论文标题
嵌入在连续体中的狄拉克点
Dirac Points Embedded in the Continuum
论文作者
论文摘要
Hermitian系统中的狄拉克点（DP）在拓扑现象中起着关键作用。因此，他们在非热系统中的存在是可取的，但是增加损失或增益将DPS转化为由费米弧（Fermi Arc）连接的异常点（EP），它们表现出有趣但不同的特性。当过渡到非炎症系统是由辐射通道的打开而导致的，该系统还可以支持连续体（BICS）中的结合状态，后者是出现在辐射状态内的非辐射谐振状态。从理论上讲，我们表明，两种BIC的同时进行带串联可以防止EPS和Fermi弧的形成，从而导致真正的Hermitian DPS，尽管如此，这些DP仍嵌入了辐射状态的连续体中。嵌入在连续体（DECS）中的狄拉克点是一个新的拓扑实体，它将与DPS相关的丰富物理学与非富米特系统中BIC的理想谐振特性相结合。
Dirac points (DP) in Hermitian systems play a key role in topological phenomena. Their existence in non-Hermitian systems is then desirable, but the addition of loss or gain transforms DPs into pairs of Exceptional Points (EPs) joined by a Fermi arc, which exhibit interesting but different properties. When the transition to a non-Hermitian system results from the opening of a radiation channel, the system can also support bound states in the continuum (BICs), which are non-radiative resonant states that appear within the band of radiation states. We theoretically show that simultaneous band-crossing of two BICs can prevent the formation of EPs and Fermi arcs, resulting in genuine Hermitian DPs, which are nonetheless embedded in the continuum of radiation states. Dirac points embedded in the continuum (DECs) are a new topological entity that combines the rich physics associated with DPs with the ideal resonant properties of BICs in non-Hermitian systems.
