Dipole induced transparency in drop-filter cavity-waveguide systems.

We show that a waveguide that is normally opaque due to interaction with a drop-filter cavity can be made transparent when the drop filter is also coupled to a dipole, even when the vacuum Rabi frequency of the dipole is much less than the cavity decay rate. The condition for transparency is simply achieving large Purcell factors. We describe how this effect can be useful for designing quantum repeaters for long distance quantum communication.