Solitonic transmission of Bose-Einstein matter waves

We consider a continuous atom laser propagating through a wave guide with a constriction. Two different types of transmitted stationary flow coexist. The first one coincides, at low incident current, with the non-interacting flow. As the incident flux increases, the repulsive interactions decrease the corresponding transmission coefficient. The second type only occurs for sufficiently large incident currents and has a solitonic structure. Remarkably, for any chemical potential there always exists a value of the incident flux at which the solitonic flow is perfectly transmitted.