Quantum/Machines/RIKEN Fujitsu 256-qubit
Japan · operational · Superconducting circuits
RIKEN Fujitsu 256-qubit
RIKEN Fujitsu 256-qubit is a superconducting circuits quantum computer operated by RIKEN in Japan. It has 256 physical qubits. It ranks 5 of 43 superconducting machines in this table by physical qubit count. 8 sourced specs are in the spec sheet. No benchmark figures are recorded for it yet.
Also known as 256-qubit superconducting quantum computer
Announced in April 2025 and located at the RIKEN RQC-FUJITSU Collaboration Center on the Wako campus, with a plan to offer it to companies and research institutions from fiscal 2025. The RIKEN page does not explicitly say it is in routine operation and gives no fidelity data. The same release names a 1,000-qubit machine for 2026, which is not counted because no launch was found. It is at Wako, not beside Fugaku in Kobe, so no HPC link is set.
Spec sheet
Technical details as the builder or a paper states them, each with its own source. A blank is a fact we could not source, not a zero. Fidelity and coherence figures are in the benchmark table below.
| Spec | Value | Basis | Note | Source |
|---|---|---|---|---|
| Processor | 256-qubit superconducting chip using the same 4-qubit unit cell as the 64-qubit machine | Vendor reported | Fujitsu and RIKEN announced it on 22 April 2025 at the RIKEN RQC-FUJITSU Collaboration Center. | info.archives.global.fujitsuriken.jp |
| Topology | 4-qubit unit cells arranged in a scalable 3D connection structure | Vendor reported | Unit cells are tiled in 3D to reach 256 qubits without a redesign; per-qubit connectivity is not stated. | info.archives.global.fujitsuthequantuminsider.com |
| Cooling and environment | Dilution refrigerator, same cooling unit as the 64-qubit system, with 4x implementation density | Vendor reported | The release stresses balancing control-circuit heat against refrigerator cooling capacity under ultra-high vacuum; no temperature is given. | info.archives.global.fujitsuriken.jp |
| Cloud platforms | Fujitsu and RIKEN platform for hybrid quantum computing | Vendor reported | The release does not use the word cloud; it says the machine joins the hybrid quantum computing platform offered globally. | info.archives.global.fujitsuthequantuminsider.com |
| Access and pricing | Offered to companies and research institutions worldwide from Q1 of fiscal 2025 | Vendor reported | This was a plan stated in April 2025; actual service start was not confirmed in the sources used. | info.archives.global.fujitsuriken.jp |
| Predecessor | RIKEN Fujitsu 64-qubit superconducting quantum computer (October 2023) | Vendor reported | Both say the 256-qubit machine builds on the 64-qubit system launched in October 2023. | info.archives.global.fujitsuriken.jp |
| Successor | Fujitsu 1,000-Qubit System | Vendor reported | Both state continued R&D toward a 1,000-qubit computer scheduled for 2026. | info.archives.global.fujitsuriken.jp |
| Roadmap | 1,000-qubit machine to be installed in a new building at Fujitsu Technology Park in 2026 | Vendor reported | Stated April 2025; the collaboration center agreement was also extended from March 2025 to March 2029. | info.archives.global.fujitsuthequantuminsider.com |
Timeline
- 2025-04: Announced
- 2025-04: First operational
More from RIKEN
- Reimei (operational, 20 qubits)
- RIKEN IBM Quantum System Two (operational, 156 qubits)
Comparable superconducting machines
Closest in physical qubit count within the same technology. Counts of different qubit types are not interchangeable across technologies.
| Machine | Operator | Qubits | Status |
|---|---|---|---|
| Origin Wukong-180 | Origin Quantum | 180 | operational |
| IBM Heron | IBM | 156 | operational |
| RIKEN IBM Quantum System Two | RIKEN | 156 | operational |
| IBM-Euskadi Quantum System Two | IBM-Euskadi Quantum Computational Center | 156 | operational |
| IBM Quantum System Two (Chicago) | IBM | 156 | under construction |
| IBM Osprey | IBM | 433 | decommissioned |