Directional dipole radiations and long-range quantum entanglement mediated by hyperbolic metasurfaces.

In the vicinity of two-dimensional structures, the excitation of deep subwavelength polaritonic modes can be realized owing to the presence of free-carrier motion. Here we consider the launching of surface plasmonics in hyperbolic metasurfaces and theoretically demonstrate that the radiation energy of quantum emitter channels along specific directions was determined by the conductivity tensor of the surface. While the propagating length of the suface plasmon field supported by isotropic surfaces is normally limited on the scale of subwavelength to several vacuum wavelengths, it may be largely amplified when hyperbolic metasurfaces have been applied. Based on these exciting properties, prominent super- and subradiant behaviors between two distant quantum emitters are observed by engineering the anisotropy of the metasurfaces. Further investigations show that the directional collective interactions supported by the metasurfaces enable the generation of quantum entanglement over macroscopic dipole separations, with large values of concurrence, and allow remarkable revivals from sudden death. Our proposal can easily be extended to systems that include multiple quantum emitters interacting through hyperbolic metasurfaces and thus may have potential applications in on-chip science that aims at quantum information processing and quantum networks.