Protecting quantum information through quantum error correction (QEC) is a cornerstone of future fault-tolerant quantum computation. However, current QEC-protected logical qubits have only achieved coherence times about twice those of their best physical constituents. Here, we show that the primary barrier to higher QEC gains is ancilla-induced operational errors rather than intrinsic cavity coherence. To overcome this bottleneck, we introduce error-detectable universal control of bosonic modes, wherein ancilla relaxation events are detected and the corresponding trajectories discarded, thereby suppressing operational errors on logical qubits. For binomial codes, we demonstrate universal gates with fidelities exceeding 99.6% and QEC gains of 8.33× beyond break-even. Our results establish that gains beyond 10× are achievable with state-of-the-art devices, establishing a path toward fault-tolerant bosonic quantum computing.
@article{arxiv.2601.21838,
title = {Error-detectable Universal Control for High-Gain Bosonic Quantum Error Correction},
author = {Weizhou Cai and Zi-Jie Chen and Ming Li and Qing-Xuan Jie and Xu-Bo Zou and Guang-Can Guo and Luyan Sun and Chang-Ling Zou},
journal= {arXiv preprint arXiv:2601.21838},
year = {2026}
}