Experimental model of topological defects in Minkowski space-time based on disordered ferrofluid: magnetic monopoles, cosmic strings and the space-time cloak.

In the presence of an external magnetic field, cobalt nanoparticle-based ferrofluid forms a self-assembled hyperbolic metamaterial. The wave equation, which describes propagation of extraordinary light inside the ferrofluid, exhibits 2+1 dimensional Lorentz symmetry. The role of time in the corresponding effective three-dimensional Minkowski space-time is played by the spatial coordinate directed along the periodic nanoparticle chains aligned by the magnetic field. Here, we present a microscopic study of point, linear, planar and volume defects of the nanoparticle chain structure and demonstrate that they may exhibit strong similarities with such Minkowski space-time defects as magnetic monopoles, cosmic strings and the recently proposed space-time cloaks. Experimental observations of such defects are described.

Lattice models of nontrivial "optical spaces" based on metamaterial waveguides.

Metamaterials are being used to model various exotic "optical spaces" for such applications as novel lenses and cloaking. While most efforts are directed toward the engineering of continuously changing dielectric permittivity and magnetic permeability tensors, an alternative approach may be based on lattices of metamaterial waveguides. Here we demonstrate the power of the latter technique by presenting metamaterial lattice models of various four-dimensional spaces.