  Quantum energy transfer in a chain of two-level (spin) units, connected at
its ends to two thermal reservoirs, is analyzed in two limits: (i) In the
off-resonance regime, when the characteristic subsystem excitation energy gaps
are larger than the reservoirs frequencies, or the baths temperatures are low.
(ii) In the resonance regime, when the chain excitation gaps match populated
bath modes. In the latter case the model is studied using a master equation
approach, showing that the dynamics is ballistic for the particular chain model
explored. In the former case we analytically study the system dynamics
utilizing the recently developed Energy-Transfer Born-Oppenheimer formalism
[Phys. Rev. E {\bf 83}, 051114 (2011)], demonstrating that energy transfers
across the chain in a superexchange (bridge assisted tunneling) mechanism, with
the energy current decreasing exponentially with distance. This behavior is
insensitive to the chain details. Since at low temperatures the excitation
spectrum of molecular systems can be truncated to resemble a spin chain model,
we argue that the superexchange behavior obtained here should be observed in
widespread systems satisfying the off-resonance condition.
