Easy Vortex Motion in an Artificial Channel of $YBa_2Cu_3O_{7-δ}$ Superconducting Films

Quasi-Josephson effect produced by a coherent vortex motion in the horizontal part of the laser-performedΠ-shaped channel of a $YBa_2Cu_3O_{7-δ}$ superconducting bridge was investigated by means of electric transport measurements. We observed that in our structures, in a limited range of temperatures and bias currents, the vortices were confined in the channel only and moved coherently with the velocity of $3×10^4$ m/s. The corresponding current-voltage characteristics of the bridge exhibited Josephson-like voltage steps with the amplitude dependent on temperature, but independent of the bias current.