Photon transport in low-dimensional nanostructures

At low temperatures when the phonon modes are effectively frozen, photon transport is the dominating mechanism of thermal relaxation in metallic systems [1]. Starting from a microscopic many-body Hamiltonian using the equation-of-motion technique for nonequilibrium Green's functions, we study the energy transport by photons in nanostructures. We obtain a formally exact expression for the energy current between a metallic island and a one-dimensional electromagnetic field supported by a parallel strip transmission line. From this expression we derive the quantized thermal conductance as well as show how the electron shot noise affects the photon transport. Frequency-dependent current noise essentially determines the transport process, thus providing a close connection between electron transport and photon transport [2]. \newline \newline [1] M. Meschke, W. Guichart and J. P. Pekola, Nature {\bf 444}, 187 (2006). \newline [2] T. Ojanen and T. T. Heikkil\"a, to be published.