Japan's First Full-Stack Neutral-Atom Quantum Computer Goes Live

Japan's Institute for Molecular Science (IMS) announced on August 24 that it has begun operating "Shunkai," the country's first full-stack neutral-atom quantum computer. The system was built by a team led by Professor Kenji Ohmori under the Cabinet Office and Japan Science and Technology Agency's Moonshot Research and Development Program, with Hitachi developing the software layer and Infleqtion building the quantum processing hardware.

Neutral-atom quantum computers use single atoms, held in place by tightly focused lasers called optical tweezers, as qubits, the basic units of quantum information. Microwaves or laser light drive the calculations, and a camera reads out the results by observing fluorescence from each atom. The approach works at room temperature, without a refrigerator, and researchers can move the trapped atoms during a calculation to link qubits together.

A "full-stack" system integrates every layer needed to turn a user's input into the signals that drive the hardware, similar to how a personal computer combines hardware and software. Shunkai starts with about 50 qubits and is expected to scale to roughly 500, with parts of the system opened to outside researchers to develop applications and to test and improve quantum error correction, a set of techniques for detecting and fixing mistakes in fragile quantum computations.

The system is named after Harumi Shibukawa, an Edo-period astronomer whose given name is also read "Shunkai," who created Japan's first original calendar system through precise calculations of celestial motion. The Moonshot project's second stage, which began in April 2026, aims to expand Shunkai to 10,000 physical qubits with quantum error detection and correction by March 2031, and to make the system available to external users.