Polariton Heat Transport in Polar Dielectric Materials

Based on the Boltzmann transport equation and considering the simultaneous dynamics of polaritons and phonons, we derive analytical formulas for the polariton thermal conductivity and thermal conductance of nanofilms and nanowires supporting the propagation of surface polaritons along their surfaces. We show that the thermal conductance of ballistic polaritons propagating along a nanofilm and nanowire is independent of the material properties and is, respectively, given by \(12z(3)k_B^3T^2/ch^2\) and \(\pi ^2k_B^2 T/3h\) , where \(k_B\) and h are the Boltzmann and Planck constants, while c is the light speed in vacuum, T the temperature, and \(z(3)\) the Riemann zeta function. The huge propagation length of these energy carriers establishes that this quantization holds not only for temperatures much smaller than 1 K, as is the case of electrons and phonons, but also for those comparable to room temperature, which can significantly facilitate their observation and application to enhance the heat dissipation along nanostructures. Furthermore, we demonstrate that the deviation of the temperature profile from its linear behavior represents the signature of polariton–phonon coupling in nanofilms and nanowires.