Copenhaver Justin, Wasserman Adam, Wehefritz-Kaufmann Birgit
Department of Physics and Astronomy, Purdue University, West Lafayette, Indiana 47907, USA.
J Chem Phys. 2021 Jan 21;154(3):034105. doi: 10.1063/5.0030397.
Quantum annealers are an alternative approach to quantum computing, which make use of the adiabatic theorem to efficiently find the ground state of a physically realizable Hamiltonian. Such devices are currently commercially available and have been successfully applied to several combinatorial and discrete optimization problems. However, the application of quantum annealers to problems in chemistry remains a relatively sparse area of research due to the difficulty in mapping molecular systems to the Ising model Hamiltonian. In this paper, we review two different methods for finding the ground state of molecular Hamiltonians using Ising model-based quantum annealers. In addition, we compare the relative effectiveness of each method by calculating the binding energies, bond lengths, and bond angles of the H and HO molecules and mapping their potential energy curves. We also assess the resource requirements of each method by determining the number of qubits and computation time required to simulate each molecule using various parameter values. While each of these methods is capable of accurately predicting the ground state properties of small molecules, we find that they are still outperformed by modern classical algorithms and that the scaling of the resource requirements remains a challenge.
量子退火器是量子计算的一种替代方法，它利用绝热定理来有效地找到物理上可实现的哈密顿量的基态。这类设备目前已商业化，并且已成功应用于多个组合和离散优化问题。然而，由于难以将分子系统映射到伊辛模型哈密顿量，量子退火器在化学问题中的应用仍然是一个相对较少研究的领域。在本文中，我们回顾了两种使用基于伊辛模型的量子退火器来寻找分子哈密顿量基态的不同方法。此外，我们通过计算H₂和H₂O分子的结合能、键长和键角并绘制它们的势能曲线，比较了每种方法的相对有效性。我们还通过确定使用各种参数值模拟每个分子所需的量子比特数和计算时间，评估了每种方法的资源需求。虽然这些方法中的每一种都能够准确预测小分子的基态性质，但我们发现它们仍然不如现代经典算法，并且资源需求的扩展仍然是一个挑战。
