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arXiv 1907.04769quant-ph
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基于CVaR的变分量子优化算法

Improving Variational Quantum Optimization using CVaR

Panagiotis Kl. Barkoutsos, Giacomo Nannicini, Anton Robert, Ivano Tavernelli, Stefan Woerner

摘要:

混合量子/经典变分算法可以在有噪声的中等规模量子计算机上实现,并且可以用于找到组合优化问题的解决方案。在文献中讨论的方法最小化的期望的问题的哈密顿量的参数化试验量子态。期望值被估计为一组测量结果的样本均值,而试验状态的参数被经典地优化。这个过程对于量子力学的可观测量,如分子能量,是完全合理的。在经典优化问题的情况下,产生对角哈密顿算子,我们认为,以不同的方式比期望值的样本聚合是更自然的。在本文中,我们提出了条件风险价值作为一个聚集函数。我们经验表明-使用经典模拟以及量子硬件-这导致更快的收敛到更好的解决方案,在我们的研究中测试的所有组合优化问题。我们还提供了分析结果来解释观察到的不同变分算法之间的性能差异。

英文摘要:

Hybrid quantum/classical variational algorithms can be implemented on noisy intermediate-scale quantum computers and can be used to find solutions for combinatorial optimization problems. Approaches discussed in the literature minimize the expectation of the problem Hamiltonian for a parameterized trial quantum state. The expectation is estimated as the sample mean of a set of measurement outcomes, while the parameters of the trial state are optimized classically. This procedure is fully justified for quantum mechanical observables such as molecular energies. In the case of classical optimization problems, which yield diagonal Hamiltonians, we argue that aggregating the samples in a different way than the expected value is more natural. In this paper we propose the Conditional Value-at-Risk as an aggregation function. We empirically show -- using classical simulation as well as quantum hardware -- that this leads to faster convergence to better solutions for all combinatorial optimization problems tested in our study. We also provide analytical results to explain the observed difference in performance between different variational algorithms.

机构、总结、中文摘要均由AI分析而来,可能存在错误,请以论文正文为准。

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