No abstract

We study the transient heat generation in a quantum dot system driven by a step-like or a squareshaped pulse bias. We find that a periodically oscillating heat generation arises after adding the sudden bias. One particularly surprising result is that there exists a heat absorption from the zero-temperature phonon subsystem. Thus the phonon population in non-equilibrium can be less than that of the equilibrium electron-phonon system. In addition, we also ascertain the optimal conditions for the operation of a quantum dot with the minimum heat generation.

We theoretically study the time-averaged heat generation in a quantum dot over one period of an ac bias. By tuning the frequency x of the ac bias, it is shown that for the definite x ¼ x q =k, where x q is the frequency of the phonon mode and k is an integer number, there appears an sharp resonant energy transfer from the electron subsystem to the phonon subsystem. Such a phenomenon can be interpreted as a consequence of the indirect coupling between the electric oscillation and the nanomechanical vibration via the tunnelling electrons. Moreover, this feature is susceptive to the parameters of transport, by change of which the heat generation will be limited or enhanced as we desire. V C 2012 American Institute of Physics. [http://dx.