Strong Casimir force reduction through metallic surface nanostructuring

Abstract

The Casimir force between bodies in vacuum can be understood as arising from their interaction with an infinite number of fluctuating electromagnetic quantum vacuum modes, resulting in a complex dependence on the shape and material of the interacting objects. Becoming dominant at small separations, the force has a significant role in nanomechanics and object manipulation at the nanoscale, leading to a considerable interest in identifying structures where the Casimir interaction behaves significantly different from the well-known attractive force between parallel plates. Here we experimentally demonstrate that by nanostructuring one of the interacting metal surfaces at scales below the plasma wavelength, an unexpected regime in the Casimir force can be observed. Replacing a flat surface with a deep metallic lamellar grating with sub-100 nm features strongly suppresses the Casimir force and for large inter-surfaces separations reduces it beyond what would be expected by any existing theoretical prediction.

Casimir-Lifshitz force out of thermal equilibrium between dielectric gratings

“…More recently, nanostructured surfaces have been theoretically considered in the contexts of both force [32][33][34][35] and heat transfer [36,37]. Experimentally, the force has been measured between a sphere and a dielectric [38,39] or metallic [40] grating.…”

Charge-Induced Fluctuation Forces in Graphitic Nanostructures

“…As the separation is further increased to 0.6 μm, the chargeinduced fluctuation force becomes 17 Pa, which is almost double the Casimir interaction of 10 Pa at that distance. We note that fluctuation-induced interactions of this magnitude can be accessed experimentally, as shown for the Casimir regime [21,38]. Therefore, we suggest that measurements in a nanocapacitor with and without the connecting wire might give means to distinguish between the typical Casimir and charge-induced Casimir-like interactions in an experimental setting.…”

“…While the Casimir phenomenon is due to the electromagnetic fluctuation excitations associated with the dielectric and magnetic response of each plate, the charge-induced effect is due to monopolar charge fluctuations between the plates transferred through the wire. Since in many cases nanostructures are characterized by a reduced Casimir force as compared to 3D [19][20][21][22], nanocapacitors offer the possibility of finding regimes where the charge-induced fluctuation interaction can be dominant.…”

Calculating Casimir interactions for periodic surface-relief gratings using theCmethod

“…There have been a number of experiments showing that the magnitude of the Casimir force could be varied by changing the surface geometry of the interacting objects [5][6][7][8][9][10][11][12][13][14]. To investigate the impact of curvature and corrugation, the Casimir forces have been measured between a sphere and a sinusoidal grating [5] and between two corrugated surfaces for both aligned [6,7] and crossed [13,14] corrugations.…”