Surface roughness influence on parametric amplification of   nanoresonators in presence of thermomechanical and environmental noise
  We investigate the surface roughness influence on the gain from parametric amplification in nanoresonators in presence of thermomechanical and momentum exchange noise. The roughness is characterized by the rms amplitude w, the correlation length X, and the roughness exponent 0<H<1. It is found that the gain strongly increases with increasing roughening (decreasing H and/or increasing ratio w/ X) due to increment of capacitive coupling, which plays dominant role when the intrinsic quality factor Qin is comparable or lower than the quality factor Qgas due to gas collisions. However, for Qin>>Qgas, the influence of surface roughness on the gain strongly diminishes. 
G. Palasantzas physics.optics