Universal fault-tolerant quantum computers need non-Clifford gates, which typically require preparing high-quality magic states through costly distillation. Magic state cultivation is a proposed alternative that aims to improve a noisy magic state through quantum error correction, potentially reducing the hardware and time demands of producing these essential resources. Testing it requires more than storing quantum information: the process must be integrated with error-correcting codes, and the resulting state’s quality must be assessed reliably.
This experiment demonstrates cultivation on a superconducting quantum processor, including a transition, or code-switch, into a surface code. The team also developed a fault-tolerant measurement procedure to place a bound on the cultivated state’s fidelity. Cultivation reduced errors by a factor of 40, yielding a state fidelity of 0.9999(1); this result came from 8% of attempts, reflecting the proportion retained by the protocol. The findings show that cultivation can produce exceptionally accurate magic states on real hardware and support its potential as a practical alternative to resource-intensive distillation. The work addresses a key obstacle to scalable quantum computing: generating the non-Clifford resources needed for universal computation while limiting the overhead imposed by error correction.
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