论文标题
观察外部磁场中受对称保护的拓扑阶段
Observation of a symmetry-protected topological phase in external magnetic fields
论文作者
论文摘要
拓扑阶段极大地改善了我们对现代物质阶段概念的理解，这些阶段超出了对称性破坏的范式，而不是由局部顺序参数描述。取而代之的是，拓扑阶段的表征需要强大的拓扑不变性，而测量这些全球量为实验带来了出色的挑战，尤其是在相互作用的系统中。在这里，我们报告了与相互作用的核自旋对对称性保护拓扑相的真实空间观察，并探测了两个拓扑上不同阶段之间的相互作用引起的过渡，这两个阶段都是由从对外部磁场的动力学响应中获得的多体Chern数量分类的。 Chern编号的结果值（$ \ bar {\ Mathcal {C} H} = 1.958 \ pm 0.070 $）演示了强大的基态退化，并且还确定了非平凡边缘状态的数量。我们的发现能够通过逐渐降低引入的外部场的强度来直接表征量子多体态的拓扑特征。
Topological phases have greatly improved our understanding of modern conception of phases of matter that go beyond the paradigm of symmetry breaking and are not described by local order parameters. Instead, characterization of topological phases requires the robust topological invariants, whereas measuring these global quantities presents an outstanding challenge for experiments, especially in interacting systems. Here we report the real-space observation of a symmetry-protected topological phase with interacting nuclear spins, and probe the interaction-induced transition between two topologically distinct phases, both of which are classified by many-body Chern numbers obtained from the dynamical response to the external magnetic fields. The resulting value of Chern number ($\bar{\mathcal{C}h} = 1.958 \pm 0.070$) demonstrates the robust ground state degeneracy, and also determines the number of nontrivial edge states. Our findings enable direct characterization of topological features of quantum many-body states through gradually decreasing the strength of the introduced external fields.
