论文标题
改进的量子计算通过高阶棍子分解
Improved Quantum Computing with the Higher-order Trotter Decomposition
论文作者
论文摘要
在设计量子控制时，通常需要使用经典计算机模拟受控的系统演变。但是，计算时间演化运算符可能会非常重要，因为总的哈密顿量通常很难对角度化。在本文中，我们通过将时间演化段用猪肉分解来替代时间，从而减轻了这个问题，从而将传播器减少为单量操作和固定时间系统演变的组合。最终的过程可以在传播器错误中提供可接受的成本，从而提供大量速度增益。作为演示，我们应用了提出的策略来提高梯度上升脉冲工程算法的效率，以搜索最佳控制场。此外，我们表明，高阶猪肉分解可以为变异量子算法提供有效的Ansätze，从而改善了解决地面问题的性能。此处介绍的策略也适用于许多其他量子优化和仿真任务。
In designing quantum control, it is generally required to simulate the controlled system evolution with a classical computer. However, computing the time evolution operator can be quite resource-consuming since the total Hamiltonian is often hard to diagonalize. In this paper, we mitigate this issue by substituting the time evolution segments with their Trotter decompositions, which reduces the propagator into a combination of single-qubit operations and fixed-time system evolutions. The resulting procedure can provide substantial speed gain with acceptable costs in the propagator error. As a demonstration, we apply the proposed strategy to improve the efficiency of the gradient ascent pulse engineering algorithm for searching optimal control fields. Furthermore, we show that the higher-order Trotter decompositions can provide efficient Ansätze for the variational quantum algorithm, leading to improved performance in solving the ground-state problem. The strategy presented here is also applicable for many other quantum optimization and simulation tasks.
