论文标题
使用投影$ PT $对称性切换无旋转和跨的拓扑阶段
Switching spinless and spinful topological phases with projective $PT$ symmetry
论文作者
论文摘要
所有物理系统的基本二分法分类是根据它们是无纺丝还是稀疏的。这对于研究对称性保护拓扑阶段的研究尤其重要，因为这两个类别具有不同的对称代数。作为一个突出的例子，时空反转对称$ pt $满足$（pt）^2 = \ pm 1 $对于无旋转/跨的系统，每个类都具有独特的拓扑阶段。在这里，我们揭示了通过$ \ mathbb {z} _2 $投影表示的可能性切换两个基本类的可能性。对于$ pt $对称性，这发生在$ p $逆转恢复原始$ \ mathbb {z} _2 $量规连接所需的量规变换时。结果，我们可以实现最初在无旋转系统中跨系统的拓扑阶段，反之亦然。我们通过多种混凝土模型明确说明了所主张的机制，例如Kramers变性带和KRAMERS MARIAMANA边界模式在无旋转系统中，以及跨系统中的真实拓扑阶段。讨论了这些模型可能的实验实现。我们的工作打破了对拓扑阶段的基本局限性，并为实现以前不可能的系统中有趣的拓扑阶段开辟了前所未有的可能性。
A fundamental dichotomous classification for all physical systems is according to whether they are spinless or spinful. This is especially crucial for the study of symmetry-protected topological phases, as the two classes have distinct symmetry algebra. As a prominent example, the spacetime inversion symmetry $PT$ satisfies $(PT)^2=\pm 1$ for spinless/spinful systems, and each class features unique topological phases. Here, we reveal a possibility to switch the two fundamental classes via $\mathbb{Z}_2$ projective representations. For $PT$ symmetry, this occurs when $P$ inverses the gauge transformation needed to recover the original $\mathbb{Z}_2$ gauge connections under $P$. As a result, we can achieve topological phases originally unique for spinful systems in a spinless system, and vice versa. We explicitly demonstrate the claimed mechanism with several concrete models, such as Kramers degenerate bands and Kramers Majorana boundary modes in spinless systems, and real topological phases in spinful systems. Possible experimental realization of these models is discussed. Our work breaks a fundamental limitation on topological phases and opens an unprecedented possibility to realize intriguing topological phases in previously impossible systems.
