  We introduce a novel class of higher-order, three-mode states called
K-dimensional trio coherent states. We study their mathematical properties and
prove that they form a complete set in a truncated Fock space. We also study
their physical content by explicitly showing that they exhibit nonclassical
features such as oscillatory number distribution, sub-poissonian statistics,
Cauchy-Schwarz inequality violation and phase-space quantum interferences.
Finally, we propose an experimental scheme to realize the state with K=2 in the
quantized vibronic motion of a trapped ion.
