线性光学量子计算中子电路编译的不完美性处理

中文摘要 AI 辅助

线性光学量子计算（LOQC）正成为大规模量子计算中一项有前景的技术。相应的设备，包括线性光学电路，在尺寸和制造精度上正在快速增长。然而，即使质量有所提高，电路仍表现出缺陷，导致光子损失或相位噪声，且这些缺陷在电路中各处不同。即使是微小的缺陷也会对准确性和效率产生巨大影响。对于不需要整个线性光学电路的计算，即所谓的子电路，可以选择在何处执行计算，这开启了子电路编译所解决的优化机会。当前的编译器将子电路的计算分散到整个电路上，连接相同的输入和输出端口，从而未能充分利用优化机会。然而，鉴于子电路相对于整个电路尺寸较小，可以将其实现保持局部化，并有意路由光子以连接良好的输入和输出端口。然而，这是一项高度非平凡的任务，因为必须权衡众多选项，且解决方案的质量受多种硬件参数影响。特别是，不完美分束器的反射率可能导致路由过程中的光子损失，这必须与因不完美传输率导致的输入和输出端口损失进行权衡。由于当前编译器未考虑这些效应，我们提出了首个高效的子电路编译方法，通过处理硬件不完美性来优化符合率，即成功测量所有期望光子的概率。我们的评估表明，在对抗相位噪声的鲁棒性方面，该方法显著优于现有方法，并在所有基准测试中将符合率大幅提高，最高达33.2%。

英文摘要

Linear Optical Quantum Computing (LOQC) is emerging as a promising technology in large-scale quantum computing. Corresponding devices, including linear optical circuits, are rapidly growing in size and fabrication precision. However, even with improved quality, the circuits still exhibit imperfections leading to photon loss or phase noise that vary across the circuit. Already small deficiencies can have a vast impact on both accuracy and efficiency. For computations that do not require the entire linear optical circuit, so-called subcircuits, one can choose where to perform the computation, opening optimization opportunities that are addressed by subcircuit compilation. Current compilers spread the subcircuit's computation across the entire circuit, connecting the same input and output ports, thereby failing to fully exploit the optimization opportunities. However, given the subcircuit's reduced size compared to the entire circuit, one can keep its implementation localized and intentionally route photons to connect good input and output ports. This, however, is a highly non-trivial task, as numerous options must be weighed against one another, and the quality of the solution is influenced by a wide range of hardware parameters. In particular, the reflectivities of imperfect beam splitters can lead to photon losses during routing, which must be traded off against losses at the input and output ports due to imperfect transmission rates. Since current compilers do not account for these effects, we propose the first efficient subcircuit compilation method that optimizes for the coincidence rate, the probability of successfully measuring all desired photons, by handling hardware imperfections. Our evaluations demonstrate significant improvement over existing methods in robustness against phase noise and significantly increased coincidence rates across all benchmarks of up to plus 33.2%.

发表机构

• Technical University of Munich（慕尼黑工业大学）
• MQSC, Garching near Munich（慕尼黑附近加兴的MQSC）
• Quandela, Massy（马西的Quandela）

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