  We investigate the propagation of electron wavepackets in single-walled
carbon nanotubes via a Lindblad-based density-matrix approach that enables us
to account for both dissipation and decoherence effects induced by various
phonon modes. We show that, while in semiconducting nanotubes the wavepacket
experiences the typical dispersion of conventional materials, in metallic
nanotubes its shape remains essentially unaltered, even in the presence of the
electron-phonon coupling, up to micron distances at room temperature.
