论文标题
使用VQE方法模拟阴极电池材料的过渡金属氧化物
Towards the simulation of transition-metal oxides of the cathode battery materials using VQE methods
论文作者
论文摘要
变性量子本质量（VQE）是一种混合量子古典技术，利用嘈杂的中间尺度量子（NISQ）硬件来获得模型汉密尔顿模型的最低特征值。到目前为止，VQE已被用于模拟凝结物质系统以及小分子的量子化学。在这项工作中，我们采用VQE方法来获取Licoo $ _2 $的基础能量，这是一种用于电池阴极的候选过渡金属氧化物。我们模拟了李$ _2 $ co $ _2 $ o $ _4 $和CO $ _2 $ o $ $ _4 $ $ _4 $气相型号，该型号分别代表放电期间的固定状态和划定状态和锂离子电池的充电。使用具有单个参考状态的状态向量模拟器进行三种不同试验波函数进行计算：单一耦合群集单打和双打（UCCSD），单一耦合群集群集通用单打和双打（UCCGSD）（UCCGSD）和K-独立成对的成对成对成对的单身单身单曲和Doubleds and Doublecs（K-k-upccsd）。分析了在电路深度，两倍的纠缠门和波函数参数方面的资源。我们发现具有K = 5的K-UpCCGSD产生的结果类似于UCCSD，但成本较低。最后，VQE方法的性能是针对基于经典波函数的方法的基准测试的，例如耦合群集单打和双打（CCSD）和完整的主动空间配置交互（CASCI）。我们的结果表明，VQE方法与从CCSD获得的结果定量一致。但是，与CASCI结果的比较清楚地表明，高级试验波函数对于捕获多引用特征以及高级电子激发产生的相关性可能是必要的。
Variational quantum eigensolver (VQE) is a hybrid quantum-classical technique that leverages noisy intermediate scale quantum (NISQ) hardware to obtain the minimum eigenvalue of a model Hamiltonian. VQE has so far been used to simulate condensed matter systems as well as quantum chemistry of small molecules. In this work, we employ VQE methods to obtain the ground-state energy of LiCoO$_2$, a candidate transition metal oxide used for battery cathodes. We simulate Li$_2$Co$_2$O$_4$ and Co$_2$O$_4$ gas-phase models, which represent the lithiated and delithiated states during the discharge and the charge of the Li-ion battery, respectively. Computations are performed using a statevector simulator with a single reference state for three different trial wavefunctions: unitary coupled-cluster singles and doubles (UCCSD), unitary coupled-cluster generalized singles and doubles (UCCGSD) and k-unitary pair coupled-cluster generalized singles and doubles (k-UpCCGSD). The resources in terms of circuit depth, two-qubit entangling gates and wavefunction parameters are analyzed. We find that the k-UpCCGSD with k=5 produces results similar to UCCSD but at a lower cost. Finally, the performance of VQE methods is benchmarked against the classical wavefunction-based methods, such as coupled-cluster singles and doubles (CCSD) and complete active space configuration interaction (CASCI). Our results show that VQE methods quantitatively agree with the results obtained from CCSD. However, the comparison against the CASCI results clearly suggests that advanced trial wavefunctions are likely necessary to capture the multi-reference characteristics as well as the correlations emerging from high-level electronic excitations.
