AI 中文总结
本文提出一种软束搜索解码器，利用内部数据作为置信度指标，在量子LDPC码上实现高达580倍逻辑错误抑制，并显著延长逻辑量子比特寿命，使所有测试码型超越盈亏平衡点。
AI 中文摘要
解码器是容错量子计算机的关键组件，它根据整个计算过程中执行的奇偶校验测量来计算校正。软解码器在其输出中附加一个置信度分数，当与后选择结合使用时，可以显著提高逻辑性能。我们提出了一种用于量子低密度奇偶校验码的软束搜索解码器，该解码器使用内部解码器数据作为置信度度量，从而无需额外计算。我们对五个与超导和俘获离子架构相关的量子LDPC码进行了电路级模拟，配备了我们的全局软解码器，在物理错误率为$10^{-3}$时，我们获得了高达$580\ imes$的逻辑错误抑制，同时仅拒绝了$0.1\%$的射击。然后，我们使用软束解码器的流式版本模拟了一个错误检测测量，这是行走猫架构的核心逻辑操作，我们实现了高达$210\ imes$的错误抑制，同时拒绝概率仅增加了$0.5$个百分点。最后，我们重新审视了最近在俘获离子上进行的量子LDPC码记忆实验，证明我们的软解码器将逻辑量子比特寿命延长了一倍，代价是每个综合征轮的平均拒绝率为$2.6\%$--$5.6\%$，使所有五种码都进入了超越盈亏平衡点的状态。
英文摘要
The decoder is a critical component of a fault-tolerant quantum computer, computing corrections based on parity-check measurements performed throughout the computation. A soft decoder supplements its output with a confidence score which, when used alongside post-selection, can substantially improve logical performance. We introduce a soft beam search decoder for quantum low-density parity-check codes that uses internal decoder data as a confidence metric, removing the need for extra computation. We perform circuit-level simulations of five quantum LDPC codes relevant for superconducting and trapped ion architectures equipped with our global soft decoder and we obtain up to $580\times$ logical-error suppression at a physical error rate of $10^{-3}$ while rejecting only $0.1\%$ of shots. Then, we simulate an error detected measurement, which is a core logical operation of the walking cat architecture, using a streaming version of soft beam decoder and we achieve up to $210\times$ error suppression while increasing the rejection probability by only $0.5$ percentage points. Finally, we revisit recent quantum LDPC code memory experiments on trapped ions, demonstrating that our soft decoder doubles the logical qubit lifetimes at the price of a mean rejection rate of $2.6\%$--$5.6\%$ per syndrome round, bringing all five codes into the beyond-breakeven regime.
