The Casimir Effect is a physical manifestation of quantum fluctuations of the electromagnetic vacuum. When two metal plates are placed close together, typically much less than a micron, the long wavelength modes between them are frozen out, giving rise to a net attractive force between the plates, scaling as d−4 (or d−3 for a spherical-planar geometry) even when they are not electrically charged. In this paper, we observe the Casimir Effect in ambient conditions using a modified capacitive micro-electromechanical system (MEMS) sensor. Using a feedback-assisted pick-and-place assembly process, we are able to attach various microstructures onto the post-release MEMS, converting it from an inertial force sensor to a direct force measurement platform with pN (piconewton) resolution. With this system we are able to directly measure the Casimir force between a silver-coated microsphere and gold-coated silicon plate. This device is a step towards leveraging the Casimir Effect for cheap, sensitive, room temperature quantum metrology.
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The Casimir effect in graphene systems: Experiment and theory
The Casimir effect in graphene systems is reviewed with a emphasis made on the large thermal correction to the Casimir force predicted at short separations between the test bodies. The computational results for the Casimir pressure and for the thermal correction are presented for both pristine graphene and real graphene sheets, which possess nonzero energy gap and chemical potential, obtained by means of exact polarization tensor. Two experiments on measuring the gradient of the Casimir force between an Au-coated sphere and graphene-coated substrates performed by using a modified atomic force microscope cantilever-based technique are described. It is shown that the measurement data of both experiments are in agreement with theoretical predictions of the Lifshitz theory using the polarization tensor. Additionally, several important improvements made in the second experiment, allowed to demonstrate the predicted large thermal effect in the Casimir interaction at short separations. Possible implications of this result to the resolution of long-term problems of Casimir physics are discussed.
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- Award ID(s):
- 2012201
- NSF-PAR ID:
- 10343019
- Date Published:
- Journal Name:
- International Journal of Modern Physics A
- ISSN:
- 0217-751X
- Format(s):
- Medium: X
- Sponsoring Org:
- National Science Foundation
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The Casimir Effect is a physical manifestation of quantum fluctuations of the electromagnetic vacuum. When two metal plates are placed close together, typically much less than a micron, the long wavelength modes between them are frozen out, giving rise to a net attractive force between the plates, scaling as d−4 (or d−3 for a spherical-planar geometry) even when they are not electrically charged. In this paper, we observe the Casimir Effect in ambient conditions using a modified capacitive micro-electromechanical system (MEMS) sensor. Using a feedback-assisted pick-and-place assembly process, we are able to attach various microstructures onto the post-release MEMS, converting it from an inertial force sensor to a direct force measurement platform with pN (piconewton) resolution. With this system we are able to directly measure the Casimir force between a silver-coated microsphere and gold-coated silicon plate. This device is a step towards leveraging the Casimir Effect for cheap, sensitive, room temperature quantum metrology.more » « less
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Quantum and thermal fluctuations are fundamental to a plethora of phenomena within quantum optics, including the Casimir effect that acts between closely separated surfaces typically found in microelectromechanical systems (MEMS) and nanoelectromechanical systems (NEMS) devices. Particularly promising for engineering and harnessing these forces are systems out of thermal equilibrium. Recently, semiconductors with external bias have been proposed to study the nonequilibrium Casimir force. Here, we explore systems involving moderately biased semiconductors that exhibit strong repulsive Casimir forces, and we determine the effects of bias voltage, semiconductor bandgap energy, and separation for experimentally accessible configurations. Modes emitted from the semiconductors exert a repulsive force on a near surface that overcomes the attractive equilibrium Casimir force contribution at submicron distances. For the geometry of two parallel planes, those modes undergo Fabry–Pérot interference resulting in an oscillatory force behavior as a function of separation. Utilizing the proximity-force approximation, we predict that the repulsive force exerted on a gold sphere is well within the accuracy of typical Casimir force experiments. Our work opens up new possibilities for controlling forces at the nanometer and micrometer scale with applications in sensing and actuation in nanotechnology.
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Abstract In this article, we present a nanoelectromechanical system (NEMS) designed to detect changes in the Casimir energy. The Casimir effect is a result of the appearance of quantum fluctuations in an electromagnetic vacuum. Previous experiments have used nano- or microscale parallel plate capacitors to detect the Casimir force by measuring the small attractive force these fluctuations exert between the two surfaces. In this new set of experiments, we aim to directly detect the shifts in the Casimir energy in a vacuum due to the presence of the metallic parallel plates, one of which is a superconductor. A change in the Casimir energy of this configuration is predicted to shift the superconducting transition temperature (
T c) because of the interaction between it and the superconducting condensation energy. In our experiment, we take a superconducting film, carefully measure its transition temperature, bring a conducting plate close to the film, create a Casimir cavity, and then measure the transition temperature again. The expected shifts are smaller than the normal shifts one sees in cycling superconducting films to cryogenic temperatures, so using a NEMS resonator in situ is the only practical way to obtain accurate, reproducible data. Using a thin Pb film and opposing Au surface, we observe no shift inT c>12 µK down to a minimum spacing of ~70 nm at zero applied magnetic field. -
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- Free Publicly Accessible Full Text
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Accepted Manuscript1.0
- Journal Article:
- https://doi.org/10.1142/S0217751X22410032
