  We show how to create maximal entanglement between spectrally distinct
solid-state emitters embedded in a waveguide interferometer. By revealing the
rich underlying structure of multi-photon scattering in emitters, we show that
a two-photon input state can generate deterministic maximal entanglement even
for emitters with significantly different transition energies and line-widths.
The optimal frequency of the input is determined by two competing processes:
which-path erasure and interaction strength. We find that smaller spectral
overlap can be overcome with higher photon numbers, and quasi-monochromatic
photons are optimal for entanglement generation. Our work provides a new
methodology for solid-state entanglement generation, where the requirement for
perfectly matched emitters can be relaxed in favour of optical state
optimisation.
