近日，美国哈佛大学的Hengyun Zhou及其研究小组与美国芝加哥大学的Liang Jiang等人合作并取得一项新进展。经过不懈努力，他们实现具有可重构原子阵列的恒定负载容错量子计算。相关研究成果已于2024年4月29日在国际知名学术期刊《自然—物理学》上发表。
该研究团队提出一种硬件高效的方案，用于高速率qLDPC码的容错量子计算，该方案与最近证实的可重构原子阵列的能力兼容。该方法利用qLDPC码固有的乘积结构，通过原子重排实现非局部证候提取电路，有效维持了开销的稳定。研究人员已经证实了这些协议的容错性能，并通过模拟发现，基于qLDPC的架构在仅使用几百个物理量子比特的情况下，就开始展现出优于表面代码的性能。
他们进一步研究发现，涉及数千个逻辑量子比特的复杂量子算法，仅需不到105个物理量子比特即可执行。这项研究工作表明，使用当前的实验技术，qLDPC码的低开销量子计算是可以实现的。
据悉，量子低密度奇偶校验(qLDPC)码可以实现高编码率和良好的码距缩放，有可能实现低开销的容错量子计算。然而，实现qLDPC代码涉及非局部操作，需要量子比特之间的长程连接。这使得它们的物理实现与几何局部代码(如表面代码)相比具有挑战性。
附：英文原文
Title: Constant-overhead fault-tolerant quantum computation with reconfigurable atom arrays
Author: Xu, Qian, Bonilla Ataides, J. Pablo, Pattison, Christopher A., Raveendran, Nithin, Bluvstein, Dolev, Wurtz, Jonathan, Vasi, Bane, Lukin, Mikhail D., Jiang, Liang, Zhou, Hengyun
Issue&Volume: 2024-04-29
Abstract: Quantum low-density parity-check (qLDPC) codes can achieve high encoding rates and good code distance scaling, potentially enabling low-overhead fault-tolerant quantum computing. However, implementing qLDPC codes involves nonlocal operations that require long-range connectivity between qubits. This makes their physical realization challenging in comparison to geometrically local codes, such as the surface code. Here we propose a hardware-efficient scheme for fault-tolerant quantum computation with high-rate qLDPC codes that is compatible with the recently demonstrated capabilities of reconfigurable atom arrays. Our approach utilizes the product structure inherent in many qLDPC codes to implement the nonlocal syndrome extraction circuit through atom rearrangement, resulting in an effectively constant overhead. We prove the fault tolerance of these protocols, and our simulations show that the qLDPC-based architecture starts to outperform the surface code with as few as several hundred physical qubits. We further find that quantum algorithms involving thousands of logical qubits can be performed using less than 105 physical qubits. Our work suggests that low-overhead quantum computing with qLDPC codes is within reach using current experimental technologies.
DOI: 10.1038/s41567-024-02479-z
Source: https://www.nature.com/articles/s41567-024-02479-z