Condensed Matter Seminar Series

The Casimir Force and Activated Escape in Micromechanical Systems

Ho Bun Chan

University of Florida Gainesville

Tuesday June 19,  11:30 am,  Room 298,  Physics Building

Abstract:  As micro and nanomechanical structures continue to shrink in size, fluctuation effects become increasingly important in their operation. The Casimir force, for example, originates from the zero-point quantum fluctuations of the electromagnetic field and the boundary conditions imposed by conducting surfaces. We demonstrated the Casimir effect using a micromechanical torsional oscillator. Ongoing efforts aim at measuring the nontrivial boundary dependence of the Casimir force. I will also describe other phenomena that arise from the interplay between fluctuations and nonlinearity. Under strong periodic drive, a nonlinear micromechanical oscillator develops bistability. Fluctuations induce switching between the coexisting dynamical states. We observed a wide range of generic phenomena, including universal scaling of the activation barrier near bifurcation points and the occurrence of kinetic phase transition at comparable state occupations.