A precision measurement of the Casimir force using metallic gold surfaces is reported. The force is measured between a large gold-coated sphere and flat plate using an atomic force microscope. The use of gold surfaces removes some theoretical uncertainties in the interpretation of the measurement. The forces are also measured at smaller surface separations. The complete dielectric spectrum of the metal is used in the comparison of theory to the experiment. The average statistical precision remains at the same 1% of the forces measured at the closest separation. These results should lead to the development of stronger constraints on hypothetical forces. PACS number͑s͒: 12.20.Fv The Casimir force ͓1,2͔ has its origin in the zero-point electromagnetic vacuum fluctuations predicted by quantum electrodynamics. If two perfectly reflecting metal plates are held parallel, then the alteration of the zero-point energy by the metal boundaries leads to an attractive force between the plates called the Casimir force ͓1,2͔. Lifshitz ͓3͔ generalized the force to any two infinite dielectric half-spaces as the force between fluctuating dipoles induced by the zero-point electromagnetic fields and obtained the same result as Casimir for two perfectly reflecting ͑infinite conductivity͒ flat plates. The Casimir force has been demonstrated between two flat plates ͓4͔ and a large sphere and a flat plate ͓5,6͔ and its value shown to be in agreement with the theory to an average deviation of 1% ͓7-9͔. For dielectric bodies the resulting force has been measured with reasonable agreement to the theory ͓10͔. Theoretical treatments of the Casimir force have shown that it is a strong function of the boundary geometry and spectrum ͓11-13͔. Experiments with periodically corrugated boundaries have also demonstrated the nontrivial boundary dependence of the Casimir force ͓14͔. Here we report an improved precision measurement of the Casimir force between a metallized sphere of diameter 191.3 m and a flat plate using an atomic force microscope ͑AFM͒. The use of gold surfaces and the related experimental changes are the primary differences between the experiments reported here and the last version of the experiment ͓9͔. In the previous experiments ͓7,9͔, Al surfaces were used due to their high reflectivity and ease of fabrication. However, in order to prevent the effects of oxidation of the Al surfaces, a thin layer of sputtered Au/Pd was used on top of the Al surface. This thin Au/Pd coating was treated in a phenomenological manner in the earlier experiments ͓7-9͔. A more complete theoretical treatment is complicated as nonlocal effects such as spatial dispersion need to be taken into account in the calculation of the Casimir force ͓15͔. Thus it is necessary to use chemically inert materials such as gold for the measurement of the Casimir force that is reported here. The complete dielectric properties of Au is used in the theory. An important application of Casimir force measurements is to develop strong limits on hypothetical long-range forces ...

The precision instrumental developments and the modern unification theories using compact dimensions have motivated a resurgence in the field of Casimir force measurements. Here, after a brief discussion of the history of Casimir force measurements, the experimental results of Casimir force measurements using an Atomic Force Microscope will be presented. Precision measurements of the normal Casimir force, demonstration of the shape dependent Casimir force and the lateral Casimir force will be presented.

No abstract