Matter wave propagation above a step potential within the   cubic-nonlinear Schr\"odinger equation
  We analyze the matter wave transmission above a step potential within the framework of the cubic-nonlinear Schr\"odinger equation. We present a comprehensive analysis of the corresponding stationary problem based on an exact second-order nonlinear differential equation for the probability density. The exact solution of the problem in terms of the Jacobi elliptic sn-function is presented and analyzed. Qualitatively distinct types of wave propagation picture are classified depending on the input parameters of the system. Analyzing the 2D space of involved dimensionless parameters, the nonlinearity and the reflecting potential's height/depth given in the units of the chemical potential, we show that the region of the parameters that does not sustain restricted solutions is given by a closed curve consisting of a segment of an elliptic curve and two line intervals. We show that there exists a specific singular point, belonging to the elliptic curve, which causes a jump from one evolution scenario to another one. The position of this point is determined and the peculiarities of the evolution scenarios (oscillatory, non-oscillatory and diverging) for all the allowed regions of involved parameters are described and analyzed in detail. 
H.A. Ishkhanyan, A.M. Manukyan, and A.M. Ishkhanyan
cond-mat.quant-gas