Japan has switched on its first full-stack quantum computer, a machine built from neutral atoms held in place by laser light, and the country’s scientists want to grow it to 10,000 qubits by 2031.
The device, called Shunkai, marks a shift away from the supercooled hardware that defines most quantum systems today. Instead of chilled superconducting circuits, Shunkai traps atoms in a vacuum chamber and suspends them with tightly focused laser beams, a technique known as optical tweezers. Microwaves or laser light then manipulate the atoms’ quantum states, performing calculations that a camera reads by watching each atom glow.
The machine is named after Harumi Shibukawa, a 17th-century Japanese astronomer. Its design promises room-temperature operation, a feature that could make quantum computing far more practical outside the tightly controlled environments where these systems usually live.
The Fragile Building Block
Quantum computers rely on qubits, the quantum version of the classical bit. Unlike a normal bit, which holds a 0 or a 1, a qubit can hold both states at once, a condition called superposition. That property is what gives quantum machines their potential power.
But qubits are fragile. Even a small disturbance from heat, vibration or electromagnetic noise can destabilize them. This fragility is the central problem facing the field.
The error rate in qubits is thought to be roughly 1 in 1,000 operations, compared with around 1 per billion or even 1 per trillion operations in classical computing bits. That difference is why quantum computers need error correction, and why getting a useful system running at scale remains difficult.
How Shunkai Works
Shunkai’s approach is different. Rather than supercooled circuitry, it uses neutral atoms as qubits. These atoms are captured and suspended using optical tweezers, tightly focused laser beams that trap the atoms inside a vacuum chamber.
Microwaves or laser light manipulate the atoms’ quantum states to perform calculations. The results are read by observing the fluorescence from each individual atom with a camera. Because the arrangement of qubits in neutral-atom systems can be fine-tuned during calculations, researchers can adjust which qubits interact with each other and create entanglement, the shared state between particles over time and space.
That flexibility could help overcome two of the biggest obstacles facing practical quantum systems:
- Scaling machines to large numbers of qubits
- Correcting the errors that inevitably creep into quantum calculations
The Room-Temperature Advantage
The key advantage is temperature. Most quantum computers need elaborate cooling systems to keep their superconducting circuits at near absolute zero. Shunkai operates at room temperature, which removes a major engineering hurdle.
That makes the system easier to use. Project lead Kenji Ohmori, a professor of photo-molecular science at the Institute for Molecular Science, said in a statement that researchers’ use of Shunkai would “lead to ripple effects on various fields in industry, academia, and government around the world.”
The team plans to integrate Shunkai into an existing shared supercomputing facility to create a quantum-GPU hybrid computing center. Opening it to external users over the coming years is part of the plan.
Scaling Up
Shunkai starts small. It will initially operate with around 50 qubits before expanding to roughly 500. The longer-term goal is considerably more ambitious: by March 2031, the team aims to scale Shunkai into a “large-scale, high-performance neutral-atom fault-tolerant quantum computer, with 10,000 physical qubits and quantum error detection and correction capabilities.”
Doing so would place it comfortably above the 6,100-qubit, neutral atom array demonstrated by Caltech researchers in October 2025.
Why Neutral Atoms Matter
Neutral atom-based quantum computers have recently been rapidly attracting attention around the world as a new modality that could exceed the limits of the superconducting modality, Ohmori 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.”
The comparison between the two approaches is worth pausing over. Superconducting circuits are the dominant model today, but they require extreme cooling. Neutral atoms avoid that cost by operating at room temperature, though they trade some speed for that stability.
| Modality | Cooling required | Error correction | Qubit count today |
|---|---|---|---|
| Superconducting circuits | Near absolute zero | Required | Leading systems run hundreds of qubits |
| Neutral atoms | Room temperature | Required | Caltech demonstrated 6,100 qubits in October 2025 |
Shunkai represents a bet on the future. The neutral atom path has been gaining attention globally, and Japan’s entry into the field signals that the country sees this as the direction the technology is headed.
What Comes Next
The team plans to partially open Shunkai to external researchers to develop applications and test and improve the system’s quantum error correction capabilities, representatives from Japan’s National Institutes of Natural Sciences said in the statement.
Each step along the way will test the system’s reliability and scalability. The team will need to demonstrate that Shunkai can handle the demands of real-world applications before it reaches its full potential.
The Ripple Effect
Ohmori’s statement points to broader impact. He described researchers’ use of Shunkai leading to ripple effects on various fields in industry, academia, and government around the world.
That ambition is not empty talk. Quantum computing is a foundational technology, and improvements in the field could reshape everything from cryptography to materials science to optimization problems that stump classical computers today.
The next few years will tell whether Shunkai lives up to its promise. For now, the switch-on is a milestone for Japan and for the broader field.
The machine is the first full-stack quantum computer of its kind in the country, meaning it features the software, control and hardware layers needed to read user inputs and return a result — not unlike a conventional PC. That integration is precisely what makes Shunkai notable. It is a working system with a clear path to production use.
The room-temperature design is the star of the show. By avoiding supercooling, Shunkai sidesteps one of the biggest barriers to quantum adoption. A machine that runs at room temperature is easier to deploy, easier to maintain, and easier to connect to existing infrastructure.
The neutral atom approach also offers flexibility in how qubits are arranged and connected. Researchers can adjust which qubits interact with each other during a calculation, creating entanglement between different pairs as needed. That adaptability is a powerful tool for building larger, more complex systems.
Shunkai’s journey from 50 qubits to 10,000 qubits will be measured in years, not months. The team’s stated timeline calls for the 10,000-qubit system to be ready by March 2031. That is a long horizon, but it is a realistic one given the steady progress the field has shown.
The Caltech array demonstrated in October 2025 reached 6,100 qubits using a similar neutral atom design. Shunkai will start at 50 qubits and expand to 500 before reaching its final target. Each step along the way will test the system’s reliability and scalability.
External researchers will play a key role in that process. By opening the machine to outside users, the team can draw on a wider pool of expertise to develop applications and improve the error correction capabilities. That collaborative approach increases the chances of success.
The field of quantum computing has been waiting for a practical system to emerge from the lab. Shunkai is a step in that direction. It operates at room temperature, uses a proven qubit design, and has a clear path to scale. Those three factors together make it a promising candidate for the future of the field.
The comparison to superconducting circuits is instructive. Superconducting systems are the dominant model today, but their reliance on extreme cooling has limited where they can be deployed. Neutral atom systems like Shunkai offer a different trade-off: they avoid the cooling costs that have made most quantum systems impractical outside finely tuned lab environments.
That balance could be decisive. A quantum computer that works reliably in a standard data center is more valuable than a faster machine that requires a cryogenic chamber. Shunkai’s design addresses the practical problem of deployment, which is why it has attracted attention globally.
The 10,000-qubit target is ambitious, but it is not without precedent. The Caltech array demonstrated 6,100 qubits in October 2025, and Shunkai’s design shares the neutral atom approach. The gap between 6,100 and 10,000 is substantial, but it is not unprecedented.
The team’s statement emphasizes the significance of Japan’s entry into the neutral atom modality. Ohmori said the development of Japan’s first full-stack quantum computer in this cutting-edge modality and its operation are extremely significant.
The ripple effect he described is real. Quantum computing touches almost every field of human endeavor, and a working system in Japan could accelerate research across industry, academia, and government. The external researcher program will be the mechanism through which that effect spreads.
Shunkai is a real machine, not a theoretical proposal. It has been switched on, and it is on the path to becoming a working system.
The road to 10,000 qubits will be bumpy. There will be technical challenges, funding questions, and unexpected setbacks. But the design is sound, the team is committed, and the technology is advancing steadily.
Japan’s first full-stack quantum computer is live. The country is now a player in this field, and Shunkai is the proof. The next few years will show whether the 10,000-qubit target holds.
Source material: “Japan switches on its first full-stack room-temperature quantum computer — and scientists plan to scale it up to 10,000 qubits,” Live Science.
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