Cylindrical surface plasmon mode coupling as a three-dimensional Kaluza-   Klein theory
  Cylindrical surface plasmon (CSP) mode coupling in a nanowire or a nanochannel is described in terms of three-dimensional Kaluza-Klein theory in which the compactified third dimension is considered to be the angular coordinate of the metal cylinder. Higher (n>0) CSP modes are shown to posses a quantized effective charge proportional to their angular momentum n. In a nanowire these slow moving charges exhibit strong long-range interaction via fast massless CSPs with zero angular momentum (n=0). Such a mode-coupling theory may be used in description of nonlinear optics of cylindrical nanowires and nanochannels (for example, in single-photon tunneling effect), and may be further extended to describe interaction of electrons with nonzero angular momenta in thin gold wires and carbon nanotubes 
Igor I. Smolyaninov