一种用于绝热核动力学的变分混合连续变量-离散变量量子算法
A variational hybrid continuous-variable discrete-variable quantum algorithm for adiabatic nuclear dynamics
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中文总结 AI 辅助
本研究提出变分混合CV-DV量子算法，在量子比特-振子硬件上模拟绝热核动力学，经测试可准确模拟多种一维系统的核动力学，为中等规模量子设备的分子动力学模拟提供路径。
中文摘要 AI 辅助
高斯波包（GWP）方法是在经典计算机上求解核含时薛定谔方程（TDSE）的主流手段，其核心是将核波函数表示为多个高斯函数的叠加。本文提出一种变分混合连续变量-离散变量（CV-DV）算法，用于在量子比特-振子量子硬件上模拟绝热核动力学，该算法将冻结高斯函数（FGs）的叠加编码到量子比特-振子寄存器中，并依据含时变分原理（VP）对其演化。我们在一组典型的一维简谐和非简谐系统上测试了该方法的两种变体：一种是单FG演化变体，另一种是FG叠加演化变体。我们使用该算法的单FG变体在物理量子硬件上模拟了二氧化硫（SO₂）的光激发态动力学并计算了其自相关函数；对于简谐势和莫尔斯势，FG叠加演化变体随着高斯函数数量的增加收敛到数值精确解；对于双势阱势，该算法能正确模拟波包的分岔与重现，且对后续不规则动力学的模拟效果良好。总体而言，本研究为在噪声中等规模量子设备上模拟分子动力学奠定了路径。
英文摘要
Gaussian wavepacket (GWP) methods are prevalent means of solving the nuclear time-dependent Schrodinger equation (TDSE) on classical computers. They consist of representing the nuclear wave function as a superposition of Gaussians. Here, we present a variational hybrid continuous-variable discrete-variable (CV-DV) algorithm for simulating adiabatic nuclear dynamics on qubit-oscillator quantum hardware. It encodes a superposition of frozen Gaussians (FGs) onto the qubit-oscillator register and evolves it according to the time-dependent variational principle (VP). We test two variants of the approach, one that evolves a single FG and another that evolves a superposition of FGs, on a set of prototypical 1D harmonic and anharmonic systems. We simulate the photoexcited state dynamics of SO2 using the single FG variant of the algorithm and compute its autocorrelation function on physical quantum hardware. For harmonic and Morse potentials, the variant evolving the superposition of FGs converges to the numerically exact solution as the number of Gaussians increases. In the case of the double-well potential, the algorithm simulates wavepacket bifurcation and recurrence correctly, and the ensuing irregular dynamics moderately well. Overall, this work establishes a pathway for simulating molecular dynamics on noisy intermediate-scale quantum devices.
