Coherent- coupling of metamaterial resonators with hydrogen-like acceptor impurities in Si

Dr. Fanqi Meng1, Dr. FeiFan Han2, Mr. Ulrich Kentsch3, Dr. Alexej Pashkin3, Dr. Ciaran Fowley3, Dr. Lars Rebohle3, Prof. Safumi Suzuki2, Prof. Masahiro Asada2, Dr. Mark Thomson1, Prof. Hartmut Roskos1
1Goethe-Universit├Ąt Frankfurt, Frankfurt, Germany. 2Tokyo Institute of Technology, Tokyo, Japan. 3Helmholtz-Zentrum Dresden-Rossendorf, Dresden, Germany


In the past decades, light-matter interaction in photonic cavities has provided a unique testbed for the investigation of fundamental quantum physics. The coupling of cavity photons and excitations of the material leads to the formation of polariton quasi-particles. These newly dressed states reveal themselves by Rabi-split transitions in the absorption spectra when the light-matter interaction is in the strong coupling regime. In another context, shallow dopants are an essential ingredient of all semiconductor devices. At low temperatures, the energy states of dopants can be modeled in a hydrogen-like fashion. Because of the dielectric environment and the interaction with the host material, the electron transition dipole moments can be several orders of magnitude larger than those of free atoms.  Here, we demonstrate a strong interaction between an electron transition of boron dopants in Si and a metamaterial cavity. We employed multi-energy ion implantation to generate a thin layer of boron dopants with doping densities of 2x1017 cm-3 and 4x1016 cm-3. The measured Rabi splittings for both samples are 400 GHz and 200 GHz. This is consistent with the pre­dic­tion of cavity quantum electro­dynamics that the coupling strength should be proportional to the square root of the number of particles involved in the coupling. Based on those values, our coupled system lies at the boundary between the weak coupling regime and the electromagnetically induced transparency (EIT) regime.