RGTI's 108-Qubit Performance Hurdle Highlights Scaling Challenge Ahead

Rigetti Computing’s RGTI stated in its latest technology update that the biggest challenge in its quantum roadmap is no longer adding more qubits but improving the performance of its flagship 108-qubit Cepheus system. During the second quarter of 2026 earnings call, management acknowledged that coherence time has become the primary bottleneck limiting two-qubit gate fidelity, even as Cepheus-1-108Q stands among only three generally available gate-based quantum computers with more than 100 qubits. The system currently operates with coherence times of roughly 25-30 microseconds, a level that constrains the reliability of quantum operations and underscores why scaling qubit counts alone is insufficient to unlock practical commercial workloads.

Rigetti is now directing significant engineering efforts toward overcoming this limitation through chip redesigns, fabrication process improvements and the adoption of new materials, including tantalum-capped superconducting contacts aimed at reducing performance degradation. Management expects these initiatives to gradually double or even triple coherence times over the next several years, paving the way for stronger two-qubit gate performance and more dependable quantum computations.