Motivated by recent experimental advances in creating polar molecular gases in the laboratory, we theoretically investigate the many-body effects of two-dimensional (2D) dipolar systems with the anisotropic and $1/r^3$ dipole-dipole interactions. We calculate collective modes of 2D dipolar systems and also consider spatially separated bilayer and multilayer superlattice dipolar systems. We obtain the characteristic features of collective modes in quantum dipolar gases. We quantitatively compare the modes of these dipolar systems with the modes of the extensively studied usual two-dimensional electron systems, where the interparticle interaction is Coulombic.

• Received 22 September 2010

DOI:https://doi.org/10.1103/PhysRevB.82.235126