论文标题
一种国家平均轨道优化的杂种量子古典算法,用于对地面和激动国家的民主描述
A state-averaged orbital-optimized hybrid quantum-classical algorithm for a democratic description of ground and excited states
论文作者
论文摘要
在嘈杂的中间量子量子(NISQ)时代,从化学中解决电子结构问题被认为是近期量子设备的“杀手级应用”。尽管变异杂种量子/经典算法在为小分子提供准确的能量曲线方面取得了成功,但仍需要仔细考虑,以描述势能表面的复杂特征。由于当前的量子资源非常有限,因此通常专注于希尔伯特空间的限制部分(由一组活跃的轨道决定)。尽管出于身体的动力,但这种近似可能会严重影响这些复杂特征的描述。一个完美的例子是圆锥形交叉点(即电子状态之间的堕落性奇异点),这对于理解许多突出反应至关重要。设计主动空间,以便没有毫无用处地从量子计算机中提高准确性,这是在化学领域中找到这些有前途的设备的有用应用的关键。为了回答这个问题,我们介绍了一种称为“国家平均轨道优化的变异量子本质量”(sa-oo-oo-vQe)的方法,该方法结合了两种算法:(1)一种状态范围的轨道轨道示例器,以及(2)状态范围的VQE。为了证明该方法的成功,我们在最小的Schiff碱模型(即甲醛胺分子CH2NH)上进行了古典模拟,这也与Rhodopsin中的光异构化相关 - 在视觉过程中,这是由圆锥形交叉点的存在介导的视觉过程中的关键步骤。我们表明,合并这两种算法都满足了描述分子圆锥形交叉点的必要条件,即在同一基础上处理退化(或准排分)状态的能力。
In the Noisy Intermediate-Scale Quantum (NISQ) era, solving the electronic structure problem from chemistry is considered as the "killer application" for near-term quantum devices. In spite of the success of variational hybrid quantum/classical algorithms in providing accurate energy profiles for small molecules, careful considerations are still required for the description of complicated features of potential energy surfaces. Because the current quantum resources are very limited, it is common to focus on a restricted part of the Hilbert space (determined by the set of active orbitals). While physically motivated, this approximation can severely impact the description of these complicated features. A perfect example is that of conical intersections (i.e. a singular point of degeneracy between electronic states), which are of primary importance to understand many prominent reactions. Designing active spaces so that the improved accuracy from a quantum computer is not rendered useless is key to finding useful applications of these promising devices within the field of chemistry. To answer this issue, we introduce a NISQ-friendly method called "State-Averaged Orbital-Optimized Variational Quantum Eigensolver" (SA-OO-VQE) which combines two algorithms: (1) a state-averaged orbital-optimizer, and (2) a state-averaged VQE. To demonstrate the success of the method, we classically simulate it on a minimal Schiff base model (namely the formaldimine molecule CH2NH) relevant also for the photoisomerization in rhodopsin -- a crucial step in the process of vision mediated by the presence of a conical intersection. We show that merging both algorithms fulfil the necessary condition to describe the molecule's conical intersection, i.e. the ability to treat degenerate (or quasi-degenerate) states on the same footing.