• Japan's Institute for Molecular Science has started operating the Shunkai neutral-atom quantum computer
  • Shunkai starts at about 50 qubits and is planned to scale towards 500, while the wider programme targets 10,000 by 2031

The fact

Japan's Institute for Molecular Science has started operating Shunkai, which it describes as the country's first full-stack neutral-atom quantum computer. The system was developed by a team led by Professor Kenji Ohmori under Japan's Moonshot Research and Development Programme. Infleqtion supplied the quantum processing unit, while Hitachi worked with the research team on the software stack.

Shunkai will initially operate with about 50 qubits, with plans to expand towards 500 as development continues. The system holds neutral atoms using optical tweezers created with focused laser light. Lasers and microwaves are used to control the atoms, while cameras detect their quantum states.

A second stage of the Moonshot project began in April 2026. The team will work on system integration, stability and scaling, with a longer-term target of up to 10,000 physical qubits with quantum error detection and correction by March 2031. IMS also plans to make part of the system available to external academic and industry users.

The assessment

Shunkai is now running as a complete system, so the challenge has moved beyond getting the hardware to work. The research team now has to show that the processor, control systems and software can operate together reliably over time.

That will become harder as the machine grows from about 50 qubits towards 500. More atoms have to be controlled and measured accurately, while the electronics and software must handle a much larger system. The longer-term target of 10,000 physical qubits raises the bar again because error detection and correction will also have to work at scale.

For BTW readers, the next test is reliability rather than qubit count alone. Longer operating runs, lower error rates, and successful use by outside researchers will give a clearer picture of how far Shunkai has progressed.

What to watch

Watch when external researchers begin using Shunkai and whether the team publishes uptime, fidelity or error-rate data. Progress from about 50 towards 500 qubits will provide the first major scaling test, while later work on error correction will show how close the project is moving towards its 10,000-physical-qubit goal.