Instruct: Identify the main and secondary category of Arxiv papers based on the titles and abstracts
Query: Ultrastrong coupling of the cyclotron transition of a two-dimensional
  electron gas to a THz metamaterial   Artificial cavity photon resonators with ultrastrong light-matter
interactions are attracting interest both in semiconductor and superconducting
systems, due to the possibility of manipulating the cavity quantum
electrodynamic ground state with controllable physical properties. We report
here experiments showing ultrastrong light-matter coupling in a terahertz
metamaterial where the cyclotron transition of a high mobility two-dimensional
electron gas is coupled to the photonic modes of an array of electronic
split-ring resonators.
  We observe a normalized coupling ratio $\frac{\Omega}{\omega_c}=0.58$ between
the vacuum Rabi frequency $\Omega$ and the cyclotron frequency $\omega_c$. Our
system appears to be scalable in frequency and could be brought to the
microwave spectral range with the potential of strongly controlling the
magnetotransport properties of a high-mobility 2DEG.

16
The categories of this paper are: stat
11
The categories of this paper are: hep-lat
1
The categories of this paper are: cs
37
The categories of this paper are: supr-con
18
The categories of this paper are: econ
6
The categories of this paper are: astro-ph
27
The categories of this paper are: comp-gas
33
The categories of this paper are: plasm-ph
22
The categories of this paper are: chao-dyn
9
The categories of this paper are: nlin
0
The categories of this paper are: hep-ph
3
The categories of this paper are: physics
15
The categories of this paper are: nucl-ex
29
The categories of this paper are: funct-an
14
The categories of this paper are: math-ph
23
The categories of this paper are: solv-int