Teplukhin Alexander, Kendrick Brian K, Babikov Dmitri
Theoretical Division (T-1, MS B221) , Los Alamos National Laboratory , Los Alamos , New Mexico 87545 , United States.
Department of Chemistry , Marquette University , Milwaukee , Wisconsin 53021 , United States.
J Chem Theory Comput. 2019 Aug 13;15(8):4555-4563. doi: 10.1021/acs.jctc.9b00402. Epub 2019 Aug 1.
Until recently molecular energy calculations using quantum computing hardware have been limited to gate-based quantum computers. In this paper, a new methodology is presented to calculate the vibrational spectrum of a molecule on a quantum annealer. The key idea of the method is a mapping of the ground state variational problem onto an Ising or quadratic unconstrained binary optimization (QUBO) problem by expressing the expansion coefficients using spins or qubits. The algorithm is general and represents a new revolutionary approach for solving the real symmetric eigenvalue problem on a quantum annealer. The method is applied to two chemically important molecules: O (oxygen) and O (ozone). The lowest two vibrational states of these molecules are computed using both a hardware quantum annealer and a software based classical annealer. Extension of the algorithm to higher dimensions is explicitly demonstrated for an -dimensional harmonic oscillator ( ≤ 5). The algorithm scales exponentially with dimensionality if a direct product basis is used but will exhibit polynomial scaling for a nondirect product basis.
直到最近，使用量子计算硬件进行的分子能量计算还仅限于基于门的量子计算机。本文提出了一种在量子退火器上计算分子振动光谱的新方法。该方法的关键思想是通过用自旋或量子比特表示展开系数，将基态变分问题映射到伊辛或二次无约束二元优化（QUBO）问题上。该算法具有通用性，代表了一种在量子退火器上解决实对称特征值问题的全新革命性方法。该方法应用于两种具有化学重要性的分子：O（氧气）和O₃（臭氧）。使用硬件量子退火器和基于软件的经典退火器计算了这些分子的最低两个振动态。对于一个n维（n≤5）的谐振子，明确展示了该算法向更高维度的扩展。如果使用直积基，该算法随维度呈指数缩放，但对于非直积基将呈现多项式缩放。
