Giuseppe Castaldi, Silvio Savoia, Vincenzo Galdi, Andrea Alu’, Nader Engheta

We extend the transformation-optics paradigm to a complex spatial coordinate domain, in order to deal with electromagnetic metamaterials characterized by balanced loss and gain, giving special emphasis to parity-time (PT) symmetry metamaterials. We apply this general theory to complex-source-point radiation and unidirectional invisibility, illustrating the capability and potentials of our approach in terms of systematic design, analytical modeling and physical insights into complex-coordinate wave-objects and resonant states.

http://arxiv.org/abs/1210.7629

Optics (physics.optics)

W.D. Heiss

A short resume is given about the nature of exceptional points (EPs) followed by discussions about their ubiquitous occurrence in a great variety of physical problems. EPs feature in classical as well as in quantum mechanical problems. They are associated with symmetry breaking for ${\cal PT}$-symmetric Hamiltonians, where a great number of experiments have been performed in particular in optics, and to an increasing extent in atomic and molecular physics. EPs are involved in quantum phase transition and quantum chaos, they produce dramatic effects in multichannel scattering, specific time dependence and more. In nuclear physics they are associated with instabilities and continuum problems. Being spectral singularities they also affect approximation schemes.

http://arxiv.org/abs/1210.7536

Quantum Physics (quant-ph); Mathematical Physics (math-ph)