  A quantum-dot thermal transistor consisting of three Coulomb-coupled quantum
dots coupled to respective electronic reservoirs by tunnel contacts is
established. The heat flows through the collector and emitter can be controlled
by the temperature of the base. It is found that a small change in the base
heat flow can induce a large heat flow change in the collector and emitter. The
huge amplification factor can be obtained by optimizing the Coulomb interaction
between the collector and the emitter or by decreasing the energy-dependent
tunneling rate at the base. The proposed quantum-dot thermal transistor may
open up potential applications in low-temperature solid-state thermal circuits
at the nanoscale.
