Superradiance transition in graphene

• We determine the conditions for appearance of a superradiance transition (ST) in graphene.
• ST in a single-layer graphene is related to occurrence of an exceptional points (EP) and to overlapping of two resonances.
• In the undoped graphene case the superradiance transition occurs at the EP.
• The maximal efficiency of the electron transfer is related to the superradiance state.

We study theoretically the conditions required for the appearance of a superradiance transition in graphene. The electron properties of graphene are described in the single pzpz-orbital tight-binding approximation, corresponding to the two interacting sub-lattices. The corresponding model is reduced to the effective two-level pseudo-spin 1/2 system. For each sub-lattice we introduce the electron transfer rate of escape into a continuum. We demonstrate that, under some conditions, the superradiance occurs, and it corresponds to the maximal quantum coherent escape to the continuum.