Resolving correlated states of benzyne with an error-mitigated contracted quantum eigensolver
Resolving correlated states of benzyne with an error-mitigated contracted quantum eigensolver
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DOI：
10.1103/physreva.105.022405
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发表时间：
2021-03
影响因子：
2.9
通讯作者：
Scott E. Smart;Jan-Niklas Boyn;D. Mazziotti
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文献类型：
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作者：
Scott E. Smart;Jan-Niklas Boyn;D. Mazziotti
强关联多电子系统的模拟是近期量子器件最有前途的应用之一。在这里，我们使用一类本征值求解器(在物理中提出。莱特牧师。126,070504(2021年)，其中，收缩的薛定谔方程被求解为双电子约化密度矩阵(2-RDM)，以解决苯并炔的正异构体、偏异构体和对位异构体的能量分裂。与传统的变分量子本征解不同，压缩量子本征解解决了多电子薛定谔方程在双电子空间的积分(或收缩)。压缩薛定谔方程(QACSE)反厄米特部分的量子解提供了一种基于2-RDM理论的变参数可伸缩方法。在实验上，各种误差缓解策略使计算成为可能，包括针对算法的迭代性质的2-RDM的线性移位，以及将2-RDM投影到由2-正(DQG)$N$-可表示条件定义的约$N$-可表示的2-RDM的凸集上。相对能量表现出一位数的毫哈特里误差，捕获了很大一部分电子关联能量，计算的自然轨道占据反映了异构体电子关联的显著差异。
The simulation of strongly correlated many-electron systems is one of the most promising applications for near-term quantum devices. Here we use a class of eigenvalue solvers (presented in Phys. Rev. Lett. 126, 070504 (2021)) in which a contraction of the Schr\"odinger equation is solved for the two-electron reduced density matrix (2-RDM) to resolve the energy splittings of ortho-, meta-, and para-isomers of benzyne ${\textrm C_6} {\textrm H_4}$. In contrast to the traditional variational quantum eigensolver, the contracted quantum eigensolver solves an integration (or contraction) of the many-electron Schr\"odinger equation onto the two-electron space. The quantum solution of the anti-Hermitian part of the contracted Schr\"odinger equation (qACSE) provides a scalable approach with variational parameters that has its foundations in 2-RDM theory. Experimentally, a variety of error mitigation strategies enable the calculation, including a linear shift in the 2-RDM targeting the iterative nature of the algorithm as well as a projection of the 2-RDM onto the convex set of approximately $N$-representable 2-RDMs defined by the 2-positive (DQG) $N$-representability conditions. The relative energies exhibit single-digit millihartree errors, capturing a large part of the electron correlation energy, and the computed natural orbital occupations reflect the significant differences in the electron correlation of the isomers.