标题： 受挫磁体的量子退火 显示英文标题

标题： Quantum annealing of a frustrated magnet

摘要： 量子退火，涉及可能解之间的量子隧穿，在快速找到复杂系统的最低能量配置以及量子计算中都有最先进的应用。 在这里，我们报告了一种单晶研究，即一种具有三角排列的铁磁伊辛自旋链的受挫磁体$\alpha$-CoV$_2$O$_6$，没有明显的结构无序。 我们观察到由于在微小横向场中的时间反演对称性破缺而产生的量子退火现象。 在 $\sim$ 1 K 以下，系统在零横向场中至少 15 小时内没有显示出接近最低能量状态的迹象，但在横向场为 $\sim$ 3.5 mK 的情况下，系统迅速收敛到该配置，其弛豫时间几乎与温度无关，为 $\sim$ 10 秒。 我们的多体模拟结果与实验结果定性一致，并表明微小的横向场可以显著增强量子自旋涨落，从而在低温下从拓扑亚稳的Kosterlitz-Thouless相触发快速的量子退火过程。 显示英文摘要

摘要： Quantum annealing, which involves quantum tunnelling among possible solutions, has state-of-the-art applications not only in quickly finding the lowest-energy configuration of a complex system, but also in quantum computing. Here we report a single-crystal study of the frustrated magnet $\alpha$-CoV$_2$O$_6$, consisting of a triangular arrangement of ferromagnetic Ising spin chains without evident structural disorder. We observe quantum annealing phenomena resulting from time-reversal symmetry breaking in a tiny transverse field. Below $\sim$ 1 K, the system exhibits no indication of approaching the lowest-energy state for at least 15 hours in zero transverse field, but quickly converges towards that configuration with a nearly temperature-independent relaxation time of $\sim$ 10 seconds in a transverse field of $\sim$ 3.5 mK. Our many-body simulations show qualitative agreement with the experimental results, and suggest that a tiny transverse field can profoundly enhance quantum spin fluctuations, triggering rapid quantum annealing process from topological metastable Kosterlitz-Thouless phases, at low temperatures.