Japan switches on its first full-stack neutral-atom quantum computer

New machine uses individual atoms held in place by lasers and will grow from around 50 qubits to 500 as researchers work towards more practical quantum computing

Japan has today switched on its first full-stack neutral-atom quantum computer, using individual atoms and lasers in an attempt to overcome some of the problems that have so far limited the technology’s practical use.

The system, named Shunkai, has been developed by the Institute for Molecular Science in Okazaki (IMS) and will initially use around 50 qubits – the basic units of information used by a quantum computer – before expanding to approximately 500.

Unlike an ordinary computer, which processes information using conventional electronic bits, Shunkai uses individual atoms as its qubits. 

The atoms are held in position by tightly focused laser beams known as optical tweezers and calculations are carried out by exposing them to microwaves or laser light.

The neutral-atom approach can operate at room temperature without a refrigerator and allows atoms to be moved during calculations. Researchers say it should also be relatively easy to increase the number of qubits and arrange them differently depending on the calculation being performed.

Shunkai is described as “full-stack” because it brings together all the layers needed to turn a user’s instructions into operations carried out by the quantum hardware and then produce a result. 

IMS led development of the system, working with Hitachi on its software and U.S quantum technology company Infleqtion on its quantum processing unit.

Parts of Shunkai will be opened to outside researchers and companies to develop applications and test ways of detecting and correcting errors – one of the major obstacles to making quantum computers reliable enough for widespread practical use.

The wider research project aims to develop a fault-tolerant neutral-atom quantum computer with 10,000 physical qubits, quantum error detection and correction and access for external users by March 2031.

Professor Kenji Ohmori, who leads the project, said: “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 added: “We expect that the external use of our full-stack machine Shunkai, for example, by the theory and software researchers for the development of error-correction technologies, and by the corporate researchers toward practical applications would lead to ripple effects on various fields in industry, academia and government around the world.”

Shunkai takes its name from Edo-period astronomer Harumi Shibukawa, whose given name can also be pronounced Shunkai and who developed Japan’s first indigenous calendar system.

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_{Main image: Shunkai, Japan’s first full-stack neutral-atom quantum computer, developed by the Institute for Molecular Science in Okazaki. The machine uses individual atoms held and controlled with laser light to perform quantum calculations. Credit: Takafumi Tomita / Institute for Molecular Science}