Quantum computing with Diamond spin

A modular architecture scalable through optical connections

Research and development in quantum computing is advancing rapidly, but scaling up remains a major hurdle to widespread adoption in society. Diamond spin is a new approach designed for scalability through optical connections.

[Latest Update]
Fujitsu develops diamond-spin quantum computer prototype (September 8, 2026)

Fujitsu has developed a prototype of an optically scalable diamond spin-based quantum computer using SnV centers as qubits. This represents a significant milestone toward scaling up quantum computers.

Features of the diamond spin quantum computer

The two types of qubits that make up the module

Diamond spin-based quantum computers use spins formed by defect structures in synthetic diamond known as “color centers” as qubits. The electron spins of these color centers are used as “electron spin qubits”, which can be connected optically with other qubits. Together with “nuclear spin qubits”, which can stably preserve quantum states, they form a single quantum module. Note that nitrogen is generally used as the impurity for color centers, and such structures are called NV centers.

Scalability via optical interconnects

One of the key features of the diamond spin-based approach is its ability to be flexibly interconnected using light. Since these systems utilize quantum modules designed for optical interconnection, once a basic module is established, scaling up to larger systems becomes possible using light. This characteristic is extremely important in enabling the large-scale scalability essential for future practical use.

Modular architectures with optical interconnection, enabling scale beyond hardware boundaries

Behind the Development of Diamond Spin (Technology News)

Long coherence times

Another key feature of the diamond spin-based approach is its long coherence time, which allows quantum states and quantum information to be handled stably, making it an important factor in advancing toward more practical quantum computing.

What is the diamond Spin Method? (Technology News)

Potential for heterogeneous architectures

In addition to functioning as a computing platform, diamond spin-based quantum computers have the potential, through their optical connectivity, to be physically connected in the future with quantum computers based on other approaches, such as superconducting systems. This makes it possible to realize quantum computing systems that combine different types of quantum computers into a heterogeneous architecture.

Heterogeneous architecture quantum computer

SnV centers for enhancing optical connection efficiency

Traditionally, nitrogen-vacancy (NV) centers, created by doping diamond with nitrogen, have been widely used. In the diamond spin approach that Fujitsu has developed, however, tin-vacancy (SnV) centers, created by doping diamond with tin, are employed. SnV centers are less susceptible to external noise and emit light at approximately ten times the brightness of conventional NV centers, thereby enhancing the efficiency of optical connections. Going forward, it will be possible to scale up systems by connecting multiple quantum modules using SnV centers through high-efficiency optical connections.

Frequently Asked Questions

Q. What is the diamond spin method?

A. The diamond spin method uses the electron spins of color centers in diamond crystals and the nuclear spins coupled to them as qubits. Its modular architecture, designed for optical interconnection, enables scalable quantum computing.

Q. How does “optical connection” address the challenge of scaling up?

A. In the diamond spin method, electron spin qubits can be connected using light. By employing quantum modules designed for optical interconnection, multiple quantum modules can be flexibly interconnected, enabling scalable quantum computing.

Q. Under what framework was Fujitsu’s diamond spin quantum computer developed?

A. Fujitsu’s diamond spin quantum computer is being developed through a joint research collaboration between Fujitsu, Delft University of Technology, and QuTech, a quantum technology research institute, with all technologies required for quantum computers being developed as a full stack.

Q. Why is Fujitsu working on both superconducting and diamond spin approaches?

A. Fujitsu positions the superconducting approach, where research is more advanced, as the technology that will drive the near-term practical realization of quantum computing, while at the same time pursuing research on the diamond spin approach, which offers scalability through optical connectivity. Going forward, Fujitsu will continue to advance and scale the diamond spin approach through optical connectivity. In parallel, the company will develop technologies that integrate diamond spin and superconducting systems, with the goal of realizing quantum computers that leverage the strengths of both technologies.

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