论文标题
统一分区和上下文子空间变分量子本质量
Unitary Partitioning and the Contextual Subspace Variational Quantum Eigensolver
论文作者
论文摘要
上下文子空间变分量子本质量(CS-VQE)是一种杂交量子古典算法,近似于给定的Qubit Hamiltonian的地面能量。它通过将哈密顿量分为上下文和非副本部分来实现这一目标。通过经典解决非上下文问题的基础能量近似,然后使用VQE解决上下文问题,并受到非上下文解决方案的约束。通常,与通过传统VQE解决完整的哈密顿量相比,上下文校正的计算需要更少的量子和测量。我们在不同的锥形分子哈密顿量上模拟CS-VQE,并应用单一分配测量策略,以进一步减少获得上下文校正所需的测量数量。我们的结果表明,CS-VQE与测量降低相结合是一种有前途的方法,可以允许对嘈杂的中等规模量子设备进行可行的特征值计算。我们还为CS-VQE算法提供了修改;以前的CS-VQE算法可能会导致哈密顿术语的指数增加,但是随着这种修改现在最坏的情况将四次扩展。
The contextual subspace variational quantum eigensolver (CS-VQE) is a hybrid quantum-classical algorithm that approximates the ground-state energy of a given qubit Hamiltonian. It achieves this by separating the Hamiltonian into contextual and noncontextual parts. The ground-state energy is approximated by classically solving the noncontextual problem, followed by solving the contextual problem using VQE, constrained by the noncontextual solution. In general, computation of the contextual correction needs fewer qubits and measurements compared with solving the full Hamiltonian via traditional VQE. We simulate CS-VQE on different tapered molecular Hamiltonians and apply the unitary partitioning measurement reduction strategy to further reduce the number of measurements required to obtain the contextual correction. Our results indicate that CS-VQE combined with measurement reduction is a promising approach to allow feasible eigenvalue computations on noisy intermediate-scale quantum devices. We also provide a modification to the CS-VQE algorithm; the CS-VQE algorithm previously could cause an exponential increase in Hamiltonian terms, but with this modification now at worst will scale quadratically.