Rigetti makes 36-qubit multi-chip Cepheus-1-36Q generally available, halving two-qubit error vs Ankaa-3
On 2025-08-12, alongside its Q2 results, Rigetti Computing announced general availability of Cepheus-1-36Q, a 36-qubit superconducting quantum computer built from four chiplets, on its Quantum Cloud Services platform, with Microsoft Azure availability to follow. Rigetti reported a 2x reduction in median two-qubit gate error rate versus its 84-qubit Ankaa-3 system and a median two-qubit gate fidelity of 99.5%, describing it as the first multi-chip quantum computer at this performance level and the system with the most chiplets to date. Disclosed under Form 8-K Item 7.01 and GlobeNewswire; HPCwire carried it.
Bringing a four-chiplet, multi-chip 36-qubit system to general availability with a stated 2x two-qubit-gate-error reduction is a concrete demonstration of Rigetti's modular-scaling thesis, resting on a named, verifiable fidelity metric (99.5% median two-qubit) rather than a marketing claim; per section 8 a product GA carrying a named benchmark improvement clears the material bar.
If the chiplet/multi-chip approach scales qubit count while holding two-qubit fidelity, it attacks the fabrication-yield ceiling that constrains monolithic superconducting processors and gives Rigetti a differentiated scaling story; the open question is whether inter-chip coupling preserves fidelity beyond four chiplets.