Fujitsu has unveiled the world’s first diamond spin quantum computer prototype, which uses tin-vacancy centers (SnV) embedded in photonic integrated circuits. Announced in September 2026, this prototype marks a significant milestone in the development of modular quantum computing systems. Unlike traditional superconducting quantum computers, which require temperatures near absolute zero (-273.13 °C), this new device operates at a slightly higher but still extremely cold temperature of -271.6 °C. This allows for more practical and scalable applications in the future. The prototype utilizes light to connect multiple quantum modules, enabling entanglement between distant quantum bits, or qubits. Fujitsu has also developed a software platform called the Fujitsu Hybrid Quantum Computing Platform, which offers the necessary tools for users without requiring specialized knowledge of quantum mechanics. This platform aims to make quantum computing more accessible to researchers and developers. A key innovation in the prototype is the use of tin-vacancy centers within diamond. These are defects in the diamond's crystal structure created by inserting a tin atom between two vacancies. Fujitsu chose tin because it offers superior structural symmetry, making the qubits more stable and less susceptible to external noise. To achieve this, Fujitsu combined cutting-edge techniques such as heterogeneous material linkage, which allows high-quality diamond substrates to be assembled with alumina or silicon dioxide to create ultra-thin chips. An advanced thinning process reduces the diamond’s thickness from several hundred micrometers to just a few hundred nanometers, enabling more precise control of the quantum states. The prototype also integrates nanometer-sized diamond crystals with SnV centers into alumina optical waveguides, which are transparent to visible light. This allows for the extraction of single photons emitted during the reading of qubits. Fujitsu collaborated with the University of Tokyo to develop the complex machining of diamond required for this process. Additionally, the company has created a new mechanism to convert quantum circuits, translating standard quantum gates into sequences of control signals using light, microwaves, and radio waves. This breakthrough is the result of joint research since 2020 with Delft University of Technology and QuTech. Looking ahead, Fujitsu plans to develop a new prototype with multiple interconnected modules by 2027. The company also aims to explore hybrid technologies that combine this diamond spin approach with superconducting quantum computing. Fujitsu hopes to achieve a quantum system with 250 logical qubits by 2030 and potentially 1,000 qubits by 2035, marking a major leap in quantum computing capabilities.