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Posted: Dec 06, 2013
Casimir Force reduction through nanostructuring
(Nanowerk News) By nanostructuring one of two interacting metal surfaces at scales below the plasma wavelength, a new regime in the Casimir force was observed by researchers in the Center for Nanoscale Materials Nanofabrication & Devices Group working with collaborators at NIST, other national laboratories, and universities ("Strong Casimir force reduction through metallic surface nanostructuring"). Replacing a flat surface with a deep metallic lamellar grating with <100 nm features strongly suppresses the Casimir force and, for large intersurface separations, reduces it beyond what is theoretically predicted.
(a) Configuration used to measure the Casimir force between a gold-coated sphere and a nanostructured grating. The sphere is attached to the torsional plate of a micromechanical oscillator and the nanostructured grating is fixed to a single-mode optical fiber. SEM images: (b) nanostructured grating limited by two uniform films (scale bar, 100 Ám). (c) Magnified grating showing the high spatial uniformity (scale bar, 400 nm). (d) cross-section of a single grating element (scale bar, 100 nm).
The new Casimir force regime is significantly different from the well-known attraction between parallel plates and is characterized by a crossover from enhancement to strong reduction of the Casimir force. Manipulation of the Casimir force has potential technological applications in micro- and nanoelectromechanical systems switches, quantum computing, and searches for non-Newtonian gravity.
CNM's state-of-the-art lithography capabilities combined with plating technology were critical to the experimental configuration. The Casimir force was measured between a gold sphere and a nanostructured metal grating. An optical fiber monitored the distance to a supporting substrate, and an oscillator measured the Casimir interaction.