PT-symmetry in optics
a Moscow Institute of Physics and Technology (State University), Institutskii per. 9, Dolgoprudnyi, Moscow Region, 141700, Russian Federation
b Dukhov Research Institute of Automatics, ul. Sushchevskaya 22, Moscow, 119017, Russian Federation
c Institute for Theoretical and Applied Electrodynamics, Russian Academy of Sciences, ul. Izhorskaya 13/19, Moscow, 127412, Russian Federation
d Department of Physics, Queens College of the City University of New York, Flushing, New York, USA
Quantum-mechanical and optical pseudo-Hermitian systems are reviewed with emphasis on PT-symmetric systems important for optics and electrodynamics. One of the most interesting and much discussed consequences of PT-symmetry is a phase transition with the breaking of the symmetry of the system's eigenstates. We show in the review that, although this phase transition is difficult to realize experimentally, a similar transition can be observed in quasi-PT-symmetric systems. Other effects predicted for PT-symmetric systems are not specific for these systems and can be observed in ordinary fully-passive systems.