论文标题

Adapt-VQE对粗糙的参数景观和贫瘠的高原不敏感

ADAPT-VQE is insensitive to rough parameter landscapes and barren plateaus

论文作者

Grimsley, Harper R., Barron, George S., Barnes, Edwin, Economou, Sophia E., Mayhall, Nicholas J.

论文摘要

变性量子本素(VQE)代表用于计算分子能量的强大的杂化量子古典算法。但是,这些方法存在各种数值问题,包括贫瘠的高原和大量局部最小值。在这项工作中,我们考虑了自适应,问题的(Adapt)-VQEAnsätze,并检查它们如何受到这些本地最小值的影响。我们发现,虽然Adapt-VQE无法删除本地最小值,但梯度信息,单操作的循环构造似乎可以完成两件事:首先,它提供了一种初始化策略,该策略比随机初始化更好,并且适用于化学直觉无法帮助的情况下,即在较差的情况下,较差的距离是一个较差的距离。其次,即使Autapt-VQE迭代在一个步骤中会收敛到局部陷阱,它仍然可以通过添加更多的操作员来“钻入”精确解决方案,从而优先加深被占用的陷阱。相同的机制有助于强调Adapt-VQE的惊人特征:由于“贫瘠的高原”,它不应遭受优化问题。即使贫瘠的高原出现在参数景观中,我们的分析和模拟表明,Adapt-VQE避免了设计区域。

Variational quantum eigensolvers (VQEs) represent a powerful class of hybrid quantum-classical algorithms for computing molecular energies. Various numerical issues exist for these methods, however, including barren plateaus and large numbers of local minima. In this work, we consider Adaptive, Problem-Tailored (ADAPT)-VQE ansätze, and examine how they are impacted by these local minima. We find that while ADAPT-VQE does not remove local minima, the gradient-informed, one-operator-at-a-time circuit construction seems to accomplish two things: First, it provides an initialization strategy that is dramatically better than random initialization, and which is applicable in situations where chemical intuition cannot help with initialization, i.e., when Hartree-Fock is a poor approximation to the ground state. Second, even if an ADAPT-VQE iteration converges to a local trap at one step, it can still "burrow" toward the exact solution by adding more operators, which preferentially deepens the occupied trap. This same mechanism helps highlight a surprising feature of ADAPT-VQE: It should not suffer optimization problems due to "barren plateaus". Even if barren plateaus appear in the parameter landscape, our analysis and simulations reveal that ADAPT-VQE avoids such regions by design.

扫码加入交流群

加入微信交流群

微信交流群二维码

扫码加入学术交流群,获取更多资源