论文标题
易于故障测量的无量子误差校正多数门
Fault-tolerant measurement-free quantum error correction with multi-qubit gates
论文作者
论文摘要
无测量的量子误差校正(MFQEC)在具有无条件量子置换栅极的平台中提供了基于标准测量的QEC的替代方案。我们重新审查了利用多量门门和冗余综合征提取的Steane代码的无测量变体的容错问题(FT)的问题,从而发现了以前被忽略的相互作用误差,破坏了FT。然后,我们构建了一个对所有单量错误具有抵抗力的修订的MFQEC电路,但仍无法忍受某些相关误差。为了系统地调查FT,我们引入了一种有效的方法,以(i)Clifford Gates用于综合征提取的MFQEC电路,(II)综合征控制的Pauli操作用于解码,(III)Pauli噪声模型。因此,我们在文献中先前考虑的有限噪声模型下,为我们修订的MFQEC Steane代码找到了$ \ sim0.7 \%$的假设。然后,我们放松噪声模型的假设,以确定具有多数门的FT的一般要求,发现现有的多Qubit中性原子门与耐故障综合征的提取是不兼容的,可以直接实现基于测量的Steane代码的无测量和无测量的变体。将多Qubit大门分解为两倍的大门,类似地破坏了ft。最后,我们讨论了为MFQEC代码恢复FT所必需的理论成分,包括单发ft和Heußen\ textit {et al。}〜[arxiv:2307.13296]的最新提案,以通过````''[arxiv:2307.13296]来通过````'''''''''''''''''''通过组合多量门门,冗余综合征提取和复制辅助ft,我们构建了steane代码的无测和耐故障变体和$ \ sim0.1 \%$ $ $ $ $ $的伪舍库。
Measurement-free quantum error correction (MFQEC) offers an alternative to standard measurement-based QEC in platforms with an unconditional qubit reset gate. We revisit the question of fault tolerance (FT) for a measurement-free variant of the Steane code that leverages multi-qubit gates and redundant syndrome extraction, finding previously overlooked phase-flip errors that undermine FT. We then construct a revised MFQEC circuit that is resistant to all single-qubit errors, but which nonetheless cannot tolerate certain correlated errors. In order to investigate FT systematically, we introduce an efficient method to classically simulate MFQEC circuits with (i) Clifford gates for syndrome extraction, (ii) syndrome-controlled Pauli operations for decoding, and (iii) a Pauli noise model. We thereby find a pseudothreshold of $\sim0.7\%$ for our revised MFQEC Steane code under a restricted noise model previously considered in the literature. We then relax noise model assumptions to identify general requirements for FT with multi-qubit gates, finding that existing multi-qubit neutral atom gates are incompatible with fault-tolerant syndrome extraction in a straightforward implementation of both measurement-based and measurement-free variants of the Steane code. Decomposing multi-qubit gates into two-qubit gates similarly spoils FT. Finally, we discuss the theoretical ingredients that are necessary to recover FT for MFQEC codes, including single-shot FT and a recent proposal by Heußen \textit{et al.}~[arXiv:2307.13296] to achieve FT by ``copying'' errors onto an ancilla register. By combining multi-qubit gates, redundant syndrome extraction, and copy-assisted FT, we construct a measurement-free and fault-tolerant variant of the Steane code with a pseudothreshold of $\sim0.1\%$.