CutQC: using small Quantum computers for large Quantum circuit evaluations
CutQC: using small Quantum computers for large Quantum circuit evaluations
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DOI：
10.1145/3445814.3446758
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发表时间：
2020-12
期刊：
影响因子：
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通讯作者：
Wei Tang;T. Tomesh;Jeffrey Larson;Martin Suchara;M. Martonosi
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文献类型：
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作者：
Wei Tang;T. Tomesh;Jeffrey Larson;Martin Suchara;M. Martonosi
量子计算（QC）是一种新的范式，为某些计算问题提供了比经典计算指数加速的潜力。每个额外的量子位使QC算法可用的计算状态空间的大小加倍。这种指数级扩展是QC能力的基础，但当今的噪声中等规模量子（NISQ）器件在可扩展性方面面临着重大的工程挑战。可以在NISQ设备上可靠运行的量子电路集受到其噪声操作和低量子比特计数的限制。本文介绍了CutQC，这是一种可扩展的混合计算方法，它结合了经典计算机和量子计算机，可以评估无法单独在经典计算机或量子计算机上运行的量子电路。CutQC将大型量子电路切割成较小的子电路，使它们能够在较小的量子设备上执行。然后，经典的后处理可以重建原始电路的输出。这种方法提供了显着的运行时加速相比，唯一可行的电流替代纯经典模拟，并演示了量子电路的评估大于QC或经典模拟的限制。此外，在实际系统运行中，CutQC使用小型原型量子计算机实现了比最先进的大型NISQ设备更高的量子电路评估保真度。总的来说，这种混合方法允许用户利用经典和量子计算资源来评估远远超出任何一个单独的量子程序。
Quantum computing (QC) is a new paradigm offering the potential of exponential speedups over classical computing for certain computational problems. Each additional qubit doubles the size of the computational state space available to a QC algorithm. This exponential scaling underlies QC’s power, but today’s Noisy Intermediate-Scale Quantum (NISQ) devices face significant engineering challenges in scalability. The set of quantum circuits that can be reliably run on NISQ devices is limited by their noisy operations and low qubit counts. This paper introduces CutQC, a scalable hybrid computing approach that combines classical computers and quantum computers to enable evaluation of quantum circuits that cannot be run on classical or quantum computers alone. CutQC cuts large quantum circuits into smaller subcircuits, allowing them to be executed on smaller quantum devices. Classical postprocessing can then reconstruct the output of the original circuit. This approach offers significant runtime speedup compared with the only viable current alternative—purely classical simulations—and demonstrates evaluation of quantum circuits that are larger than the limit of QC or classical simulation. Furthermore, in real-system runs, CutQC achieves much higher quantum circuit evaluation fidelity using small prototype quantum computers than the state-of-the-art large NISQ devices achieve. Overall, this hybrid approach allows users to leverage classical and quantum computing resources to evaluate quantum programs far beyond the reach of either one alone.