Stable Levitation and Alignment of Compact Objects by Casimir Spring Forces

Department of Physics, Massachusetts Institute of Technology, Cambridge, Massachusetts 02139, USA.
Physical Review Letters (Impact Factor: 7.73). 02/2010; 104(7):070405. DOI: 10.1103/PhysRevLett.104.070405
Source: arXiv

ABSTRACT We investigate a stable Casimir force configuration consisting of an object contained inside a spherical or spheroidal cavity filled with a dielectric medium. The spring constant for displacements from the center of the cavity and the dependence of the energy on the relative orientations of the inner object and the cavity walls are computed. We find that the stability of the force equilibrium-unlike the direction of the torque-can be predicted based on the sign of the force between two slabs of the same material.

  • Source
    [Show abstract] [Hide abstract]
    ABSTRACT: We predict that a low-permittivity oblate body (disk-shaped object) above a thin metal substrate (plate with a hole) immersed in a fluid of intermediate permittivity will experience a metastable equilibrium (restoring force) near the center of the hole. Stability is the result of a geometry-induced transition in the sign of the force, from repulsive to attractive, that occurs as the disk approaches the hole-in planar or nearly planar geometries, the same material combination yields a repulsive force at all separations, in accordance with the Dzyaloshinskiĭ-Lifshitz-Pitaevskiĭ condition of fluid-induced repulsion between planar bodies. We explore the stability of the system with respect to rotations and lateral translations of the disks and demonstrate interesting transitions (bifurcations) in the rotational stability of the disks as a function of their size. Finally, we consider the reciprocal situation in which the disk-plate materials are interchanged and find that in this case the system also exhibits metastability. The forces in the system are sufficiently large to be observed in experiments and should enable measurements based on the diffusion dynamics of the suspended bodies.
    Physical Review Letters 11/2013; 111(18):180402. DOI:10.1103/PhysRevLett.111.180402 · 7.73 Impact Factor
  • Source
    [Show abstract] [Hide abstract]
    ABSTRACT: The Casimir force between two surfaces is attractive in most cases. Although stable suspension of nano-objects has been achieved, the sophisticated geometries make them difficult to be merged with well-established thin film processes. We find that by introducing thin film surface coating on porous substrates, a repulsive to attractive force transition is achieved when the separations are increased in planar geometries, resulting in a stable suspension of two surfaces near the force transition separation. Both the magnitude of the force and the transition distance can be flexibly tailored though modifying the properties of the considered materials, that is, thin film thickness, doping concentration, and porosity. This stable suspension can be used to design new nanodevices with ultralow friction. Moreover, it might be convenient to merge this thin film coating approach with micro-and nanofabrication processes in the future.
    Physical Review B 01/2014; 89(20). DOI:10.1103/PhysRevB.89.201407 · 3.66 Impact Factor
  • [Show abstract] [Hide abstract]
    ABSTRACT: It is shown that the electromagnetic Casimir force acting on a conducting body (e.g., a realistic metallic piston) sliding in a background formed by cut silver nanorods (with the body perforated by the nanorods) is repulsive at distances larger than the separation of the nanorods, even if the host material of the nanorods is air. It is demonstrated that the physical origin of this effect is in essence related to Boyer’s prediction that magnetic and conducting walls repel each other. Indeed, we show that from the point of view of an observer inside the nanowire structure, the interface formed by severing the nanowires mimics accurately the behavior of a magnetic wall for P-polarized waves. In contrast to other piston configurations reported in the literature, the Casimir interaction in the nanowire background is an ultralong-range force that decays with the distance to the nearby interface as 1/a2.
    Physical Review A 02/2011; 83(2):022508. DOI:10.1103/PhysRevA.83.022508 · 3.04 Impact Factor

Full-text (4 Sources)

Available from
May 17, 2014