Nonequilibrium Fluctuations and Decoherence in Nanomechanical Devices   Coupled to the Tunnel Junction
  We analyze the dynamics of a nanomechanical oscillator coupled to an electrical tunnel junction with an arbitrary voltage applied to the junction and arbitrary temperature of electrons in leads. We obtain the explicit expressions for the fluctuations of oscillator position, its damping/decoherence rate, and the current through the structure. It is shown that quantum heating of the oscillator results in nonlinearity of the current-voltage characteristics. The effects of mechanical vacuum fluctuations are also discussed. 
Anatoly Yu. Smirnov, Lev G. Mourokh and Norman J.M. Horing