论文标题
浮点高阶拓扑阶段在动量空间中
Floquet higher-order topological phases in momentum space
论文作者
论文摘要
高阶拓扑阶段（HOTP）的特征在于系统的拐角处或铰链处。在这项工作中，我们在时间周期驱动的系统中揭示了热空间的动量空间对应物，该系统在量子双球转子的二维扩展中进行了证明。发现的Floquet Hotps受手性对称性的保护，其特征是一对拓扑不变的，可以随着踢脚强度的提高而任意较大的整数值。这些拓扑数也可以通过波数据包的手性动力学来测量。在开放的边界条件下，系统中出现了零和$π$准子的浮点角模式，并与同一准烯酚的Dellocalized Bulk状态共存，形成连续体的二阶Floquet Floquet拓扑结合状态。这些角模式的数量是根据散装对应关系的关系进一步计算的。因此，我们的发现将研究的热点扩展到了动量空间的晶格，并进一步揭示了Floquet驱动系统中连续体中热点和拐角处结合状态的丰富性。
Higher-order topological phases (HOTPs) are characterized by symmetry-protected bound states at the corners or hinges of the system. In this work, we reveal a momentum-space counterpart of HOTPs in time-periodic driven systems, which are demonstrated in a two-dimensional extension of the quantum double-kicked rotor. The found Floquet HOTPs are protected by chiral symmetry and characterized by a pair of topological invariants, which could take arbitrarily large integer values with the increase of kicking strengths. These topological numbers can also be measured from the chiral dynamics of wave packets. Under open boundary conditions, multiple quartets Floquet corner modes with zero and $π$ quasienergies emerge in the system and coexist with delocalized bulk states at the same quasienergies, forming second-order Floquet topological bound states in continuum. The numbers of these corner modes are further counted by the bulk topological invariants according to the relation of bulk-corner correspondence. Our findings thus extend the study HOTPs to momentum-space lattices, and further uncover the richness of HOTPs and corner-localized bound states in continuum in Floquet driven systems.
