The overheads of classical decoding for quantum error correction grow rapidly with the number of logical qubits and their correction code distance. Decoding at room temperature is bottle-necked by refrigerator I/O bandwidth while cryogenic on-chip decoding is limited by area/power/thermal budget. To overcome these overheads, we are motivated by the observation that in the common case (over 90% of the time), error signatures are fairly trivial with high redundancy / sparsity, since the error correction codes are over-provisioned to be able to correct for uncommon worst-case complex scenarios (to ensure substantially low logical error rates). If suitably exploited, these trivial signatures can be decoded and corrected with insignificant overhead, thereby alleviating the bottlenecks described above, while still handling the worst-case complex signatures by state-of-the-art means. Our proposal, targeting Surface Codes, consists of: 1) A lightweight decoder for decoding and correcting trivial common-case errors, designed for the cryogenic domain. The decoder is implemented for SFQ logic. 2) A statistical confidence-based technique for off-chip decoding bandwidth allocation, to efficiently handle rare complex decodes which are not covered by the on-chip decoder. 3) A method for stalling circuit execution, for the worst-case scenarios in which the provisioned off-chip bandwidth is insufficient to complete all requested off-chip decodes. In all, our proposal enables 70-99+% off-chip bandwidth elimination across a range of logical and physical error rates, without significantly sacrificing the accuracy of state-of-the-art off-chip decoding. By doing so, it achieves 10-10000x bandwidth reduction over prior off-chip bandwidth reduction techniques. Furthermore, it achieves a 15-37x resource overhead reduction compared to prior on-chip-only decoding.
翻译:用于量子错误校正的经典解码管理费随着逻辑夸比特数量和校正代码距离而迅速增长。 室温解码被冰箱 I/ O 带宽的瓶盖封住, 而芯片的低温解码则受地区/电力/热预算的限制。 要克服这些间接费用, 我们的动力是观察到, 在常见情况( 超过90%的时间), 错误信号是相当微不足道的, 因为错误校正代码被过度提供, 以便能够校正异常最坏的复杂情景( 以确保逻辑误差率低得多 ) 。 如果适当利用这些微不足道的信号, 冰箱 I/ O 带宽带宽带低的带宽带宽带宽带宽带宽带宽带宽带宽, 同时仍然用最新科技手段处理最坏的情况。 我们的建议是: 1 用于解密/ 解码的轻度解码解码, 用于解码错误错误, 用于加密域。 解码的解码用于SFQQQ- 逻辑的解码比 。 2 以基于统计基础的解码技术, 解码的解码 解码系统解码前的解码, 解码系统解码技术, 的解路路路路路路路路路路的解法, 的解的解的解路路路路的解路的解路的解码法,,, 的解法,, 的解路的解所有。