The Casimir effect in microstructured geometries

Rodríguez, Alejandro W.; Capasso, Federico; Johnson, Steven G.

doi:10.1038/nphoton.2011.39

Cited by 429 publications

(450 citation statements)

References 116 publications

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“…A more realistic physical description should include dispersion and dissipation, and Lifshitz theory offers this apparatus [2], one that has been applied to experiments with success [3,4] (although some doubts over Lifshitz theory remain [5], due, e.g., to the strange results it produces for media with a finite dc conductivity). The formalism is written in terms of the electromagnetic Green's function, which describes the field produced by sources of current within the system.…”

Section: Introductionmentioning

confidence: 99%

Divergence of Casimir stress in inhomogeneous media

2013

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We examine the local behavior of the regularized stress tensor commonly used in calculations of the Casimir force for a dielectric medium inhomogeneous in one direction. It is shown that the usual expression for the stress tensor is not finite anywhere within the medium, whatever the temporal dispersion or index profile, and that this divergence is unlikely to be removed through a simple modification to the regularization procedure. Our analytic argument is illustrated numerically for a medium approximated as a series of homogeneous strips, as the width of these strips is taken to zero. The findings hold for all magnetodielectric media.

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Section: Introductionmentioning

confidence: 99%

Divergence of Casimir stress in inhomogeneous media

2013

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“…Developments of novel measurement protocols based on driven 2D trajectories will permit both increasing the measurement speed and improving the sensitivity, while simultaneous observation of several longitudinal modes families [19] will further enrich the imaging capacity of our vectorial force probe. In particular, it could be straightforwardly employed to explore proximity forces at the nanoscale, such as Casimir forces in nano-structured samples where novel phenomenology can be expected [39][40][41]. The method is also compatible with non-conservative force field imaging and will permit further exploration of fluctuation theorems in 2D.…”

Section: Conclusion-mentioning

confidence: 99%

A universal and ultrasensitive vectorial nanomechanical sensor for imaging 2D force fields

et al. 2016

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Miniaturization of force probes into nanomechanical oscillators enables ultrasensitive investigations of forces on dimensions smaller than their characteristic length scale. Meanwhile it also unravels the force field vectorial character and how its topology impacts the measurement. Here we expose an ultrasensitive method to image 2D vectorial force fields by optomechanically following the bidimensional Brownian motion of a singly clamped nanowire. This novel approach relies on angular and spectral tomography of its quasi frequency-degenerated transverse mechanical polarizations: immersing the nanoresonator in a vectorial force field does not only shift its eigenfrequencies but also rotate eigenmodes orientation as a nano-compass. This universal method is employed to map a tunable electrostatic force field whose spatial gradients can even take precedence over the intrinsic nanowire properties. Enabling vectorial force fields imaging with demonstrated sensitivities of attonewton variations over the nanoprobe Brownian trajectory will have strong impact on scientific exploration at the nanoscale.Introduction-Nanosciences were revolutionized by the invention of atomic force microscopy [1] which enabled first perceptions of the nanoworld, by measuring proximity forces exerted by a sample on a micromechanical oscillator. The subsequent emergence of nanomechanical oscillators and evolutions in readout techniques [2][3][4] lead to impressive improvements in force sensitivity [5], enabling detection of collective spin dynamics [6][7][8], single electron spin [9], mass sensing of atoms [10,11] or inertial sensing [12]. Attractive perspectives arise too when nanoresonators are hybridized to single quantum systems, such as molecular magnets [13], spin or solid states qubits [14][15][16][17]. This reduction of the probe size naturally motivates the exploration of force fields on dimensions smaller than their characteristic length scale where a great physical richness is expected, in particular for nanoscale imaging or investigations of fundamental interactions such as proximity forces or near field couplings. In this situation, measurements are performed in presence of strong force field gradients whose vectorial structure becomes crucially relevant and should be fully accounted to describe the measurement process itself [18].

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“…Such interactions are important not only for many fundamental phenomena throughout the fields of biology, chemistry, and physics but also for the design and performance of micro-and nano-structured devices. While Casimir forces can be both attractive or repulsive, depending on the nature of the fluctuations (quantum and/or thermal) and the spatial structure (topology and/or geometry) of the interacting systems [5][6][7][8], it is undisputed common wisdom that nonretarded vdW interactions between two objects in vacuo are inherently attractive [9][10][11]. The universality of vdW attraction is attributed to the ubiquitous zero-point energy lowering, induced by dipolar coupling between fluctuating electron charge densities [9,10].…”

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confidence: 99%

Long-Range Repulsion Between Spatially Confined van der Waals Dimers

Sadhukhan

Tkatchenko

2017

Phys. Rev. Lett.

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It is an undisputed textbook fact that nonretarded van der Waals (vdW) interactions between isotropic dimers are attractive, regardless of the polarizability of the interacting systems or spatial dimensionality. The universality of vdW attraction is attributed to the dipolar coupling between fluctuating electron charge densities. Here, we demonstrate that the long-range interaction between spatially confined vdW dimers becomes repulsive when accounting for the full Coulomb interaction between charge fluctuations. Our analytic results are obtained by using the Coulomb potential as a perturbation over dipole-correlated states for two quantum harmonic oscillators embedded in spaces with reduced dimensionality; however, the longrange repulsion is expected to be a general phenomenon for spatially confined quantum systems. We suggest optical experiments to test our predictions, analyze their relevance in the context of intermolecular interactions in nanoscale environments, and rationalize the recent observation of anomalously strong screening of the lateral vdW interactions between aromatic hydrocarbons adsorbed on metal surfaces. DOI: 10.1103/PhysRevLett.118.210402 Interactions induced by quantum-mechanical charge density fluctuations, such as van der Waals (vdW) and Casimir forces, are always present between objects with finite dimensions [1][2][3][4]. Such interactions are important not only for many fundamental phenomena throughout the fields of biology, chemistry, and physics but also for the design and performance of micro-and nano-structured devices. While Casimir forces can be both attractive or repulsive, depending on the nature of the fluctuations (quantum and/or thermal) and the spatial structure (topology and/or geometry) of the interacting systems [5][6][7][8], it is undisputed common wisdom that nonretarded vdW interactions between two objects in vacuo are inherently attractive [9][10][11]. The universality of vdW attraction is attributed to the ubiquitous zero-point energy lowering, induced by dipolar coupling between fluctuating electron charge densities [9,10].However, many biological, chemical, and physical phenomena of importance in materials happen in spatially confined environments, as opposed to isotropic and homogeneous vacuum. The confinement can be artificially engineered by applying static or dynamic electromagnetic fields or arise as a result of the encapsulation of molecules in nanotubes, fullerenes, and/or by adsorption on polarizable surfaces. Moreover, in biological systems, proteins are typically confined in an inhomogeneous environment. We remark that even when such confinement entails tiny modification of the electron density (having no apparent effect on the electrostatics), it can visibly affect the interactions stemming from density fluctuations due to their long-range inhomogeneous nature.Here, we demonstrate that the breaking of rotational and/or translational symmetry of 3D vacuum results in repulsive long-range interactions for vdW dimers.The repulsive interaction stems from...

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The Casimir effect in microstructured geometries

Cited by 429 publications

References 116 publications

Divergence of Casimir stress in inhomogeneous media

Divergence of Casimir stress in inhomogeneous media

A universal and ultrasensitive vectorial nanomechanical sensor for imaging 2D force fields

Long-Range Repulsion Between Spatially Confined van der Waals Dimers

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