Cavity quantum electrodynamics with cyclotron resonance transitions in graphene

Cyclotron resonance transitions between highly - degenerate Landau levels are good candidates to achieve the ultrastrong coupling regime in cavity QED, as shown recently for GaAs quantum wells [1]. Graphene provides a similarly ideal platform, with additional advantage of a strongly anharmonic Landau level spectrum so that a two-level system can be readily explored. We have recently demonstrated graphene cyclotron transitions with Q ~ 200 at 8T magnetic field. Incorporated into cavities with either thin metal or dielectric mirrors, we estimate that cooperativities of C ~ 100 and reduced coupling strengths g/ω ~ 0.2 can be reached using graphene in an infrared cavity. Coupling strength can be increased by improving the quality factor and reducing the mode volume of the designed cavities which leads to stronger confinement of light. We will present initial results of measurements on such graphene cavity QED devices and outline prospects for reaching higher coupling strengths.
[1] Zhang et al, N. Phys 12, 1005 (2016)