  Following the nonequilibrium Green's function formalism we study the thermal
transport in a composite chain subject to a time-dependent perturbation. The
system is formed by two finite linear asymmetric harmonic chains subject to an
on-site potential connected together by a time-modulated coupling. The ends of
the chains are coupled to two phononic reservoirs at different temperatures. We
present the relevant equations used to calculate the heat current along each
segment. We find that the system presents different transport regimes according
the driving frequency and temperature gradients. One of the regimes corresponds
to a heat pump against thermal gradient, thus a characterization of the cooling
performance of the device is presented.
