Casimir Forces and Quantum Electrodynamical Torques: Physics and Nanomechanics

Capasso, Federico; Munday, Jeremy N.; Iannuzzi, Davide; Chan, H. B.

doi:10.1109/jstqe.2007.893082

Cited by 243 publications

(291 citation statements)

References 99 publications

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“…Since its prediction [2], the critical Casimir effect has attracted numerous theoretical investigations (see, e.g., Refs. [3] and [4] and references therein) revealing both an intriguing instance of solvent-mediated effective interactions and a classical analogue of the celebrated Casimir effect in quantum electrodynamics [5][6][7][8].…”

Section: Introductionmentioning

confidence: 99%

Alignment of cylindrical colloids near chemically patterned substrates induced by critical Casimir torques

et al. 2014

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Recent experiments have demonstrated a fluctuation-induced lateral trapping of spherical colloidal particles immersed in a binary liquid mixture near its critical demixing point and exposed to chemically patterned substrates. Inspired by these experiments, we study this kind of effective interaction, known as the critical Casimir effect, for elongated colloids of cylindrical shape. This adds orientational degrees of freedom. When the colloidal particles are close to a chemically structured substrate, a critical Casimir torque acting on the colloids emerges. We calculate this torque on the basis of the Derjaguin approximation. The range of validity of the latter is assessed via mean-field theory. This assessment shows that the Derjaguin approximation is reliable in experimentally relevant regimes, so that we extend it to Janus particles endowed with opposing adsorption preferences. Our analysis indicates that critical Casimir interactions are capable of achieving well-defined, reversible alignments both of chemically homogeneous and of Janus cylinders.

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Section: Introductionmentioning

confidence: 99%

Alignment of cylindrical colloids near chemically patterned substrates induced by critical Casimir torques

et al. 2014

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“…This effect manifests itself as an attractive force arising between two uncharged bodies due to the difference of the zero-point oscillation spectrum in the absence and in the presence of these bodies (see, e.g., Refs. [1,2,3,4]). …”

Section: Introductionmentioning

confidence: 99%

Temperature dependence of the Casimir force for bulk lossy media

et al. 2010

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We discuss the limitations of the applicability of the Lifshitz formula to describe the temperature dependence of the Casimir force between two bulk lossy metals. These limitations follow from the finite sizes of the interacting bodies. Namely, Lifshitz's theory is not applicable when the characteristic wavelengths of the fluctuating fields, responsible for the temperature-dependent terms in the Casimir force, is longer than the sizes of the samples. As a result of this, the widely discussed linearly decreasing temperature dependence of the Casimir force can be observed only for dirty and/or large metal samples at high enough temperatures. This solves the problem of the inconsistency between the Nernst theorem and the "linearly decreasing temperature dependence" of the Casimir free energy, because this linear dependence is not valid when T → 0.

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“…Casimir forces arise from quantum vacuum fluctuations, and have been the subject of considerable theoretical and experimental interest [1,2,3,4]. We consider here the force between metallic cylinders with one or two parallel metal sidewalls ( Fig.…”

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confidence: 99%

Nonmonotonic effects of parallel sidewalls on Casimir forces between cylinders

et al. 2008

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We analyze the Casimir force between two parallel infinite metal cylinders, with nearby metal plates (sidewalls), using complementary methods for mutual confirmation. The attractive force between cylinders is shown to have a nonmonotonic dependence on the separation to the plates. This intrinsically multi-body phenomenon, which occurs with either one or two sidewalls (generalizing an earlier result for squares between two sidewalls), does not follow from any simple two-body force description. We can, however, explain the nonmonotonicity by considering the screening (enhancement) of the interactions by the fluctuating charges (currents) on the two cylinders, and their images on the nearby plate(s). Furthermore, we show that this effect also implies a nonmonotonic dependence of the cylinder-plate force on the cylinder-cylinder separation.PACS numbers: 12.20. Ds, 42.50.Ct, 42.50.Lc Casimir forces arise from quantum vacuum fluctuations, and have been the subject of considerable theoretical and experimental interest [1,2,3,4]. We consider here the force between metallic cylinders with one or two parallel metal sidewalls ( Fig. 1) using two independent exact computational methods, and find an unusual nonmonotonic dependence of the force on the sidewall separation. These nonmonotonic effects cannot be predicted by commonly used two-body Casimir-force estimates, such as the proximity-force approximation (PFA) [5,6] that is based on the parallel-plate limit, or by addition of Casimir-Polder 'atomic' interactions (CPI) [6,7,8].In previous work, we demonstrated a similar nonmonotonic force between two metal squares in proximity to two parallel metal sidewalls, for either perfect or realistic metals [9]. This work, with perfect-metal cylinders [10], demonstrates that the effect is not limited to squares (i.e., it does not arise from sharp corners or parallel flat surfaces), nor does it require two sidewalls. The nonmonotonicity stems from a competition between forces from transverse electric (TE) and transverse magnetic (TM) field polarizations: In the latter case, the interaction between fluctuating charges on the cylinders is screened by opposing image charges, in the former case it is enhanced by analogous fluctuating image currents. Furthermore, we show that a related nonmonotonic variation arises for the force between the cylinders and a sidewall as a function of separation between the cylinders, a geometry potentially amenable to experiment.Casimir forces are not two-body interactions: quantum fluctuations in one object induce fluctuations throughout the system which in turn act back on the first object. However, both the PFA and CPI view Casimir forces as the result of attractive two-body ("pairwise") interactions. They are reasonable approximations only in certain limits (e.g., low curvature for PFA), and can fail qualitatively as well as quantitatively otherwise. Pairwise estimates fail to account for two important aspects of the Casimir forces in the geometry we consider [11]. First, a monotonic pairwise attrac...

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Casimir Forces and Quantum Electrodynamical Torques: Physics and Nanomechanics

Cited by 243 publications

References 99 publications

Alignment of cylindrical colloids near chemically patterned substrates induced by critical Casimir torques

Alignment of cylindrical colloids near chemically patterned substrates induced by critical Casimir torques

Temperature dependence of the Casimir force for bulk lossy media

Nonmonotonic effects of parallel sidewalls on Casimir forces between cylinders

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