论文标题

用对称子空间进行量子退火

Quantum annealing with symmetric subspaces

论文作者

Imoto, Takashi, Seki, Yuya, Matsuzaki, Yuichiro

论文摘要

量子退火(QA)不仅是解决组合优化问题,还可以模拟量子多体系统(例如凝结物质物理学的量子系统)的一种有前途的方法。但是,非绝热过渡构成了质量检查中的主要挑战。已知驱动器的选择会影响质量检查的性能,因为可能会抑制非绝热过渡。在这里,我们提出了使用驱动汉密尔顿的使用,该驱动器保留了哈密顿式问题的对称性,以提高质量质量。由于我们选择了驱动哈密顿量,在质量保证期间,在适当的对称子空间中搜索了解决方案。由于非绝热过渡仅发生在特定子空间内,因此我们的方法可能会抑制不必要的非绝热过渡。为了评估我们计划的性能,我们采用XY模型作为驱动哈密顿式的驱动器,以找到问题的基础状态汉密尔顿人,这些状态沿$ z $轴的总磁化通勤。我们发现,根据目标基态和质量保证金之间的忠诚度,我们的计划优于常规计划。

Quantum annealing (QA) is a promising approach for not only solving combinatorial optimization problems but also simulating quantum many-body systems such as those in condensed matter physics. However, non-adiabatic transitions constitute a key challenge in QA. The choice of the drive Hamiltonian is known to affect the performance of QA because of the possible suppression of non-adiabatic transitions. Here, we propose the use of a drive Hamiltonian that preserves the symmetry of the problem Hamiltonian for more efficient QA. Owing to our choice of the drive Hamiltonian, the solution is searched in an appropriate symmetric subspace during QA. As non-adiabatic transitions occur only inside the specific subspace, our approach can potentially suppress unwanted non-adiabatic transitions. To evaluate the performance of our scheme, we employ the XY model as the drive Hamiltonian in order to find the ground state of problem Hamiltonians that commute with the total magnetization along the $z$ axis. We find that our scheme outperforms the conventional scheme in terms of the fidelity between the target ground state and the states after QA.

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