  The magneto-optical effect breaks time-reversal symmetry, a unique property
that makes it indispensable in nonreciprocal optics and topological photonics.
Unfortunately, all natural materials have a rather weak magneto-optical
response in the optical frequency range, posing a significant challenge to the
practical application of many emerging device concepts. Here we theoretically
propose a composite material system that exhibits an intrinsic magneto-optical
response orders of magnitude stronger than most magneto-optical materials used
today. This is achieved by tailoring the resonant interplay between the quantum
electrodynamics of electronic transitions in two-level systems and the
classical electromagnetic response of local plasmon resonance.
