Rigetti Computing has delayed the launch of its 108-qubit Cepheus-1-108Q quantum system, now expecting general availability around the end of Q1 2026. The company encountered technical challenges with tunable couplers, requiring another chip iteration to meet its performance standards. Cepheus-1-108Q is the industry’s largest modular quantum computer.
“While we are making strong progress with Cepheus-1-108Q, we are taking more time to test and optimize the system to ensure the performance is up to our standards.”
— Dr. Subodh Kulkarni, CEO, Rigetti Computing
Cepheus-1-108Q System Roadmap & Availability
The delay allows for further testing and optimization aimed at achieving 99.5% median two-qubit gate fidelity, up from the current 99%. Challenges encountered with tunable couplers prompted another chip iteration to enhance the system and improve overall fidelity metrics. The 108-qubit system is constructed from twelve 9-qubit chiplets utilizing Rigetti’s modular architecture, making it the largest of its kind in the industry. Current performance data shows a median two-qubit gate fidelity of 99% on the 108-qubit system, alongside 99.7% and 99.6% fidelity on their 9- and 36-qubit systems, respectively. Rigetti’s in-house fabrication at Fab-1 supports this development of scalable, multi-chip quantum processors.
Rigetti’s 99%+ Fidelity Across Multiple Qubit Systems
Rigetti is demonstrating high fidelity across its quantum computing systems, with its 108-qubit processor achieving 99% median two-qubit gate fidelity. Notably, smaller systems also show strong performance—the 9-qubit processor reached 99.7% fidelity and the 36-qubit system measured 99.6%. This consistency across different qubit counts highlights Rigetti’s progress in building reliable quantum processors, vital for complex calculations. The company’s modular architecture, utilizing 9-qubit chiplets, supports these fidelity levels and enables scalable systems like the 108-qubit Cepheus-1-108Q. Rigetti deployed an earlier multi-chip system, Cepheus-1-36Q, in 2025, demonstrating its experience with this technology. These advancements are driven by in-house fabrication at Fab-1, allowing for dedicated optimization of device manufacturing and improved system performance.
Superconducting Qubits & Modular Chip Architecture
Rigetti’s 108-qubit system, Cepheus-1-108Q, utilizes a modular architecture constructed from twelve 9-qubit chiplets. This approach represents an industry first, demonstrating a scalable path for building larger quantum processors by tiling multiple smaller chips together—a method proven with the prior 36-qubit Cepheus-1 system. The modular design allows Rigetti to leverage its proprietary technology for creating multi-chip quantum processors, addressing the challenges of increasing qubit counts. Superconducting qubits underpin Rigetti’s systems, a technology favored for its maturity, potential for scalability, and fast operation—achieving gate speeds of 50-70ns. This speed is significantly faster, around 1,000 times, compared to alternative qubit modalities like ion traps and neutral atoms. Rigetti further supports scalability through in-house chip fabrication at Fab-1, a dedicated facility for quantum device manufacturing.
