发表机构
IBM Research; University of Chicago; Singapore University of Technology and Design; NVIDIA Corporation（IBM研究院; 芝加哥大学; 新加坡科技设计大学; 英伟达公司）
机构由 AI 辅助整理，请以论文原文为准。AI 中文总结
研究如何将基于采样方案的复杂性理论难度与量子计算所需能力结合，引入结构化电路解决问题，通过时空码编码抑制错误，用70量子比特、深度70的电路展示方案，有效降低错误率，产生一定保真度状态，是提升稳定器状态的系统方法。
AI 中文摘要
基于采样的方案是展示超越经典超级计算机能力的量子计算的重要候选方案。然而，将其复杂性理论上的难度与更广泛的可扩展量子计算所需的两种能力相结合一直很困难：抑制硬件错误和验证量子计算本身。在此，我们通过引入结构化电路来解决这两个问题，这种电路除了有可证明的难度保证外，还允许在量子码中进行编码。这使我们能够在高电路深度时同时达到高保真度，并通过电路结构和码综合征测量来认证实验保真度。所得证书依赖于设备，但比现有的保真度代理基准所需的噪声假设要弱得多。我们用一个掺杂了468个T门的70量子比特、深度为70的克利福德电路展示了我们的方案。我们总共使用97个物理量子比特在时空码中对该计算进行编码，在综合征后选择后有效地将门错误率降低了10倍，并以95%的置信度产生了一个保真度下限为0.284的状态。我们的构造是一种在保持错误检测保真度证书的同时将稳定器状态提升为魔法状态的系统方法。
英文摘要
Sampling-based proposals are prominent candidates for demonstrating quantum computations beyond the reach of classical supercomputers. However, it has been difficult to combine their complexity-theoretic hardness with two capabilities needed for scalable quantum computing more generally: suppressing hardware errors, and verifying the quantum computation itself. Here we address both issues by introducing structured circuits, which, in addition to provable hardness guarantees, admit an encoding in a quantum code. This allows us to simultaneously reach high fidelities at high circuit depths, and to certify an experimental fidelity via the circuit structure and measurement of code syndromes. The resulting certificate is device dependent, but requires substantially weaker noise assumptions than existing fidelity proxy benchmarks. We demonstrate our proposal with a $64$-qubit, depth-$73$ Clifford circuit, doped with $314$ $T$ gates. We use a total of $76$ physical qubits to encode this computation in spacetime codes, effectively suppressing gate error rates by $10\times$ after syndrome post-selection, and yielding a state with a fidelity lower bound of $0.349$ with $95\%$ confidence. Our construction is a systematic method for promoting a stabilizer state to a magic state while keeping an error-detected fidelity certificate.
