Universality and diversity in a phonon-transmission histogram of isotope-disordered carbon nanotubes.

Universal fluctuations in phonon transmission and other features of phonon-transmission histograms are investigated by performing numerical simulations of coherent-phonon transport in isotope-disordered carbon nanotubes. Interestingly, the phonon-transmission fluctuation in the diffusive regime is universal, irrespective of the average phonon transmission, the tube chirality, and the concentrations, and masses of isotopes. We also find that the histogram, which has a Gaussian distribution in the diffusive regime, has a log-normal distribution in the localization regime.