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P.G. Kevrekidis, D.E. Pelinovsky, and D.Y.Tyugin

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Nonlinear dynamics in PT-symmetric lattices

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Journal of Physics A: Mathematical Theoretical 46, 365201 (17 pages) (2013)

**Abstract:**

We consider nonlinear dynamics in a finite parity-time-symmetric chain
of the discrete nonlinear Schrodinger (dNLS) type. For arbitrary values of the gain and loss parameter,
we prove that the solutions of the dNLS equation do not blow up in a finite time but nevertheless,
there exist trajectories starting with large initial data that grow
exponentially fast for larger times with a rate that is rigorously
identified. In the range of the gain and loss parameter, where
the zero equilibrium state is neutrally stable, we prove that
the trajectories starting with small initial data remain bounded for all times.
Numerical computations illustrate these analytical results for dimers and quadrimers.

**Keywords:**

PT-symmetry, discrete Schrodinger equation, nonlinear dynamics, global existence, Lyapuov stability