# Classical and quantum dispersion-free coherent propagation by tailoring multi-modal coupling

## TL;DR

This paper presents a method to control chromatic dispersion in waveguides and fibers by tailoring mode coupling through weak scattering, enabling long-distance coherent classical and quantum signal transmission.

## Contribution

It introduces an analytic approach based on quantum control techniques to tailor mode coupling and dispersion, including corrections for non-unitary effects in realistic conditions.

## Key findings

- Achieves dispersion control at any order in waveguides and fibers.
- Provides an analytic solution for ideal scattering conditions.
- Extends methodology to account for weak back-scattering effects.

## Abstract

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 non-unitary effects in the presence of weak back-scattering. In practice, it requires scatterers able to couple different modes and carefully designed dispersion laws giving a null average quadratic dispersion in the spectral vicinity of the operational frequency.