Precise determination of the Casimir force and first realization of a "Casimir less" experiment

We present improved Casimir effect measurements. The attractive force between a metallized sphere and the coated plate of a Si microelectromechanical oscillator is measured with unparalleled precision. The same setup, but in a dynamic scheme, yields a determination of the Casimir pressure between two infinite plates. Since the Casimir force is the dominant interaction in the 0.1-1 pm range under these experimental conditions, it acts as a background in the search for new forces in the submicrometer range. We report our progress in the realization of an experiment where the effect of the Casimir force is minimized (a "Casimir-less" configuration). This is achieved by measuring the difference in the force between the sphere and two metallic layers with different effective density, but the same Casimir contribution. These results are expected to strengthen the constraints imposed in hypothetical corrections to Newtonian gravitation.