Classical and quantum dispersion-free coherent propagation by tailoring multimodal coupling

It is shown that tailored breaking of the translational symmetry through weak scattering in waveguides and optical fibers can control chromatic dispersions of the individual modes at any order; thereby, it overcomes the problem of coherent classical and quantum signal transmission at long distances. The methodology is based on previously developed quantum control techniques and gives an analytic solution in ideal scattering conditions; it has been also extended to incorporate and correct nonunitary effects in the presence of weak backscattering. In practice, it requires scatterers able to couple different modes and carefully designed dispersion laws giving a null average quadratic distortion in the spectral vicinity of the operational frequency.