Extremely Low-Cost Magic State Preparation toward Fault-Tolerant Quantum Computing

• URL: http://arxiv.org/abs/2609.12698v1
• Date: Fri, 11 Sep 2026 10:45:47 GMT
• Title: Extremely Low-Cost Magic State Preparation toward Fault-Tolerant Quantum Computing
• Abstract summary: Fault-tolerant preparation of non-Clifford resource states is a major contributor to the overhead of quantum computation.<n>We introduce a low-cost magic-state preparation protocol in which the choice of stabilizer generators is co-designed with a flag gate.
• Score: 5.4190091415164
• License: http://arxiv.org/licenses/nonexclusive-distrib/1.0/
• Abstract: Fault-tolerant preparation of non-Clifford resource states is a major contributor to the overhead of quantum computation, motivating protocols that achieve high output fidelity with minimal qubit and circuit costs. We introduce a low-cost magic-state preparation protocol in which the choice of stabilizer generators is co-designed with the flag gadgets, allowing the syndrome-extraction circuit itself to filter correlated faults across a non-Clifford layer. The protocol prepares a logical plus state in the 15-qubit quantum Reed-Muller code, applies a transversal T gate, and gauge-fixes the same register into the seven-qubit Steane code. By reorganizing equivalent Z-type stabilizer generators into jointly flagged measurement groups, the protocol eliminates all accepted logical-error contributions arising from one or two circuit faults under destructive error detection. Under a uniform circuit-level depolarizing noise model, the postselected infidelity is $210.2p^3+O(p^4)$. At $p=10^{-3}$, exact low-order enumeration combined with stratified sampling bounds the infidelity by $2.2\times10^{-7}$ at 99.9% joint confidence, while retaining an acceptance probability of 86.9%. The complete circuit requires only 19 qubits and 82 CNOT gates. These results demonstrate that stabilizer-generator design can substantially reduce the cost of postselected magic-state preparation, although corrected operation and the fidelity of an unmeasured output block require separate analysis.

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