Repulsive Casimir Force in Chiral Metamaterials

First predicted by distinguished Dutch physicist, H.B.G. Casimir in 1948, the Casimir force arises when two uncharged, parallel metallic plates are brought in close proximity. Noticeable at a distance of a few microns, this attracting force becomes dominant at a length scale of tens of nanometers. Classically, no force exists between the plates; the Casimir force is proportional to the surface’s area, a consequence of the quantum nature of the electromagnetic field. Not restricted to parallel plates, the Casimir force exists between any two objects for microscopic separations. This attracting Casimir effect causes parts in micromechanical and, even more severely, nanoscale devices to stick together, leading to friction and restricting functionality; thus, limiting further miniaturization of mechanical devices.


Recent published work shows it is possible to reverse the direction of the Casimir force, using-specially designed chiral metamaterials. A chiral metamaterial is an artificially-engineered material, whose properties are not readily found in nature and cannot be superimposed on itself. They can provide a new way to obtain a repulsive force and nanolevitation. If experimentalists fabricate these chiral metamaterials, new applications will be realized in micro- and nanomechanical systems, and one can envision frictionless machines.


Relevant Publication(s): R. Zhao, J. Zhou, Th. Koschny, E.N. Economou and C.M. Soukoulis, Phys. Rev. Lett. 103, 103602 (2009); R. Zhao, Th. Koschny, E.N. Economou and C.M. Soukoulis, Phys. Rev. B 81, 235126 (2010).