论文标题
量子化学的有效级别量子假想时间演变算法
Efficient step-merged quantum imaginary time evolution algorithm for quantum chemistry
论文作者
论文摘要
我们开发了一种资源有效的阶梯量子假想时间演化方法（SMQITE），以求解量子计算机上的哈密顿量的基态。这种启发式方法具有沿状态进化路径的固定浅量子电路深度。我们使用该算法来确定一组分子的绑定能曲线，包括h $ _2 $，h $ _4 $，h $ _6 $，lih，hf，hf，h $ _2 $ o和beh $ _2 $，并找到高度准确的结果。可以通过采用各种量子本质量（VQE）技术的电路形式，例如单一耦合群集ANSATZ来进一步降低Smqite计算所需的量子资源。我们证明，Smqite在同一固定电路Ansatz上具有与VQE相似的计算精度，而无需通常的高维非凸优化。最后，在Rigetti量子处理单元（QPU）上进行SMQITE计算，表明该方法很容易适用于当前噪声中间尺度量子（NISQ）设备。
We develop a resource efficient step-merged quantum imaginary time evolution approach (smQITE) to solve for the ground state of a Hamiltonian on quantum computers. This heuristic method features a fixed shallow quantum circuit depth along the state evolution path. We use this algorithm to determine binding energy curves of a set of molecules, including H$_2$, H$_4$, H$_6$, LiH, HF, H$_2$O and BeH$_2$, and find highly accurate results. The required quantum resources of smQITE calculations can be further reduced by adopting the circuit form of the variational quantum eigensolver (VQE) technique, such as the unitary coupled cluster ansatz. We demonstrate that smQITE achieves a similar computational accuracy as VQE at the same fixed-circuit ansatz, without requiring a generally complicated high-dimensional non-convex optimization. Finally, smQITE calculations are carried out on Rigetti quantum processing units (QPUs), demonstrating that the approach is readily applicable on current noisy intermediate-scale quantum (NISQ) devices.
