Japan’s first operational full-stack neutral-atom quantum computer, which packs approximately 50 qubits at launch and could eventually reach 500, has just been switched on.

Called Shunkai, the system was designed by a research team led by Kenji Ohmori, PhD, a chemist and a renowned Japanese professor at the Institute for Molecular Science (IMS), part of Japan’s National Institutes of Natural Sciences. The machine officially went live on August 24.

Shunkai is powered by a quantum processing unit (QPU) supplied by Colorado-based quantum technology company Infleqtion. The company was also the only foreign quantum partner selected by the Japan Science and Technology Agency (JST) for its Quantum Moonshot program.

The program is a Japanese government effort aimed at developing fault-tolerant universal quantum computers by the year 2050. “This milestone marks a pivotal moment for Japan’s quantum ambitions as well as Infleqtion’s role in advancing production-ready quantum platforms at scale,” Pranav Gokhale, Infleqtion CTO, pointed out.

Japan’s quantum ambitions

According to Infleqtion, Shunkai will initially run with 50 qubits before expanding to around 500 as development progresses. Neutral-atom quantum computers use individual atoms as qubits, the basic units of quantum information.

They can run at room temperature without large refrigeration systems. Also, the atoms can be trapped and manipulated with precisely controlled laser light. This allows scientists to connect different qubits and also tailor their layout to specific algorithms.

Because neutral atoms can be arranged in large arrays while maintaining precise control over their quantum states, the technology is considered a promising route toward much larger quantum computers. It could make it easier for engineers to build computers with more qubits while preserving quantum information.

Infleqtion shared that its QPU helped the Japanese team move from research and development toward an operational full-stack computing platform. “Our quantum processing unit delivers the programmability, scalability and fidelity control that next-generation systems demand,” Gokhale explained.

Reaching fault tolerance

Meanwhile, the current launch is not Shunkai’s end. A new phase of the Ohmori Moonshot project began in April 2026. It will focus on improving the computer’s integration, stability and scalability.

The researchers aim to develop a high-performance, fault-tolerant neutral-atom quantum computer with as many as 10,000 physical qubits. “Bringing a full-stack quantum system into production operation is a meaningful step toward fault-tolerant quantum computing that also serves as strong validation of neutral-atom architecture,” Gokhale reported in a press release.

Still, reaching that size alone will not make Shunkai fault-tolerant. The researchers also plan to develop ways to detect and correct errors caused by noise and other disturbances during quantum calculations.

Quantum systems are particularly sensitive to their environments. This means that errors can accumulate during calculations. Error correction seeks to overcome this by using multiple physical qubits to protect the quantum information needed for computation.

The scientists also expect the technology from the project to eventually become available to other external users. This could allow researchers in both, academia and industry, to come up with applications and provide a platform for further work on quantum error correction.

Ohmori said opening Shunkai to outside researchers and companies could help advance error-correction technologies and practical quantum applications while creating wider benefits across industry, academia and government worldwide. “I think it is extremely significant that now we have developed Japan’s first full-stack quantum computer in this cutting-edge modality and started its operation,” he concluded in a statement. The team plans to integrate Shunkai with IMS’s existing shared supercomputer facility to create a hybrid quantum-GPU computing center.