Crossover between quantum and thermal regimes of free-standing nanostructures

Mesomechanical systems offer the possibility to observe and control certain quantum effects. Here we develop a phonon description of transverse motion of a mesoscopic beam with fixed endpoints. We obtain expressions for the fundamental frequencies and quantum fluctuation amplitudes of these structures when subjected to longitudinal compression. We show how the frequencies and fluctuation amplitudes scale with physical dimensions and give estimates for the crossover temperatures which characterize the transition between quantum and thermal regimes. (C) 2002 Elsevier Science B.V. All rights reserved.