmbH

The security of digital communications rests on mathematical problems that today's computers find practically impossible to solve. Public-key cryptography — the foundation of secure connections across the internet, from banking to government communications — is built on that computational intractability. But the arrival of sufficiently powerful quantum computers will eventually overturn that foundation, and the cybersecurity community has known for years that the window for preparing an adequate response is finite. Quantum key distribution provides a solution grounded in the laws of physics rather than in the hardness of a mathematical problem, making it unconditionally secure against any adversary regardless of their computational capability — present or future. zerothird GmbH has developed an integrated QKD system specifically designed for inter-city distances of approximately 10 kilometres — a deployment range that represents one of the most commercially relevant and technically tractable scenarios for quantum-secure communications in metropolitan environments. At this scale, the technology is directly applicable to connecting data centres, financial district offices, government facilities, and other security-critical sites within a city through dedicated quantum-secured fibre links. The system uses polarisation-entangled photon pairs — a particularly robust QKD approach that leverages the fundamental correlations of quantum entanglement to generate encryption keys whose security is guaranteed by physics. Any attempt to intercept the key material disturbs the quantum states of the photons in ways that are immediately detectable, alerting the communicating parties to the eavesdropping attempt before any information is compromised. This is the core physical guarantee that distinguishes QKD from conventional cryptography: security that does not depend on assumptions about an adversary's computational resources. The company's founding team brings exceptional depth of experience to the engineering challenges of making this technology manufacturable and deployable in real-world environments. Thomas Heine, co-founder and development and production lead, brings nine years of R&D and manufacturing leadership at XARION — a company focused on ultrasound sensors and optical microphones — and eleven years at TOPTICA Photonics working on the development of miniaturised laser technology for quantum applications. This combination of precision optical engineering and quantum technology expertise is rare and practically significant: building QKD hardware that performs reliably outside a laboratory, in real infrastructure environments, with the robustness and repeatability that commercial deployment demands, is a substantially harder engineering problem than demonstrating the physics in a controlled setting. zerothird's growth strategy is built on partnerships and security operations ecosystem development, working with telecommunications providers, data centre operators, financial institutions, and government agencies whose communications security requirements make quantum-secured links not just desirable but eventually essential.