RIKEN IBM Quantum System Two

RIKEN IBM Quantum System Two is a superconducting circuits quantum computer operated by RIKEN in Japan. It has 156 physical qubits. It ranks 7 of 43 superconducting machines in this table by physical qubit count. 12 sourced specs are in the spec sheet. 4 published benchmark or milestone records are listed below, each marked by who measured it.

Also known as IBM Quantum System Two at R-CCS Kobe

First IBM Quantum System Two installed outside the United States, launched 24 June 2025 at the RIKEN Center for Computational Science in Kobe. IBM says it is co-located with Fugaku and linked to it by a high-speed network at the instruction level for quantum-centric supercomputing work. RIKEN confirms the 156-qubit Heron system is installed at R-CCS and held a ceremony for the combined operation. Error and speed figures are IBM's.

Co-located supercomputer: Fugaku. This machine is integrated with, or hosted beside, that system.

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	IBM Quantum Heron, 156 qubits	Vendor reported	Both IBM and RIKEN R-CCS describe a 156-qubit Heron processor; neither states the Heron revision (r2 or r3).	newsroom.ibm.com r-ccs.riken.jp
Qubit type	fixed-frequency transmon qubits with tunable couplers	Vendor reported	IBM describes Heron as fixed-frequency qubits with tunable couplers and a 2025 preprint on Heron r2 calls them transmon; family-level, the Heron revision at RIKEN is not stated.	ibm.com arxiv.org
Topology	heavy-hex lattice, 156 qubits	Vendor reported	IBM documentation gives Heron r2 as 156 qubits in a heavy-hexagonal lattice; family-level, the Heron revision at RIKEN is not stated.	quantum.cloud.ibm.com arxiv.org
Max connectivity	3	Independent	A 2025 paper on ibm_marrakesh says heavy-hex sites have coordination numbers two and three, so a qubit couples to at most three others; family-level.	arxiv.org
Native gates	CZ, RZ, SX, X, ID	Vendor reported	IBM documentation lists these supported gates on a Heron r2 backend and a 2024 survey lists the same basis gates for Heron r2; family-level, not read from this unit.	quantum.cloud.ibm.com arxiv.org
Single-qubit gate time	36 ns	Independent	Median single-qubit gate length on the Heron r2 backend ibm_marrakesh in a 2026 paper; family-level, not measured on this unit.	arxiv.org
Two-qubit gate time	68 ns	Independent	Median CZ duration on Heron r2 backends ibm_marrakesh (2026 paper) and ibm_fez (2024 survey); family-level, the Heron revision at RIKEN is not stated.	arxiv.org arxiv.org
Cooling and environment	dilution refrigerator (Bluefors KIDE platform in the System Two cryostat)	Vendor reported	IBM's 2022 blog says System Two would first use Bluefors' Kide platform and a Bluefors-focused Quantum Insider post (Jan 2024) says Kide sits at the heart of System Two; IBM-wide, not a unit-specific statement.	ibm.com thequantuminsider.com
Operating temperature	10 mK	Vendor reported	IBM says the qubits sit about a hundredth of a degree above absolute zero and Bluefors lists a typical Kide base temperature of 10 mK; platform-level, not measured on this unit.	ibm.com bluefors.com
Software	Qiskit SDK, Qiskit Runtime	Vendor reported	IBM's stack for its quantum systems; the 2023 System Two launch release names Qiskit Runtime and Qiskit 1.0, and IBM documentation uses qiskit-ibm-runtime.	newsroom.ibm.com quantum.cloud.ibm.com
Access and pricing	on-premises at RIKEN R-CCS in Kobe, co-located with and linked to Fugaku	Vendor reported	IBM says the system is linked to Fugaku at the instruction level; RIKEN says it is installed at R-CCS; neither states user access terms or a price.	newsroom.ibm.com r-ccs.riken.jp
Roadmap	IBM plans Starling, a fault-tolerant system with 200 logical qubits and 100 million gates, for 2029	Vendor reported	IBM's hardware page (read 2026-10-09) states this for the System Two line; it is not specific to the RIKEN unit.	ibm.com ibm.com

Published benchmark figures

These are numbers the builder or a paper reports for this machine, not results from a common test. The basis column says who measured them. What the metrics mean and why they are not comparable across technologies.

Metric	Value	Measured	Basis	Note	Source
Circuit layer operations per second (CLOPS)	250,000	2025-06-24	Vendor reported	IBM-stated CLOPS for Heron, described as 10x better than Eagle	newsroom.ibm.com
Error per layered gate (EPLG)	0.3%	2025-06-24	Vendor reported	Two-qubit error across a 100-qubit layered circuit, 3x10^-3, as stated by IBM for the 156-qubit Heron	newsroom.ibm.com
Two-qubit gate fidelity	99.9%	2025-06-24	Vendor reported	From best two-qubit error of 1x10^-3 stated by IBM; best coupler, not a median	newsroom.ibm.com

Milestone claims

IBM, RIKEN, Cleveland Clinic: protein complexes up to 12,635 atoms simulated on 156-qubit Heron systems at RIKEN and Cleveland Clinic with two supercomputers; preprint (2026-05-05, vendor reported) newsroom.ibm.com riken.jp

Timeline

2025-06-24: First operational
2026-10-04: 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 Heron	IBM	156	operational
IBM-Euskadi Quantum System Two	IBM-Euskadi Quantum Computational Center	156	operational
IBM Quantum System Two (Chicago)	IBM	156	under construction
LUMI-IQ	CSC	150	planned
Origin Wukong-180	Origin Quantum	180	operational
IBM Eagle	IBM	127	decommissioned