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Day January 7, 2013

Topologically protected midgap states in complex photonic lattices

Henning Schomerus

One of the principal goals in the design of photonic crystals is the engineering of band gaps and defect states. Drawing on the concepts of band-structure topology, I here describe the formation of exponentially localized, topologically protected midgap states in photonic systems with spatially distributed gain and loss. When gain and loss are suitably arranged these states maintain their topological protection and then acquire a selectively tunable amplification rate. This finds applications in the beam dynamics along a photonic lattice and in the lasing of quasi-one-dimensional photonic crystals.

http://arxiv.org/abs/1301.0777
Optics (physics.optics); Mesoscale and Nanoscale Physics (cond-mat.mes-hall)

Non-Hermitian Oscillator and R-deformed Heisenberg Algebra

Rajkumar Roychoudhury, Barnana Roy, Partha Pratim Dube

A non-Hermitian generalized oscillator model, generally known as the Swanson model, has been studied in the framework of R-deformed Heisenberg algebra. The non-Hermitian Hamiltonian is diagonalized by generalized Bogoliubov transformation. A set of deformed creation annihilation operators is introduced whose algebra shows that the transformed Hamiltonian has conformal symmetry. The spectrum is obtained using algebraic technique. The superconformal structure of the system is also worked out in detail. An anomaly related to the spectrum of the Hermitian counterpart of the non-Hermitian Hamiltonian with generalized ladder operators is shown to occur and is discussed in position dependent mass scenario.

http://arxiv.org/abs/1301.0716
Mathematical Physics (math-ph); Quantum Physics (quant-ph)