论文标题

通过稳定的幅度估计,降低变异量子本特征算法的能量估计成本

Reducing the cost of energy estimation in the variational quantum eigensolver algorithm with robust amplitude estimation

论文作者

Johnson, Peter D., Kunitsa, Alexander A., Gonthier, Jérôme F., Radin, Maxwell D., Buda, Corneliu, Doskocil, Eric J., Abuan, Clena M., Romero, Jhonathan

论文摘要

量子化学和材料是量子计算最有希望的应用之一。然而,在这些领域中与行业相关的问题的量子算法可以解决这些问题的问题仍然可以完成许多工作。以前的大多数努力都对量子算法进行了资源估计,该算法在大规模的耐断层体系结构上进行,其中包括量子相估计算法。相比之下,很少有人评估了近期量子算法的性能,其中包括变异量子本元素(VQE)算法。最近,一项大规模的基准研究[Gonthier等。 [2020年]发现证据表明,一组与行业相关的分子的变异量子本质量的性能可能太低效率而无法实际使用。这激发了开发和评估提高VQE效率的方法的需求。在这项工作中,我们可以预测,当使用强大的振幅估计(RAE)估算Pauli的预期值时,VQE的能量估计子例程的运行时间。在保守的假设下,我们的资源估计预测,RAE可以将运行时与VQE中的标准估计方法相比,将运行时间降低一到两个数量级。尽管有这种改进,但我们发现运行时间仍然太大而无法实用。这些发现激发了量子优势的两种互补努力:1)对基础状态估计的更有效的近期方法的调查; 2)发展具有工业价值和经典挑战的问题实例的发展,但更适合量子计算。

Quantum chemistry and materials is one of the most promising applications of quantum computing. Yet much work is still to be done in matching industry-relevant problems in these areas with quantum algorithms that can solve them. Most previous efforts have carried out resource estimations for quantum algorithms run on large-scale fault-tolerant architectures, which include the quantum phase estimation algorithm. In contrast, few have assessed the performance of near-term quantum algorithms, which include the variational quantum eigensolver (VQE) algorithm. Recently, a large-scale benchmark study [Gonthier et al. 2020] found evidence that the performance of the variational quantum eigensolver for a set of industry-relevant molecules may be too inefficient to be of practical use. This motivates the need for developing and assessing methods that improve the efficiency of VQE. In this work, we predict the runtime of the energy estimation subroutine of VQE when using robust amplitude estimation (RAE) to estimate Pauli expectation values. Under conservative assumptions, our resource estimation predicts that RAE can reduce the runtime over the standard estimation method in VQE by one to two orders of magnitude. Despite this improvement, we find that the runtimes are still too large to be practical. These findings motivate two complementary efforts towards quantum advantage: 1) the investigation of more efficient near-term methods for ground state energy estimation and 2) the development of problem instances that are of industrial value and classically challenging, but better suited to quantum computation.

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