Macroscopic quantum effects in nanomechanical systems

We investigate quantum effects in the mechanical properties of elastic beams on the nanoscale. Transverse quantum and thermal fluctuations and the nonlinear excitation energies are calculated for beams compressed in longitudinal direction. Near the Euler instability, the system is described by a one-dimensional Ginzburg-Landau model, where the order parameter is the amplitude of the buckling mode. We show that in single-wall carbon nanotubes with lengths of the order of or smaller than 100 nm, zero-point fluctuations are accessible, and discuss the possibility of observing macroscopic quantum coherence in nanobeams near the critical strain.