  We consider an array of the meta-atom consisting of two cut-wires and a
split-ring resonator interacting with an electromagnetic field with two
polarization components. We prove that such metamaterial system can be taken as
a classical analogue of an atomic medium with a double- $\Lambda$-type
four-level configuration coupled with four laser fields, exhibits an effect of
plasmon induced transparency (PIT), and displays a similar behavior of atomic
four-wave mixing (FWM). We demonstrate that when nonlinear varactors are
mounted onto the gaps of the split-ring resonators the system can acquire giant
second- and third-order Kerr nonlinearities via the PIT and a
longwave-shortwave interaction. We also demonstrate that the system supports
high-dimensional vector plasmonic dromions [i.e. (2+1)-dimensional plasmonic
solitons with two polarization components, each of which has a coupling between
a longwave and a shortwave], which have very low generation power and are
robust during propagation. Our work gives not only a plasmonic analogue of the
FWM in coherent atomic systems but also provides the possibility for obtaining
new type of nonlinear polaritons in plasmonic metamaterials.
