We show that metamaterials can be used as a testing ground to investigate spontaneous symmetry breaking associated with non-Hermitian quantum systems. By exploring the interplay between near-field dipolar coupling and material absorption or gain, we demonstrate various spontaneous breaking processes of the \(\mathcal{PT}\)-symmetry for a series of effective Hamiltonians associated to the scattering matrix. By tuning the coupling parameter, coherent perfect absorption, laser action and gain-induced complete reflection (\(\pi\) reflector) by using an ultra-thin metamaterial can be obtained. Moreover, an ideal \(\mathcal{PT}\)-symmetry can be established effectively in a passive system by using metamaterials.

http://arxiv.org/abs/1210.2027
Optics (physics.optics); Mesoscale and Nanoscale Physics (cond-mat.mes-hall); Classical Physics (physics.class-ph)