University of Tokyo IBM Quantum System One

University of Tokyo IBM Quantum System One is a superconducting circuits quantum computer operated by University of Tokyo in Japan. It has 127 physical qubits. It ranks 12 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 UTokyo QII IBM Quantum System One

Japan's first IBM Quantum System One, managed by the University of Tokyo for the Quantum Innovation Initiative Consortium. It started with a 27-qubit Falcon, was upgraded to a 127-qubit Eagle in 2023 (completion announced 27 November 2023), and in May 2025 UTokyo and IBM announced a further upgrade to a 156-qubit Heron expected later in 2025 plus a link to the Miyabi supercomputer. Completion of that upgrade was not confirmed in the pages consulted, so the Eagle figure is recorded.

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	127-qubit Eagle r3 in 2024; upgrade to 156-qubit Heron announced May 2025, completion not confirmed	Vendor reported	A July 2024 survey (arXiv 2410.00916) lists backend ibm_kawasaki, which the UTokyo poster names as this System One, as Eagle r3; IBM announced the Heron upgrade for later in 2025.	newsroom.ibm.com itc.u-tokyo.ac.jp
Qubit type	fixed-frequency transmon qubits	Peer reviewed	A Nature paper describes the 127-qubit Eagle ibm_kyiv as fixed-frequency transmons and a 2024 survey says IBM processors are transmon-based; family-level; it also holds for Heron r2 apart from the qubit count.	pmc.ncbi.nlm.nih.gov arxiv.org
Topology	heavy-hex lattice	Peer reviewed	The Nature paper gives heavy-hex connectivity for Eagle and the 2024 survey says Eagle uses a heavy-hexagonal layout; family-level; it also holds for Heron r2 apart from the qubit count.	pmc.ncbi.nlm.nih.gov arxiv.org
Cooling and environment	dilution refrigerator inside the System One enclosure	Vendor reported	IBM's blog says its quantum processors sit in a dilution refrigerator that reaches 15 to 20 millikelvin; this is an IBM-wide statement, not specific to this unit.	ibm.com
Access and pricing	on-premises, administered by UTokyo, for Quantum Innovation Initiative Consortium members	Vendor reported	IBM's 2023 release describes exclusive use by QII members and the 2025 announcement says UTokyo administers it for QII members; no price is published.	newsroom.ibm.com u-tokyo.ac.jp
Predecessor	27-qubit Falcon configuration of the same System One, replaced by Eagle in 2023	Vendor reported	IBM's May 2025 release and the UTokyo Japanese-language announcement both say it started with a 27-qubit Falcon and moved to a 127-qubit Eagle in 2023.	newsroom.ibm.com u-tokyo.ac.jp
Successor	156-qubit IBM Heron processor in the same System One, announced 15 May 2025 for later that year	Vendor reported	Plan announced by UTokyo and IBM; completion of the upgrade was not confirmed in the pages consulted.	newsroom.ibm.com u-tokyo.ac.jp
Roadmap	link to the Miyabi supercomputer, with a hybrid service starting in January 2026	Vendor reported	UTokyo's poster (January 2026) gives the Miyabi hybrid service start, after IBM and UTokyo announced the link on 15 May 2025.	itc.u-tokyo.ac.jp newsroom.ibm.com

Timeline

2023-11-27: First operational
2025-05-18: Status checked: operational

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
IBM Eagle	IBM	127	decommissioned
Cleveland Clinic IBM Quantum System One	Cleveland Clinic	127	operational
RPI IBM Quantum System One	Rensselaer Polytechnic Institute	127	operational
Yonsei IBM Quantum System One	Yonsei University	127	operational
IBM Nighthawk	IBM	120	operational
Rigetti Cepheus-1-108Q	Rigetti Computing	108	operational