Local and nonlocal Purcell factor control of an emitter in graphene under the modulation of a static magnetic field

Abstract

Spontaneous emission control of emitters holds great promise for applications in photonics and quantum optics. As a definition of the spontaneous emission lifetime of an atom or molecule, the Purcell factor of an emitter coupled with graphene controlled by a static magnetic field was studied. The results show that the Purcell factor can be effectively enhanced by applying an external magnetic field to graphene at low terahertz frequency. By analyzing the dispersion relations of graphene and the Purcell factor of an emitter nearby it, we find that the emitter-graphene interactions are most influenced by nonlocal effects at the low frequency, especially at a short emitter-graphene distance. The coupling between the emitter and the magnetic biased graphene becomes stronger under nonlocal effects, leading to a strong enhancement of the emission of the emitter. More specifically, the nonlocal Purcell factor can increase by orders of magnitude when the applied magnetic field is 10 T compared to the local model at a very short distance. The bias of the applied magnetic field extends a new path for the realization of Purcell factor modulation based on graphene-emitter interaction, and it may provide a promising application value for the design of the photo-magnetic-based quantum devices.