We present a quantum chemistry benchmark for noisy intermediate-scale quantum computers that leverages the variational quantum eigensolver, active-space reduction, a reduced unitary coupled cluster ansatz, and reduced density purification as error mitigation. We demonstrate this benchmark using 4 of the available qubits on the 20-qubit IBM Tokyo and 16-qubit Rigetti Aspen processors via the simulation of alkali metal hydrides (NaH, KH, RbH), with accuracy of the computed ground state energy serving as the primary benchmark metric. We further parameterize this benchmark suite on the trial circuit type, the level of symmetry reduction, and error mitigation strategies. Our results demonstrate the characteristically high noise level present in near-term superconducting hardware, but provide a relevant baseline for future improvement of the underlying hardware, and a means for comparison across near-term hardware types. We also demonstrate how to reduce the noise in post processing with specific error mitigation techniques. Particularly, the adaptation of McWeeny purification of noisy density matrices dramatically improves accuracy of quantum computations, which, along with adjustable active space, significantly extends the range of accessible molecular systems. We demonstrate that for specific benchmark settings and a selected range of problems, the accuracy metric can reach chemical accuracy when computing over the cloud on certain quantum computers.

我们为嘈杂的中型量子计算机提供了一个量子化学基准，该基准利用了变分量子本征求解器，有效空间减少，减少的unit耦合簇ansatz和减少的密度提纯作为错误缓解措施。我们通过模拟碱金属氢化物（NaH，KH，RbH），使用20量子位IBM Tokyo和16量子位Rigetti Aspen处理器上的4个可用量子位，证明了该基准，并以计算出的基态能量的准确性作为主要基准指标。我们进一步根据试验电路类型，对称性降低的水平和错误缓解策略对这个基准套件进行参数化。我们的结果证明了近期超导硬件中存在的特征性高噪声水平，但为将来的基础硬件改进提供了相关的基准，并为近期硬件类型之间的比较提供了一种方法。我们还演示了如何使用特定的错误缓解技术来减少后期处理中的噪声。特别是，对嘈杂密度矩阵的McWeeny纯化的适应性极大地提高了量子计算的准确性，这与可调整的活动空间一起极大地扩展了可访问分子系统的范围。我们证明，对于特定的基准设置和选定的问题范围，在某些量子计算机上通过云计算时，精度指标可以达到化学精度。特别是，对嘈杂密度矩阵的McWeeny纯化的适应性极大地提高了量子计算的准确性，这与可调整的活动空间一起极大地扩展了可访问分子系统的范围。我们证明，对于特定的基准设置和选定的问题范围，在某些量子计算机上通过云计算时，精度指标可以达到化学精度。特别是，对嘈杂密度矩阵的McWeeny纯化的适应性极大地提高了量子计算的准确性，这与可调整的活动空间一起极大地扩展了可访问分子系统的范围。我们证明，对于特定的基准设置和选定的问题范围，在某些量子计算机上通过云计算时，精度指标可以达到化学精度。