Quantum/Machines/Rigetti Cepheus-1-36Q
USA · operational · Superconducting circuits
Rigetti Cepheus-1-36Q
Rigetti Cepheus-1-36Q is a superconducting circuits quantum computer operated by Rigetti Computing in USA. It has 36 physical qubits. It ranks 35 of 53 superconducting machines in this table by physical qubit count. 6 sourced specs are in the spec sheet. 1 published benchmark or milestone record are listed below, each marked by who measured it.
Also known as 36-qubit multi-chip system
Rigetti's first multi-chip system, announced in mid-August 2025 with four chips and a stated 99.5 percent median two-qubit fidelity, a 2x reduction in error rate versus Ankaa-3. The date is taken from a news repost; the Rigetti page itself shows a different date line. As fetched on 2026-10-13, Amazon Braket's device page lists only Rigetti Ankaa-3 and Cepheus-1-108Q, and Microsoft's Azure Quantum Rigetti page (updated April 2026) lists only Cepheus-1-108Q; neither lists Cepheus-1-36Q, so current public cloud availability is not confirmed. Status is left unchanged because no source says the system was retired.
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 | Cepheus-1-36Q: four 9-qubit chiplets in one modular multi-chip system | Vendor reported | August 2025 reports describe four separate chips tiled together; the April 2026 release says the 108-qubit system triples the chiplet count of this one. | finance.yahoo.comthequantuminsider.com |
| Cloud platforms | Rigetti Quantum Cloud Services | Vendor reported | At the August 2025 announcement Microsoft Azure was listed as coming soon, but the Azure Quantum Rigetti page and the Braket device list now show only other Rigetti systems. | finance.yahoo.com |
| Access and pricing | Cloud access through Rigetti Quantum Cloud Services | Vendor reported | No published price found; current availability is not confirmed by the sources used. | finance.yahoo.com |
| Predecessor | Rigetti Ankaa-3 | Vendor reported | Rigetti states a 2x reduction in two-qubit gate error versus Ankaa-3, which the report calls its predecessor. | finance.yahoo.com |
| Successor | Rigetti Cepheus-1-108Q | Vendor reported | The April 2026 release says the 108-qubit system triples the qubits and chiplets of Cepheus-1-36Q. | thequantuminsider.comquantumcomputingreport.com |
| Roadmap | Targeted a 100+ qubit system with similar fidelity by end of 2025 | Vendor reported | Stated in August 2025; the 108-qubit system became generally available in April 2026 at 99.1 percent median two-qubit fidelity. | finance.yahoo.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 |
|---|---|---|---|---|---|
| Two-qubit gate fidelity | 99.5% | 2025-08 | Vendor reported | Median two-qubit gate fidelity, four-chip 36-qubit system; Rigetti states a 2x error reduction versus Ankaa-3 | rigetti.comfinance.yahoo.com |
Timeline
- 2025-08: Announced
- 2025-08: First operational
More from Rigetti Computing
- Rigetti Ankaa-3 (operational, 84 qubits)
- Rigetti Cepheus-1-108Q (operational, 108 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 |
|---|---|---|---|
| OQC Toshiko | Oxford Quantum Circuits | 32 | operational |
| Fraunhofer IBM Quantum System One | Fraunhofer-Gesellschaft | 27 | operational |
| VTT Q50 | VTT | 50 | operational |
| QpiAI-Indus | QpiAI | 25 | operational |
| Google Sycamore | Alphabet | 53 | operational |
| Euro-Q-Exa | LRZ | 54 | operational |