  Exciton-polaritons are mutually interacting quantum hybridizations of
confined photons and electronic excitations. Here we demonstrate a system of
optically guided, electrically polarized exciton-polaritons ('dipolaritons')
that displays up to 200-fold enhancement of the polariton-polariton interaction
strength compared to unpolarized polaritons. The magnitude of the dipolar
interaction enhancement can be turned on and off and be easily tuned over a
very wide range by varying the applied polarizing electric-field. The very
large interaction strengths and the very long propagation distances of these
fully-guided dipolaritons open up new opportunities for realizing complex
quantum circuitry and quantum simulators, as well as topological states based
on exciton-polaritons, for which the interactions between polaritons need to be
large and spatially or temporally controlled. The results also raise
fundamental questions on the origin of such large enhancements.
