  Thermal transistor is an efficient heat control device which can act as a
heat switch as well as a heat modulator. In this paper, we study systematically
one-dimensional and two-dimensional thermal transistors. In particular, we show
how to improve significantly the efficiency of the one-dimensional thermal
transistor. The study is also extended to the design of two-dimensional thermal
transistor by coupling different anharmonic lattices such as the
Frenkel-Kontorova and the Fermi-Pasta-Ulam lattices. Analogy between anharmonic
lattices and single-walled carbon nanotube is drawn and possible experimental
realization with multi-walled nanotube is suggested.
