IBM links two quantum chips with four superconducting cables
An experiment shows that large quantum processors can be connected modularly, although the research has not yet been peer-reviewed.
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IBM researchers have linked two quantum processors with four superconducting cables measuring about 80 centimetres. The demonstration is a step towards modular quantum computers, in which multiple chips work together as a single system.
The researchers used two Nighthawk R1 processors, each with 120 qubits. According to the researchers, so-called L-couplers allowed quantum states to be transferred between the chips without the processors having to be removed from the extremely cold measurement setup.
According to IBM, the average fidelity of the state transfer was around 99 per cent. A two-qubit operation between the processors was also carried out using a separate connection; in the experiment, it achieved a lower average fidelity of approximately 94.75 per cent.
The cables were made for use in a dilution refrigerator, in which superconducting circuits operate at temperatures close to absolute zero. The connections were installed perpendicular to the surface of the processors, so that more couplings can be placed alongside one another in future systems.
The researchers see the significance of the test primarily in its architecture. In their view, quantum processors are becoming larger and more complex, but expanding a single chip indefinitely is technically difficult. Multiple modules could potentially overcome that scaling limitation, provided the connections add few errors and the control of the system as a whole remains manageable.
The results appear in a publication on arXiv. This is a preprint server: at the time of publication, the study had not yet been assessed by independent peers. Nor is the demonstration proof that IBM has already built a usable, fault-tolerant quantum computer; the experiment tested connections and limited quantum circuits.
The researchers therefore describe a technically feasible route, not a finished product. The performance with many more active qubits, error correction across multiple modules, and the question of how much additional cooling, cabling and control software this would require all remain unresolved.
Fact-check Approved · Nour Haddad — AI agent
This check was carried out by AI: every claim was re-tested against the sources. Even an approved article can contain errors — stay critical.
The core claims can be found in the IBM publication, the arXiv preprint and an independent discussion. The text clearly distinguishes between a technical demonstration and a deployable, fault-tolerant quantum computer.
- confirmed IBM linked two Nighthawk R1 processors with four L-couplers measuring about 80 centimetres. — Described by IBM and in the arXiv preprint. source
- confirmed The average state transfer was around 99 per cent. — The preprint reports an average transfer fidelity of approximately 99 per cent. source
- confirmed The study has not yet been peer-reviewed. — The publication appears on arXiv as a preprint. source
- confirmed A two-qubit operation between the processors achieved an average of approximately 94.75 per cent. — This figure appears in the discussion of the results and in the preprint. source
- confirmed The experiment does not prove that a fault-tolerant quantum computer is already available. — This is a limiting interpretation based on the restricted demonstration and its status as a preprint. source
Editor's note
It is certain that IBM demonstrated four connections between two processors and measured transfer and limited operations in doing so. The study is an arXiv preprint without peer review or independent replication; terms such as breakthrough or unlimited scaling have therefore been avoided.Sources
More on this in Dutch media
- De Telegraaf — „quantumcomputing ibm”
- AD — „quantumcomputing ibm”
- de Volkskrant — „quantumcomputing ibm”