  An exciton beam splitter is designed and computationally implemented,
offering the prospect of excitonic interferometry. Exciton interaction between
propagation conduits is modeled using a coupling parameter that varies with
position. In practice, this variation can be realized by a change in the
distance separating conduits as would occur if they crossed at oblique angles.
Two such excitonic beam splitters can be combined to comprise an excitonic
analog to a Mach-Zehnder interferometer, allowing the relative phase shift
between two signals to be used to tailor the output populations on each
channel. In contrast to optical splitters, an excitonic signal can be
coherently split among more than two channels. These ideas are computationally
demonstrated within an idealized setting in which each site is idealized as a
two-level system. Physical implementations include molecular and coupled cavity
settings as well as combinations of these. This adds to the developing
inventory of excitonic analogs to optical elements.
