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 the additional advantage of a strongly anharmonic Landau level spectrum so that a two-level system may be readily explored. We have recently demonstrated graphene cyclotron transitions with quality factor Q~500 at a field of 8 T. Incorporated into cavities with either thin metal or dielectric mirrors, we estimate that cooperativities C~100 and reduced coupling strengths \eta~g/\omega~0.2 can be reached using graphene in an infrared cavity. 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)