Abstract

A Dirac Point (DP) is the intersection of two electronic bands with a conical shape in a single point. They have attracted broad attention for several years due to their extraordinary properties and implications in Topology. Having such entities in non-Hermitian systems can open the door to new phenomena and applications. However, the inclusion of losses in a Hermitian system in the form of absorption or the opening of a radiation channel transforms the DP into a pair of Exceptional points (EPs) linked by a Fermi arc [1]. Yet, in the case of radiation losses, the EPs can be affected by the presence of Bound states in the continuum (BICs). Systems with a BIC in each band can be tuned so that the two BIC intersects at the Fermi arc. The result is a lossless point where the two bands intersect with a conical shape, i.e., a DP. However, this DP is surrounded by non-hermitian states with radiation losses. This new topological entity is therefore a Dirac point embedded in the continuum (DEC) [2,3]. DECs combine the topological properties of Dirac points with the extraordinary resonance features of BICs, potentially unlocking a plethora of unexplored phenomena and new applications.

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