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 30 of 43 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. It is no longer in the Amazon Braket device list, and the sources used do not confirm whether it remains available.
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 |
| Google Sycamore | Alphabet | 53 | operational |
| Euro-Q-Exa | LRZ | 54 | operational |
| IQM Emerald | IQM Quantum Computers | 54 | operational |