  We investigate the influence of static disorder and thermal excitations on
excitonic energy transport in the light-harvesting apparatus of photosynthetic
systems by solving the Schr\"{o}dinger equation and taking into account the
coherent hoppings of excitons, the rates of exciton creation and annihilation
in antennas and reaction centers, and the coupling to thermally excited
phonons. The antennas and reaction centers are modeled, respectively, as the
sources and drains which provide the channels for creation and annihilation of
excitons. Phonon modes below a maximum frequency are coupled to the excitons
that are continuously created in the antennas and depleted in the reaction
centers, and the phonon population in these modes obeys the Bose-Einstein
distribution at a given temperature. It is found that the energy transport is
not only robust against the static disorder and the thermal noise, but it can
also be enhanced by increasing the randomness and temperature in most parameter
regimes. Relevance of our work to the highly efficient energy transport in
photosynthetic systems is discussed.
