Spontaneous emission mediated by graphene/hexagonal boron nitride/graphene sandwich structure

Controlling the spontaneous emission of atoms or molecules is an interesting research topic in the field of quantum optics. Here we provide a perspective on modulating the interaction between two quantum emitters through a sandwich structure composed of graphene and hexagonal boron nitride (hBN). The dependence of interaction between quantum emitters on the thickness of hBN and chemical potential of graphene is investigated in detail. When the transition frequency of quantum emitter is located in the hyperbolic band of type I supported by hBN, the radiative state can be easily modulated by adjusting the chemical potential of graphene. So it is flexible to switch the interaction of quantum emitters from superradiant state to subradiant state by external electric field. When the transition frequency of quantum emitter is located in hyperbolic band of type II, the system can be always in the superradiant state. We predict the further research perspectives of spontaneous emission and superradiance with the help of metasurfaces based on two-dimensional materials.

COLLAPSES AND REVIVALS IN TWO-LEVEL ATOMS IN A SUPERPOSED STATE INTERACTING WITH A SINGLE MODE SUPERPOSED COHERENT RADIATION

Collapses and revivals phenomenon in system of a single two-level atom and two two-level atoms existing in some superposed states and interacting with a single mode superposed coherent radiation is studied. For superposed Dicke states |1/2, ±1/2> of a single two-level atom interacting with even or odd coherent state, only odd revivals occur. For two two-level atoms, it is found that the collapse and revival times for even and odd coherent states are equal to one half of the corresponding times for coherent state. For this system, Rabi oscillations occur with a main mean frequency and also some second harmonics are present, in general. However, if the two atoms are in the superradiant state, only the second harmonics with large amplitude are obtained. The appearance of weak double frequency revivals for superposed atomic and coherent states was studied and a condition for their disappearance is found.

THE NONEQUILIBRIUM DESCRIPTION OF SUPERRADIANT STATE ON THE BASIS OF EXACT EVOLUTION EQUATION

The non-equilibrium quantum statistical conditions of the superradiant decay are derived in the framework of the Bogolubov method for eliminating the Bose-operators. Two time scales are introduced in order to advance the concept of quasi-stationary states that makes it possible to use the main achievements of the equilibrium description. With the self-consistent field approximation and the small value of the coupling constant the conditions are shown to be in good agreement with the recent experiments on superradiance in mixed crystals carried out by the Dusseldorf group.