IBM’s approach is to use quantum processors as co-processors, not replacements for classical computers. In this Q&A, IBM Spain’s director of quantum computing, Mikel Díez, explains how the two kinds of machines can divide work, what IBM’s San Sebastián installation adds, and why current noisy processors are not the same as fault-tolerant quantum computers.
What does hybrid quantum-classical computing mean?
It means using a quantum processor and classical computers in the same workflow, assigning each the tasks it is suited to handle. Classical machines remain responsible for conventional computation, data handling and coordinating the process. A quantum processor is used for selected subproblems where its operations may be useful.
“At IBM, we don’t see quantum computing working alone, but rather alongside classical computing so that each does what it does best,” says Mikel Díez, IBM’s director of quantum computing in Spain.
This is a division of labor, not a plan to replace ordinary computers. The classical system does not disappear when a quantum processor is added, and using a quantum computer does not automatically make an entire application faster or better.
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How does IBM’s quantum computer work with a classical computer?
In Díez’s materials-simulation example, researchers decide which parts of a problem should run on classical computers and which should run on a quantum processor. They then combine the outputs. The useful unit is the overall workflow: a quantum calculation can contribute a result without taking over data preparation, orchestration or the rest of the computation.
- Prepare the problem classically. Researchers organize the data and identify a subproblem that may suit quantum processing.
- Run the selected computation on a quantum processor. The processor executes the quantum circuit for that part of the task.
- Use classical computing to interpret and continue. Classical systems manage the surrounding computation and combine the quantum result with the rest of the workflow.
Díez also points to AI pattern-finding: classical processing handles a large body of data, while quantum processing could contribute to selected work that classical methods do not reach. This is an example of a potential division of labor, not evidence that today’s quantum processors outperform classical AI systems on general tasks.
What is IBM Quantum System Two in San Sebastián?
IBM and the Basque Government inaugurated the IBM-Euskadi Quantum Computational Center in San Sebastián on October 14, 2025. IBM describes the installation as Europe’s first IBM Quantum System Two and says it is the company’s second System Two deployment outside the United States. The system is powered by a 156-qubit IBM Quantum Heron processor.
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The center is on the Ikerbasque Foundation campus and forms part of BasQ, the Basque quantum initiative. The IBM–Basque Government partnership behind it began in 2023. IBM says BasQ members receive access to one of its most powerful systems and that the partnership is intended to support collaborations in fundamental physics and materials science.
Why put quantum and classical equipment in the same place?
Díez says colocation can reduce latency when a process needs frequent interaction between quantum and classical systems. A local installation also gives the host control over access and can help attract talent and build a regional ecosystem. He notes a trade-off: a third-party facility may require the operator to meet demanding quality standards.
IBM presents BasQ as more than a machine installation: it aims to develop quantum science, skills, investment and applications across energy, industry, biomedicine and AI. Those are areas of interest for the ecosystem, not a list of applications already shown to deliver practical results on this system.
Is IBM’s quantum computer useful yet?
IBM’s current machines are physical systems that researchers can access, but Díez says the San Sebastián computer is noisy, which limits some features. Noise means operations can produce errors, so present-day research use should not be confused with fault-tolerant computing: a more advanced state in which error-correction techniques allow reliable computation at larger scale.
IBM announced in March 2025 that its 156-qubit Heron system can use Qiskit to run certain classes of circuits with up to 5,000 two-qubit gate operations. IBM described those workloads as beyond brute-force classical simulation. That is IBM’s stated capability for particular circuit classes, not an independent benchmark or proof that the system is broadly more useful than classical computers.
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IBM identifies materials simulation and selected AI workloads as examples of hybrid research, and names areas such as drugs, energy grids and finance among potential application domains. Those ambitions should be distinguished from demonstrated advantage: the interview does not establish that the San Sebastián system has already solved practical problems in those sectors better than classical methods.
What can quantum computers do that classical computers cannot?
There is no blanket answer that applies to every task. Quantum computers process information using quantum states and operations, which may offer an advantage for particular problems. Whether that advantage is real and useful depends on the problem, the quality and scale of the hardware, and the cost of the full workflow, including classical processing and error handling.
For now, IBM’s framing is selective: use quantum processors to explore hard subproblems inside hybrid workloads, rather than assume they can replace classical computing or accelerate ordinary software. Claims about a workload being beyond brute-force simulation also do not establish superiority across other workloads.
Independent reader supportYour contribution helps us test, update, and keep practical guides available for everyone.When does IBM expect fault-tolerant quantum computing?
Díez describes the following milestones as IBM roadmap expectations. They are targets, not completed achievements:
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| Target year | IBM roadmap expectation |
|---|---|
| 2026 | Discover quantum advantage in selected hybrid workloads. |
| 2029 | Offer a commercially available fault-tolerant machine with 200 logical qubits. |
| 2033 | Reach 2,000 logical qubits. |
Physical qubits are hardware components; logical qubits are encoded units intended to support computation with error correction. The roadmap figures therefore describe future logical-qubit goals, not the number of physical qubits in the San Sebastián processor. Actual delivery and performance remain subject to IBM meeting its targets.
How large is IBM’s quantum program?
In a 2025 interview, IBM reported building more than 60 quantum computers since 2019; operating approximately 10 quantum computers remotely from cloud locations in the United States and Europe; providing access to more than 500,000 developers; and executing more than 3 trillion quantum circuits. These are company-reported scale figures, not independently audited measurements of application performance.
How can you try IBM Quantum or Qiskit?
IBM Quantum Platform and Qiskit are the starting points for exploring IBM’s quantum-computing tools. Qiskit is IBM’s software framework for working with quantum circuits; the platform provides a route to IBM quantum resources. Availability and access conditions can vary, so check IBM’s current platform information before planning work that depends on a particular processor. A useful first exercise is to run a small circuit, inspect its results, and compare what changes when noise is considered; a small demonstration circuit should not be taken as evidence of advantage on a real-world problem.
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