  Quantum tunneling between two potential wells in a magnetic field can be
strongly increased when the potential barrier varies in the direction
perpendicular to the line connecting the two wells and remains constant along
this line. A periodic structure of the wave function is formed in the direction
joining the wells. The resulting motion can be coherent like motion in a
conventional narrow band periodic structure. A particle penetrates the barrier
over a long distance which strongly contrasts to WKB-like tunneling. The whole
problem is stationary. The coherent process can be influenced by dissipation.
