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Sample records for casimir effect

  1. Casimir effect: The classical limit

    International Nuclear Information System (INIS)

    Feinberg, J.; Mann, A.; Revzen, M.

    2001-01-01

    We analyze the high temperature (or classical) limit of the Casimir effect. A useful quantity which arises naturally in our discussion is the 'relative Casimir energy', which we define for a configuration of disjoint conducting boundaries of arbitrary shapes, as the difference of Casimir energies between the given configuration and a configuration with the same boundaries infinitely far apart. Using path integration techniques, we show that the relative Casimir energy vanishes exponentially fast in temperature. This is consistent with a simple physical argument based on Kirchhoff's law. As a result the 'relative Casimir entropy', which we define in an obviously analogous manner, tends, in the classical limit, to a finite asymptotic value which depends only on the geometry of the boundaries. Thus the Casimir force between disjoint pieces of the boundary, in the classical limit, is entropy driven and is governed by a dimensionless number characterizing the geometry of the cavity. Contributions to the Casimir thermodynamical quantities due to each individual connected component of the boundary exhibit logarithmic deviations in temperature from the behavior just described. These logarithmic deviations seem to arise due to our difficulty to separate the Casimir energy (and the other thermodynamical quantities) from the 'electromagnetic' self-energy of each of the connected components of the boundary in a well defined manner. Our approach to the Casimir effect is not to impose sharp boundary conditions on the fluctuating field, but rather take into consideration its interaction with the plasma of 'charge carriers' in the boundary, with the plasma frequency playing the role of a physical UV cutoff. This also allows us to analyze deviations from a perfect conductor behavior

  2. Casimir effect and the quantum vacuum

    International Nuclear Information System (INIS)

    Jaffe, R.L.

    2005-01-01

    In discussions of the cosmological constant, the Casimir effect is often invoked as decisive evidence that the zero-point energies of quantum fields are ''real.'' On the contrary, Casimir effects can be formulated and Casimir forces can be computed without reference to zero-point energies. They are relativistic, quantum forces between charges and currents. The Casimir force (per unit area) between parallel plates vanishes as α, the fine structure constant, goes to zero, and the standard result, which appears to be independent of α, corresponds to the α→∞ limit

  3. Reducing detrimental electrostatic effects in Casimir-force measurements and Casimir-force-based microdevices

    Science.gov (United States)

    Xu, Jun; Klimchitskaya, G. L.; Mostepanenko, V. M.; Mohideen, U.

    2018-03-01

    It is well known that residual electrostatic forces create significant difficulties in precise measurements of the Casimir force and the wide use of Casimir-operated microdevices. We experimentally demonstrate that, with the help of Ar-ion cleaning of the surfaces, it is possible to make electrostatic effects negligibly small compared to the Casimir interaction. Our experimental setup consists of a dynamic atomic force microscope supplemented with an Ar-ion gun and argon reservoir. The residual potential difference between the Au-coated surfaces of a sphere and those of a plate was measured both before and after in situ Ar-ion cleaning. It is shown that this cleaning decreases the magnitude of the residual potential by up to an order of magnitude and makes it almost independent of the separation. The gradient of the Casimir force was measured using ordinary samples subjected to Ar-ion cleaning. The obtained results are shown to be in good agreement both with previous precision measurements using specially selected samples and with theoretical predictions of the Lifshitz theory. The conclusion is made that the suggested method of in situ Ar-ion cleaning is effective in reducing the electrostatic effects and therefore is a great resource for experiments on measuring the Casimir interaction and for Casimir-operated microdevices.

  4. Nonperturbative Dynamical Casimir Effect in Optomechanical Systems: Vacuum Casimir-Rabi Splittings

    Directory of Open Access Journals (Sweden)

    Vincenzo Macrì

    2018-02-01

    Full Text Available We study the dynamical Casimir effect using a fully quantum-mechanical description of both the cavity field and the oscillating mirror. We do not linearize the dynamics, nor do we adopt any parametric or perturbative approximation. By numerically diagonalizing the full optomechanical Hamiltonian, we show that the resonant generation of photons from the vacuum is determined by a ladder of mirror-field vacuum Rabi splittings. We find that vacuum emission can originate from the free evolution of an initial pure mechanical excited state, in analogy with the spontaneous emission from excited atoms. By considering a coherent drive of the mirror, using a master-equation approach to take losses into account, we are able to study the dynamical Casimir effect for optomechanical coupling strengths ranging from weak to ultrastrong. We find that a resonant production of photons out of the vacuum can be observed even for mechanical frequencies lower than the cavity-mode frequency. Since high mechanical frequencies, which are hard to achieve experimentally, were thought to be imperative for realizing the dynamical Casimir effect, this result removes one of the major obstacles for the observation of this long-sought effect. We also find that the dynamical Casimir effect can create entanglement between the oscillating mirror and the radiation produced by its motion in the vacuum field, and that vacuum Casimir-Rabi oscillations can occur. Finally, we also show that all these findings apply not only to optomechanical systems, but also to parametric amplifiers operating in the fully quantum regime.

  5. Casimir effect on the brane

    International Nuclear Information System (INIS)

    Flachi, Antonino; Tanaka, Takahiro

    2009-01-01

    We consider the Casimir effect between two parallel plates localized on a brane. We argue that in order to properly compute the contribution to the Casimir energy due to any higher dimensional field, it is necessary to take into account the localization properties of the Kaluza-Klein modes. When the bulk field configuration is such that no massless mode appears in the spectrum, as, for instance, when the higher dimensional field obeys twisted boundary conditions across the branes, the correction to the Casimir energy is exponentially suppressed. When a massless mode is present in the spectrum, the correction to the Casimir energy can be, in principle, sizeable. However, when the bulk field is massless and strongly coupled to brane matter, the model is already excluded without resorting to any Casimir force experiment. The case which is in principle interesting is when the massless mode is not localized on the visible brane. We illustrate a method to compute the Casimir energy between two parallel plates, localized on the visible brane, approximating the Kaluza-Klein spectrum by truncation at the first excited mode. We treat this case by considering a pistonlike configuration and introduce a small parameter, ε, that takes into account the relative amplitude of the zero-mode wave function on the visible brane with respect to the massive excitation. We find that the Casimir energy is suppressed by two factors: at lowest order in ε, the correction to the Casimir energy comes entirely from the massive mode and turns out to be exponentially suppressed; the next-to-leading order correction in ε follows, instead, a power-law suppression due to the small wave-function overlap of the zero mode with matter confined on the visible brane. Generic comments on the constraints on new physics that may arise from Casimir force experiments are also made.

  6. The Casimir effect: medium and geometry

    International Nuclear Information System (INIS)

    Marachevsky, Valery N

    2012-01-01

    Theory of the Casimir effect is presented in several examples. Casimir–Polder-type formulas, Lifshitz theory and theory of the Casimir effect for two gratings separated by a vacuum slit are derived. Equations for the electromagnetic field in the presence of a medium and dispersion are discussed. The Casimir effect for systems with a layer of 2 + 1 fermions is studied. This article is part of a special issue of Journal of Physics A: Mathematical and Theoretical in honour of Stuart Dowker's 75th birthday devoted to ‘Applications of zeta functions and other spectral functions in mathematics and physics’. (paper)

  7. Casimir effect in the presence of metamaterials

    Energy Technology Data Exchange (ETDEWEB)

    Kort-Kamp, W.J.M.; Pinheiro, F.A.; Maia Neto, P.A.; Farina, C. [Universidade Federal do Rio de Janeiro (UFRJ), RJ (Brazil); Rosa, F.S.S. [Universite Paris-Sud (France). Lab. Charles Fabry

    2011-07-01

    Full text: The Casimir effect was theoretically predicted in 1948 by H. G. B. Casimir. In its original form, it is the attraction between two parallel plates made of perfectly conductors in vacuum. The novelty in the Casimir result was the method used and not the fact that two neutral bodies attract each other, since the force between two neutral, but polarizable, atoms was previously treated by London in 1930. Casimir demonstrated that the force between the plates could be calculated from the variation in the zero-point energy of the quantized electromagnetic field caused by the presence of the plates. Nowadays there is no doubt about the existence of this effect, which has been observed in the last decade in experiments of great precision. Casimir forces play an important role in nanotechnology, in particular in the study of micro- and nano-electromechanical systems, because these forces become dominant in the nanoscopic scale. Casimir forces are responsible for an attraction of individual parts of these devices, making them eventually to stick together. As a result, attractive Casimir forces constitute a nuisance for practical applications. Therefore the investigation of a repulsive Casimir force is of great current interest. It has been recently argued that Casimir repulsion could be obtained by an adequate choice of artificial materials, the so-called metamaterials, with engineered electromagnetic properties [R. Zhao et al, PRL 103, 103602 (2009)]. In this work we investigate the interaction between an atom and a chiral metamaterial plate. Using realistic parameters, obtained from recent experiments and computer simulations, we show that state-of-the-art chiral metamaterials are not able generate Casimir repulsive forces. We also investigate the possibility of magneto-optical metamaterials to exhibit a repulsive Casimir force. To accomplish this, we discuss the dispersive interaction between a magneto-optical sphere and a chiral surface or a magneto

  8. Acoustic Casimir Effect

    National Research Council Canada - National Science Library

    Homes, Christopher

    1997-01-01

    ...). When the indirect manifestations of the ZPF are interpreted as due to radiation pressure, acoustic noise can provide an excellent analog to investigate the Casimir effect as well as other effects due to the ZPF...

  9. The Casimir effect: a force from nothing

    International Nuclear Information System (INIS)

    Lambrecht, Astrid

    2003-01-01

    The attractive force between two surfaces in a vacuum - first predicted by Hendrik Casimir over 50 years ago - could affect everything from micro machines to unified theories of nature. What happens if you take two mirrors and arrange them so that they are facing each other in empty space? Your first reaction might be 'nothing at all'. In fact, both mirrors are mutually attracted to each other by the simple presence of the vacuum. This startling phenomenon was first predicted in 1948 by the Dutch theoretical physicist Hendrik Casimir while he was working at Philips Research Laboratories in Eindhoven on - of all things - colloidal solutions (see box). The phenomenon is now dubbed the Casimir effect, while the force between the mirrors is known as the Casimir force. For many years the Casimir effect was little more than a theoretical curiosity. But interest in the phenomenon has blossomed in recent years. Experimental physicists have realized that the Casimir force affects the workings of micro machined devices, while advances in instrumentation have enabled the force to be measured with ever-greater accuracy. The new enthusiasm has also been fired by fundamental physics. Many theorists have predicted the existence of 'large' extra dimensions in 10- and 11-dimensional unified field theories of the fundamental forces. These dimensions, they say, could modify classical Newtonian gravitation at sub-millimetre distances. Measuring the Casimir effect could therefore help physicists to test the validity of such radical ideas. (U.K.)

  10. Is zero-point energy physical? A toy model for Casimir-like effect

    International Nuclear Information System (INIS)

    Nikolić, Hrvoje

    2017-01-01

    Zero-point energy is generally known to be unphysical. Casimir effect, however, is often presented as a counterexample, giving rise to a conceptual confusion. To resolve the confusion we study foundational aspects of Casimir effect at a qualitative level, but also at a quantitative level within a simple toy model with only 3 degrees of freedom. In particular, we point out that Casimir vacuum is not a state without photons, and not a ground state for a Hamiltonian that can describe Casimir force. Instead, Casimir vacuum can be related to the photon vacuum by a non-trivial Bogoliubov transformation, and it is a ground state only for an effective Hamiltonian describing Casimir plates at a fixed distance. At the fundamental microscopic level, Casimir force is best viewed as a manifestation of van der Waals forces. - Highlights: • A toy model for Casimir-like effect with only 3 degrees of freedom is constructed. • Casimir vacuum can be related to the photon vacuum by a non-trivial Bogoliubov transformation. • Casimir vacuum is a ground state only for an effective Hamiltonian describing Casimir plates at a fixed distance. • At the fundamental microscopic level, Casimir force is best viewed as a manifestation of van der Waals forces.

  11. Microscopic dynamical Casimir effect

    Science.gov (United States)

    Souza, Reinaldo de Melo e.; Impens, François; Neto, Paulo A. Maia

    2018-03-01

    We consider an atom in its ground state undergoing a nonrelativistic oscillation in free space. The interaction with the electromagnetic quantum vacuum leads to two effects to leading order in perturbation theory. When the mechanical frequency is larger than the atomic transition frequency, the dominant effect is the motion-induced transition to an excited state with the emission of a photon carrying the excess energy. We compute the angular distribution of emitted photons and the excitation rate. On the other hand, when the mechanical frequency is smaller than the transition frequency, the leading-order effect is the parametric emission of photon pairs, which constitutes the microscopic counterpart of the dynamical Casimir effect. We discuss the properties of the microscopic dynamical Casimir effect and build a connection with the photon production by an oscillating macroscopic metallic mirror.

  12. Fermionic Casimir effect with helix boundary condition

    International Nuclear Information System (INIS)

    Zhai, Xiang-hua; Li, Xin-zhou; Feng, Chao-Jun

    2011-01-01

    In this paper, we consider the fermionic Casimir effect under a new type of space-time topology using the concept of quotient topology. The relation between the new topology and that in Feng and Li (Phys. Lett. B 691:167, 2010), Zhai et al. (Mod. Phys. Lett. A 26:669, 2011) is something like that between a Moebius strip and a cylindric. We obtain the exact results of the Casimir energy and force for the massless and massive Dirac fields in the (D+1)-dimensional space-time. For both massless and massive cases, there is a Z 2 symmetry for the Casimir energy. To see the effect of the mass, we compare the result with that of the massless one and we found that the Casimir force approaches the result of the force in the massless case when the mass tends to zero and vanishes when the mass tends to infinity. (orig.)

  13. Johnson noise and the thermal Casimir effect

    International Nuclear Information System (INIS)

    Bimonte, Giuseppe

    2007-01-01

    We study the thermal interaction between two nearby thin metallic wires, at finite temperature. It is shown that the Johnson currents in the wires give rise, via inductive coupling, to a repulsive force between them. This thermal interaction exhibits all the puzzling features found recently in the thermal Casimir effect for lossy metallic plates, suggesting that the physical origin of the difficulties encountered in the Casimir problem resides in the inductive coupling between the Johnson currents inside the plates. We show that in our simple model all puzzles are resolved if account is taken of capacitive effects associated with the end points of the wires. Our findings suggest that capacitive finite-size effects may play an important role in the resolution of the analogous problems met in the thermal Casimir effect

  14. Dynamical Casimir effect with semi-transparent mirrors, and cosmology

    International Nuclear Information System (INIS)

    Elizalde, Emilio

    2008-01-01

    After reviewing some essential features of the Casimir effect and, specifically, of its regularization by zeta function and Hadamard methods, we consider the dynamical Casimir effect (or Fulling-Davies theory), where related regularization problems appear, with a view to an experimental verification of this theory. We finish with a discussion of the possible contribution of vacuum fluctuations to dark energy, in a Casimir-like fashion, that might involve the dynamical version

  15. An ``Anatomic approach" to study the Casimir effect

    Science.gov (United States)

    Intravaia, Francesco; Haakh, Harald; Henkel, Carsten

    2010-03-01

    The Casimir effect, in its simplest definition, is a quantum mechanical force between two objects placed in vacuum. In recent years the Casimir force has been the object of an exponentially growing attention both from theorists and experimentalists. A new generation of experiments paved the way for new challenges and spotted some shadows in the comparison to theory. Here we are going to isolate different contributions to the Casimir interaction and perform a detailed study to shine new light on this phenomenon. As an example, the contributions of Foucault (eddy current) modes will be discussed in different configurations. This ``anatomic approach'' allows to clearly put into evidence special features and to explain unusual behaviors. This brings new physical understanding on the undergoing physical mechanisms and suggests new ways to engineer the Casimir effect.

  16. Casimir effect for interacting fields

    International Nuclear Information System (INIS)

    Kay, B.S.

    1982-01-01

    The author discusses some recent work on the Casimir effect: that is the problem of renormalizing Tsub(μγ) on locally-flat space-times. That is on space-times which, while topologically non-trivial are locally Minkowskian - with vanishing local curvature. The author has developed a systematic method for calculating this Casimir effect for interacting fields to arbitrary order in perturbation theory - and for arbitrary components of Tsub(μγ) which he describes in general and then illustrates it by describing first order perturbation theory calculations for a lambdaphi 4 theory for the two models: the cylinder space-time and the parallel plates. (Auth.)

  17. Maxwell-Chern-Simons Casimir effect. II. Circular boundary conditions

    International Nuclear Information System (INIS)

    Milton, K.A.; Ng, Y.J.

    1992-01-01

    In odd-dimensional spaces, gauge invariance permits a Chern-Simons mass term for the gauge fields in addition to the usual Maxwell-Yang-Mills kinetic energy term. We study the Casimir effect in such a (2+1)-dimensional Abelian theory. The case of parallel conducting lines was considered by us in a previous paper. Here we discuss the Casimir effect for a circle and examine the effect of finite temperature. The Casimir stress is found to be attractive at both low and high temperatures

  18. Experiment, theory and the Casimir effect

    International Nuclear Information System (INIS)

    Mostepanenko, V M

    2009-01-01

    Several problems at the interface between the field-theoretical description of the Casimir effect and experiments on measuring the Casimir force are discussed. One of these problems is connected with the definition of the Casimir free energy in ideal metal rectangular boxes satisfying the general physical requirements. It is shown that the consideration of rectangular boxes with a partition (piston) does not negate the previously known results obtained for boxes without a piston. Both sets of results are found to be in mutual agreement. Another problem is related to the use of the proximity force approximation for the interpretation of the experimental data and to the search of analytical results beyond the PFA based on the first principles of quantum field theory. Next, we discuss concepts of experimental precision and of the measure of agreement between experiment and theory. The fundamental difference between these two concepts is clarified. Finally, recent approach to the thermal Casimir force taking screening effects into account is applied to real metals. It is shown that this approach is thermodynamically and experimentally inconsistent. The physical reasons of this inconsistency are connected with the violation of thermal equilibrium which is the basic applicability condition of the Lifshitz theory.

  19. Thermofield dynamics and Casimir effect for fermions

    International Nuclear Information System (INIS)

    Queiroz, H.; Silva, J.C. da; Khanna, F.C.; Malbouisson, J.M.C.; Revzen, M.; Santana, A.E.

    2005-01-01

    A generalization of the Bogoliubov transformation is developed to describe a space compactified fermionic field. The method is the fermionic counterpart of the formalism introduced earlier for bosons [Phys. Rev. A 66 (2002) 052101], and is based on the thermofield dynamics approach. We analyze the energy-momentum tensor for the Casimir effect of a free massless fermion field in a d-dimensional box at finite temperature. As a particular case the Casimir energy and pressure for the field confined in a three-dimensional parallelepiped box are calculated. It is found that the attractive or repulsive nature of the Casimir pressure on opposite faces changes depending on the relative magnitude of the edges. We also determine the temperature at which the Casimir pressure in a cubic box changes sign and estimate its value when the edge of the cube is of the order of the confining lengths for baryons

  20. Casimir Effect on the Worldline

    CERN Document Server

    Gies, Holger; Moyaerts, L; Gies, Holger; Langfeld, Kurt; Moyaerts, Laurent

    2003-01-01

    We develop a method to compute the Casimir effect for arbitrary geometries. The method is based on the string-inspired worldline approach to quantum field theory and its numerical realization with Monte-Carlo techniques. Concentrating on Casimir forces between rigid bodies induced by a fluctuating scalar field, we test our method with the parallel-plate configuration. For the experimentally relevant sphere-plate configuration, we study curvature effects quantitatively and perform a comparison with the ``proximity force approximation'', which is the standard approximation technique. Sizable curvature effects are found for a distance-to-curvature-radius ratio of a/R >~ 0.02. Our method is embedded in renormalizable quantum field theory with a controlled treatment of the UV divergencies. As a technical by-product, we develop various efficient algorithms for generating closed-loop ensembles with Gaussian distribution.

  1. The Casimir effect for pistons with transmittal boundary conditions

    Science.gov (United States)

    Fucci, Guglielmo

    2017-11-01

    This work focuses on the analysis of the Casimir effect for pistons subject to transmittal boundary conditions. In particular we consider, as piston configuration, a direct product manifold of the type I × N where I is a closed interval of the real line and N is a smooth compact Riemannian manifold. By utilizing the spectral zeta function regularization technique, we compute the Casimir energy of the system and the Casimir force acting on the piston. Explicit results for the force are provided when the manifold N is a d-dimensional sphere.

  2. Optical and Casimir effects in topological materials

    Science.gov (United States)

    Wilson, Justin H.

    Two major electromagnetic phenomena, magneto-optical effects and the Casimir effect, have seen much theoretical and experimental use for many years. On the other hand, recently there has been an explosion of theoretical and experimental work on so-called topological materials, and a natural question to ask is how such electromagnetic phenomena change with these novel materials. Specifically, we will consider are topological insulators and Weyl semimetals. When Dirac electrons on the surface of a topological insulator are gapped or Weyl fermions in the bulk of a Weyl semimetal appear due to time-reversal symmetry breaking, there is a resulting quantum anomalous Hall effect (2D in one case and bulk 3D in the other, respectively). For topological insulators, we investigate the role of localized in-gap states which can leave their own fingerprints on the magneto-optics and can therefore be probed. We have shown that these states resonantly contribute to the Hall conductivity and are magneto-optically active. For Weyl semimetals we investigate the Casimir force and show that with thickness, chemical potential, and magnetic field, a repulsive and tunable Casimir force can be obtained. Additionally, various values of the parameters can give various combinations of traps and antitraps. We additionally probe the topological transition called a Lifshitz transition in the band structure of a material and show that in a Casimir experiment, one can observe a non-analytic "kink'' in the Casimir force across such a transition. The material we propose is a spin-orbit coupled semiconductor with large g-factor that can be magnetically tuned through such a transition. Additionally, we propose an experiment with a two-dimensional metal where weak localization is tuned with an applied field in order to definitively test the effect of diffusive electrons on the Casimir force---an issue that is surprisingly unresolved to this day. Lastly, we show how the time-continuous coherent state

  3. A remembrance of Hendrik Casimir in the 60th anniversary of his discovery, with some basic considerations on the Casimir effect

    International Nuclear Information System (INIS)

    Elizalde, Emilio

    2009-01-01

    When the number and importance of the applications of the Casimir effect are flourishing, and on the occasion of the 60th anniversary of his beautiful discovery, as a tribute to the memory of Hendrik Brugt Gerhard Casimir I discuss here some fundamental issues related with the effect that need to be recalled from time to time, as well as on some of my personal impressions of Prof. Casimir. This article may also serve as an easy introduction for the non-specialist willing to learn something about the quantum vacuum.

  4. Evanescent radiation, quantum mechanics and the Casimir effect

    Science.gov (United States)

    Schatten, Kenneth H.

    1989-01-01

    An attempt to bridge the gap between classical and quantum mechanics and to explain the Casimir effect is presented. The general nature of chaotic motion is discussed from two points of view: the first uses catastrophe theory and strange attractors to describe the deterministic view of this motion; the underlying framework for chaos in these classical dynamic systems is their extreme sensitivity to initial conditions. The second interpretation refers to randomness associated with probabilistic dynamics, as for Brownian motion. The present approach to understanding evanescent radiation and its relation to the Casimir effect corresponds to the first interpretation, whereas stochastic electrodynamics corresponds to the second viewpoint. The nonlinear behavior of the electromagnetic field is also studied. This well-understood behavior is utilized to examine the motions of two orbiting charges and shows a closeness between the classical behavior and the quantum uncertainty principle. The evanescent radiation is used to help explain the Casimir effect.

  5. PREFACE: International Workshop '60 Years of the Casimir Effect'

    Science.gov (United States)

    Barton, Gabriel; Carugno, Giovanni; Dodonov, Victor; Man'ko, Margarita

    2009-07-01

    In 1948 Hendrick Casimir published a short article predicting that (neutral) ideal metallic plates attract each other. This attraction is widely ascribed to the quantum vacuum fluctuations of the electromagnetic field (even though away from the limit of ideal metals it depends demonstrably on the physics of the charge carriers vanishing when they cease to carry). Casimir's remarkable discovery, nowadays called the Casimir effect, has charmed several generations of physicists. In the last decade alone, more than a thousand publications have addressed its many consequences, generalizations, and possible applications in different areas from particle physics to cosmology. Interest in the field is still growing driven by impressive progress in experimental skills and its importance for the recently opened-up area of micro- and nano-electromechanical systems: according to the Thompson ISI Web of Science database, in 2005 the number of papers related to the Casimir effect or to Casimir forces jumped to over 125, compared to approximately 60 in 2000 and 30 in 1995. The increase continues, with more than 170 papers in 2008. The International Workshop '60 Years of the Casimir Effect' took place on 23-27June 2008, in Brasilia (Brazil) organized by the International Center for Condensed Matter Physics (ICCMP). The purpose was to celebrate this anniversary of Casimir's pioneering paper by inviting the leading specialists in the area, both theorists and experimentalists, together with young researchers and post-graduate students interested in hearing about the most recent achievements in the field. The Workshop was attended by 65 participants from 14 countries, who presented 41 talks and 12 posters. These Proceedings contain extended versions of almost all the talks and some posters, plus several papers by authors who had planned to attend but for various reasons could not. The contributions are divided (with some inevitable arbitrariness) into four groups. The largest one

  6. Maxwell-Chern-Simons Casimir effect

    International Nuclear Information System (INIS)

    Milton, K.A.; Ng, Y.J.

    1990-01-01

    The topology of (2+1)-dimensional space permits the construction of quantum electrodynamics with the usual Maxwell action augmented by a gauge-invariant, but P- and T-violating, Chern-Simons mass term. We discuss the Casimir effect between parallel lines in such a theory. The effect of finite temperature is also considered. In principle, our results provide a way to measure the topological mass of the photon

  7. Mode Contributions to the Casimir Effect

    Science.gov (United States)

    Intravaia, F.; Henkel, C.

    2010-04-01

    Applying a sum-over-modes approach to the Casimir interaction between two plates with finite conductivity, we isolate and study the contributions of surface plasmons and Foucault (eddy current) modes. We show in particular that for the TE-polarization eddy currents provide a repulsive force that cancels, at high temperatures, the Casimir free energy calculated with the plasma model.

  8. Interplay between geometry and temperature in the Casimir effect

    Energy Technology Data Exchange (ETDEWEB)

    Weber, Alexej

    2010-06-23

    In this thesis, we investigate the interplay between geometry and temperature in the Casimir effect for the inclined-plates, sphere-plate and cylinder-plate configurations. We use the worldline approach, which combines the string-inspired quantum field theoretical formalism with Monte Carlo techniques. The approach allows the precise computation of Casimir energies in arbitrary geometries. We analyze the dependence of the Casimir energy, force and torque on the separation parameter and temperature T, and find Casimir phenomena which are dominated by long-range fluctuations. We demonstrate that for open geometries, thermal energy densities are typically distributed on scales of thermal wavelengths. As an important consequence, approximation methods for thermal corrections based on local energy-density estimates, such as the proximity-force approximation, are found to become unreliable even at small surface-separations. Whereas the hightemperature behavior is always found to be linear in T, richer power-law behaviors at small temperatures emerge. In particular, thermal forces can develop a non-monotonic behavior. Many novel numerical as well as analytical results are presented. (orig.)

  9. Interplay between geometry and temperature in the Casimir effect

    International Nuclear Information System (INIS)

    Weber, Alexej

    2010-01-01

    In this thesis, we investigate the interplay between geometry and temperature in the Casimir effect for the inclined-plates, sphere-plate and cylinder-plate configurations. We use the worldline approach, which combines the string-inspired quantum field theoretical formalism with Monte Carlo techniques. The approach allows the precise computation of Casimir energies in arbitrary geometries. We analyze the dependence of the Casimir energy, force and torque on the separation parameter and temperature T, and find Casimir phenomena which are dominated by long-range fluctuations. We demonstrate that for open geometries, thermal energy densities are typically distributed on scales of thermal wavelengths. As an important consequence, approximation methods for thermal corrections based on local energy-density estimates, such as the proximity-force approximation, are found to become unreliable even at small surface-separations. Whereas the hightemperature behavior is always found to be linear in T, richer power-law behaviors at small temperatures emerge. In particular, thermal forces can develop a non-monotonic behavior. Many novel numerical as well as analytical results are presented. (orig.)

  10. Casimir stress in an inhomogeneous medium

    International Nuclear Information System (INIS)

    Philbin, T.G.; Xiong, C.; Leonhardt, U.

    2010-01-01

    The Casimir effect in an inhomogeneous dielectric is investigated using Lifshitz's theory of electromagnetic vacuum energy. A permittivity function that depends continuously on one Cartesian coordinate is chosen, bounded on each side by homogeneous dielectrics. The result for the Casimir stress is infinite everywhere inside the inhomogeneous region, a divergence that does not occur for piece-wise homogeneous dielectrics with planar boundaries. A Casimir force per unit volume can be extracted from the infinite stress but it diverges on the boundaries between the inhomogeneous medium and the homogeneous dielectrics. An alternative regularization of the vacuum stress is considered that removes the contribution of the inhomogeneity over small distances, where macroscopic electromagnetism is invalid. The alternative regularization yields a finite Casimir stress inside the inhomogeneous region, but the stress and force per unit volume diverge on the boundaries with the homogeneous dielectrics. The case of inhomogeneous dielectrics with planar boundaries thus falls outside the current understanding of the Casimir effect.

  11. Standard Model Extension and Casimir effect for fermions at finite temperature

    Energy Technology Data Exchange (ETDEWEB)

    Santos, A.F., E-mail: alesandroferreira@fisica.ufmt.br [Instituto de Física, Universidade Federal de Mato Grosso, 78060-900, Cuiabá, Mato Grosso (Brazil); Department of Physics and Astronomy, University of Victoria, 3800 Finnerty Road, Victoria, BC (Canada); Khanna, Faqir C., E-mail: khannaf@uvic.ca [Department of Physics and Astronomy, University of Victoria, 3800 Finnerty Road, Victoria, BC (Canada); Department of Physics, University of Alberta, T6J 2J1, Edmonton, Alberta (Canada)

    2016-11-10

    Lorentz and CPT symmetries are foundations for important processes in particle physics. Recent studies in Standard Model Extension (SME) at high energy indicate that these symmetries may be violated. Modifications in the lagrangian are necessary to achieve a hermitian hamiltonian. The fermion sector of the standard model extension is used to calculate the effects of the Lorentz and CPT violation on the Casimir effect at zero and finite temperature. The Casimir effect and Stefan–Boltzmann law at finite temperature are calculated using the thermo field dynamics formalism.

  12. CasimirSim - A Tool to Compute Casimir Polder Forces for Nontrivial 3D Geometries

    International Nuclear Information System (INIS)

    Sedmik, Rene; Tajmar, Martin

    2007-01-01

    The so-called Casimir effect is one of the most interesting macro-quantum effects. Being negligible on the macro-scale it becomes a governing factor below structure sizes of 1 μm where it accounts for typically 100 kN m-2. The force does not depend on gravity, or electric charge but solely on the materials properties, and geometrical shape. This makes the effect a strong candidate for micro(nano)-mechanical devices M(N)EMS. Despite a long history of research the theory lacks a uniform description valid for arbitrary geometries which retards technical application. We present an advanced state-of-the-art numerical tool overcoming all the usual geometrical restrictions, capable of calculating arbitrary 3D geometries by utilizing the Casimir Polder approximation for the Casimir force

  13. Detecting Casimir torque with an optically levitated nanorod

    Science.gov (United States)

    Xu, Zhujing; Li, Tongcang

    2017-09-01

    The linear momentum and angular momentum of virtual photons of quantum vacuum fluctuations can induce the Casimir force and the Casimir torque, respectively. While the Casimir force has been measured extensively, the Casimir torque has not been observed experimentally though it was predicted over 40 years ago. Here we propose to detect the Casimir torque with an optically levitated nanorod near a birefringent plate in vacuum. The axis of the nanorod tends to align with the polarization direction of the linearly polarized optical tweezer. When its axis is not parallel or perpendicular to the optical axis of the birefringent crystal, it will experience a Casimir torque that shifts its orientation slightly. We calculate the Casimir torque and Casimir force acting on a levitated nanorod near a birefringent crystal. We also investigate the effects of thermal noise and photon recoils on the torque and force detection. We prove that a levitated nanorod in vacuum will be capable of detecting the Casimir torque under realistic conditions, and will be an important tool in precision measurements.

  14. Vector Casimir effect for a D-dimensional sphere

    International Nuclear Information System (INIS)

    Milton, K.A.

    1997-01-01

    The Casimir energy or stress due to modes in a D-dimensional volume subject to TM (mixed) boundary conditions on a bounding spherical surface is calculated. Both interior and exterior modes are included. Together with earlier results found for scalar modes (TE modes), this gives the Casimir effect for fluctuating open-quotes electromagneticclose quotes (vector) fields inside and outside a spherical shell. Known results for three dimensions, first found by Boyer, are reproduced. Qualitatively, the results for TM modes are similar to those for scalar modes: Poles occur in the stress at positive even dimensions, and cusps (logarithmic singularities) occur for integer dimensions D≤1. Particular attention is given the interesting case of D=2. copyright 1997 The American Physical Society

  15. Scalar Casimir effect for a D-dimensional sphere

    International Nuclear Information System (INIS)

    Bender, C.M.; Milton, K.A.

    1994-01-01

    The Casimir stress on a D-dimensional sphere (the stress on a sphere is equal to the Casimir force per unit area multiplied by the area of the sphere) due to the confinement of a massless scalar field is computed as a function of D, where D is a continuous variable that ranges from -∞ to ∞. The dependence of the stress on the dimension is obtained using a simple and straightforward Green's function technique. We find that the Casimir stress vanishes as D→+∞ (D is a noneven integer) and also vanishes when D is a negative even integer. The stress has simple poles at positive even integer values of D

  16. Casimir stress inside planar materials

    Science.gov (United States)

    Griniasty, Itay; Leonhardt, Ulf

    2017-09-01

    The Casimir force between macroscopic bodies is well understood, but not the Casimir force inside bodies. Guided by a physically intuitive picture, we develop the macroscopic theory of the renormalized Casimir stress inside planar materials (where the electromagnetic properties vary in one direction). Our theory may be applied in predicting how inhomogeneous fluids respond to Casimir forces.

  17. Repulsive Casimir force in Bose–Einstein Condensate

    Science.gov (United States)

    Mehedi Faruk, Mir; Biswas, Shovon

    2018-04-01

    We study the Casimir effect for a three dimensional system of ideal free massive Bose gas in a slab geometry with Zaremba and anti-periodic boundary conditions. It is found that for these type of boundary conditions the resulting Casimir force is repulsive in nature, in contrast with usual periodic, Dirichlet or Neumann boundary condition where the Casimir force is attractive (Martin and Zagrebnov 2006 Europhys. Lett. 73 15). Casimir forces in these boundary conditions also maintain a power law decay function below condensation temperature and exponential decay function above the condensation temperature albeit with a positive sign, identifying the repulsive nature of the force.

  18. Stronger constraints on non-Newtonian gravity from the Casimir effect

    Energy Technology Data Exchange (ETDEWEB)

    Mostepanenko, V M; Klimchitskaya, G L [Center of Theoretical Studies and Institute for Theoretical Physics, Leipzig University, D-04009, Leipzig (Germany); Decca, R S [Department of Physics, Indiana University-Purdue University Indianapolis, Indianapolis, IN 46202 (United States); Fischbach, E; Krause, D E [Department of Physics, Purdue University, West Lafayette, IN 47907 (United States); Lopez, D [Bell Laboratories, Lucent Technologies, Murray Hill, NJ 07974 (United States)

    2008-04-25

    We review new constraints on the Yukawa-type corrections to Newtonian gravity obtained recently from gravitational experiments and from the measurements of the Casimir force. Special attention is paid to the constraints following from the most precise dynamic determination of the Casimir pressure between the two parallel plates by means of a micromechanical torsional oscillator. The possibility of setting limits on the predictions of chameleon field theories using the results of gravitational experiments and Casimir force measurements is discussed.

  19. Three-dimensional Casimir piston for massive scalar fields

    International Nuclear Information System (INIS)

    Lim, S.C.; Teo, L.P.

    2009-01-01

    We consider Casimir force acting on a three-dimensional rectangular piston due to a massive scalar field subject to periodic, Dirichlet and Neumann boundary conditions. Exponential cut-off method is used to derive the Casimir energy. It is shown that the divergent terms do not contribute to the Casimir force acting on the piston, thus render a finite well-defined Casimir force acting on the piston. Explicit expressions for the total Casimir force acting on the piston is derived, which show that the Casimir force is always attractive for all the different boundary conditions considered. As a function of a - the distance from the piston to the opposite wall, it is found that the magnitude of the Casimir force behaves like 1/a 4 when a→0 + and decays exponentially when a→∞. Moreover, the magnitude of the Casimir force is always a decreasing function of a. On the other hand, passing from massless to massive, we find that the effect of the mass is insignificant when a is small, but the magnitude of the force is decreased for large a in the massive case.

  20. Implications of the Babinet Principle for Casimir interactions

    International Nuclear Information System (INIS)

    Maghrebi, Mohammad F.; Jaffe, Robert L.; Abravanel, Ronen

    2011-01-01

    We formulate the Babinet Principle (BP) as a relation between scattering amplitudes and combine it with multiple scattering techniques to derive new properties of electromagnetic Casimir forces. We show that the Casimir force exerted by a planar conductor or dielectric on a self-complementary perforated planar mirror is approximately half that on a uniform mirror independent of the distance between them. Also, the BP suggests that Casimir edge effects are generically anomalously small. Furthermore, the BP can be used to relate any planar object to its complementary geometry, a relation we use to estimate Casimir forces between two screens with apertures.

  1. Implications of the Babinet Principle for Casimir interactions

    Science.gov (United States)

    Maghrebi, Mohammad F.; Jaffe, Robert L.; Abravanel, Ronen

    2011-09-01

    We formulate the Babinet Principle (BP) as a relation between scattering amplitudes and combine it with multiple scattering techniques to derive new properties of electromagnetic Casimir forces. We show that the Casimir force exerted by a planar conductor or dielectric on a self-complementary perforated planar mirror is approximately half that on a uniform mirror independent of the distance between them. Also, the BP suggests that Casimir edge effects are generically anomalously small. Furthermore, the BP can be used to relate any planar object to its complementary geometry, a relation we use to estimate Casimir forces between two screens with apertures.

  2. Casimir effect in a d-dimensional flat spacetime and the cut-off method

    International Nuclear Information System (INIS)

    Svaiter, N.F.; Svaiter, B.F.

    1989-01-01

    The CasiMir efeect in a D-dimensional spacetime produced by a Hermitian massless scalar field in the presence of a pair of perfectly reflecting parallel flat plates is discussed. The exponential cut-off regularization method is employed. The regularized vacuum energy and the Casimir energy of this field are evaluated and a detailed analysis of the divergent terms in the regularized vacuum energy is carried out. The two-dimensional version of the Casimir effect is discussed by means of the same cut-off method. A comparison between the above method and the zeta function regularization procedure is presented in a way which gives the unification between these two methods in the present case. (author) [pt

  3. The Casimir Effect Upon A Single Plate

    OpenAIRE

    Hoodbhoy, Pervez

    2004-01-01

    In the presence of an external field, the imposition of specific boundary conditions can lead to interesting new manifestations of the Casimir effect. In particular, it is shown here that even a single conducting plate may experience a non-zero force due to vacuum fluctuations. The origins of this force lie in the change induced by the external potential in the density of available quantum states.

  4. Casimir forces and geometry

    International Nuclear Information System (INIS)

    Buescher, R.

    2005-01-01

    Casimir interactions are interactions induced by quantum vacuum fluctuations and thermal fluctuations of the electromagnetic field. Using a path integral quantization for the gauge field, an effective Gaussian action will be derived which is the starting point to compute Casimir forces between macroscopic objects analytically and numerically. No assumptions about the independence of the material and shape dependent contributions to the interaction are made. We study the limit of flat surfaces in further detail and obtain a concise derivation of Lifshitz' theory of molecular forces. For the case of ideally conducting boundaries, the Gaussian action will be calculated explicitly. Both limiting cases are also discussed within the framework of a scalar field quantization approach, which is applicable for translationally invariant geometries. We develop a non-perturbative approach to calculate the Casimir interaction from the Gaussian action for periodically deformed and ideally conducting objects numerically. The obtained results reveal two different scaling regimes for the Casimir force as a function of the distance between the objects, their deformation wavelength and -amplitude. The results confirm that the interaction is non-additive, especially in the presence of strong geometric deformations. Furthermore, the numerical approach is extended to calculate lateral Casimir forces. The results are consistent with the results of the proximity-force approximation for large deformation wavelengths. A qualitatively different behaviour between the normal and lateral force is revealed. We also establish a relation between the boundary induced change of the of the density of states for the scalar Helmholtz equation and the Casimir interaction using the path integral method. For statically deformed boundaries, this relation can be expressed as a novel trace formula, which is formally similar to the so-called Krein-Friedel-Lloyd formula. While the latter formula describes the

  5. Casimir force in the presence of a medium

    International Nuclear Information System (INIS)

    Kheirandish, Fardin; Soltani, Morteza; Sarabadani, Jalal

    2010-01-01

    We investigate the Casimir effect in the presence of a medium by quantizing the electromagnetic field in the presence of a magnetodielectric medium using the path-integral technique. For a given medium with definite electric and magnetic susceptibilities, explicit expressions for the Casimir force are obtained. The Lifshitz formula is recovered and in the absence of a medium the results tend to the original Casimir force between two conducting parallel plates immersed in the quantum electromagnetic vacuum.

  6. Dynamical Casimir effect on a cavity with mixed boundary conditions

    International Nuclear Information System (INIS)

    Alves, Danilo T.; Farina, Carlos; Maia Neto, Paulo Americo

    2002-01-01

    The most well-known mechanical effect related to the quantum vacuum is the Casimir force between two mirrors at rest. A new effect appears when the mirrors are set to move. In this case, the vacuum field may exert a dissipative force, damping the motion. As a consequence of energy conservation, there will be creation of real particles. If the motion is non-relativistic and has a small amplitude, the dynamical Casimir force can be found via a perturbative method proposed by Ford and Vilenkin. Using their technique, the electromagnetic dynamical Casimir problem, considered when the oscillating cavity is formed by two parallel plates of the same nature (perfectly conducting or perfectly permeable), can be divided into two separated boundary condition problems, namely: one involving Dirichlet BC, related to the transverse electric polarization and the other involving a Neumann BC, related to the transverse magnetic mode. The case of conducting plates can be found in the literature. However, another interesting case, the mixed oscillating cavity where the plates are of different nature, namely, a perfectly conducting plate and a perfectly permeable one (Boyer plates), has not been studied yet. We show that,for this case, the transverse electric models will be related to mixed boundary conditions: Dirichlet-like BC at the conducting plate and Neumann-like BC at the permeable plate. Analogously, the magnetic modes are related to a Neumann BC at the conducting plate and to a Dirichlet BC at the permeable one. As a first step before attacking the three-dimensional electromagnetic problem with mixed BC, we present here a simpler model: a one-dimensional cavity, where a massless scalar field is submitted to mixed (Dirichlet-Neumann) BC. For simplicity, we consider a non-relativistic motion for the conducting wall (Dirichlet BC) and suppose that the perfectly permeable wall (Neumann BC) is at rest. From this model we can extract insights about the dynamical Casimir

  7. Nonlinear (Anharmonic Casimir Oscillator

    Directory of Open Access Journals (Sweden)

    Habibollah Razmi

    2011-01-01

    Full Text Available We want to study the dynamics of a simple linear harmonic micro spring which is under the influence of the quantum Casimir force/pressure and thus behaves as a (an nonlinear (anharmonic Casimir oscillator. Generally, the equation of motion of this nonlinear micromechanical Casimir oscillator has no exact solvable (analytical solution and the turning point(s of the system has (have no fixed position(s; however, for particular values of the stiffness of the micro spring and at appropriately well-chosen distance scales and conditions, there is (are approximately sinusoidal solution(s for the problem (the variable turning points are collected in a very small interval of positions. This, as a simple and elementary plan, may be useful in controlling the Casimir stiction problem in micromechanical devices.

  8. Casimir-type effects for scalar fields interacting with material slabs

    International Nuclear Information System (INIS)

    Fialkovsky, I V; Pis'mak, Yu M; Markov, V N

    2010-01-01

    We study the field theoretical model of a scalar field in the presence of spacial inhomogeneities in the form of one and two finite-width mirrors (material slabs). The interaction of the scalar field with the defect is described with a position-dependent mass term. For a single-layer system we develop a rigorous calculation method and derive explicitly the propagator of the theory, the S-matrix elements and the Casimir self-energy of the slab. Detailed investigation of particular limits of self-energy is presented, and the connection to known cases is discussed. The calculation method is also found applicable to the two-mirror case. With its help we derive the corresponding Casimir energy and analyze it. For particular values of parameters of the model an obtained result recovers the Lifshitz formula. We also propose a procedure to unambiguously obtain the finite Casimir self-energy of a single slab without reference to any renormalization conditions. We hope that our approach can be applied to the calculation of Casimir self-energies in other demanded cases (such as a dielectric ball, etc).

  9. Theoretical modeling of the effect of Casimir attraction on the electrostatic instability of nanowire-fabricated actuators

    Science.gov (United States)

    Mokhtari, J.; Farrokhabadi, A.; Rach, R.; Abadyan, M.

    2015-04-01

    The presence of the quantum vacuum fluctuations, i.e. the Casimir attraction, can strongly affect the performance of ultra-small actuators. The strength of the Casimir force is significantly influenced by the geometries of interacting bodies. Previous research has exclusively studied the impact of the vacuum fluctuations on the instability of nanoactuators with planar geometries. However, no work has yet considered this phenomenon in actuators fabricated from nanowires/nanotubes with cylindrical geometries. In our present work, the influence of the Casimir attraction on the electrostatic stability of nanoactuators fabricated from cylindrical conductive nanowire/nanotube is investigated. The Dirichlet mode is considered and an asymptotic solution, based on scattering theory, is applied to consider the effect of vacuum fluctuations in the theoretical model. The size-dependent modified couple stress theory is employed to derive the constitutive equation of the actuator. The governing nonlinear equations are solved by two different approaches, i.e. the finite difference method and modified Adomian-Padé method. Various aspects of the problem, i.e. comparison with the van der Waals force regime, the variation of instability parameters, effect of geometry and coupling between the Casimir force and size dependency are discussed. This work is beneficial to determine the impact of Casimir force on nanowire/nanotube-fabricated actuators.

  10. Vortex loops in the critical Casimir effect in superfluid and superconducting films

    International Nuclear Information System (INIS)

    Williams, Gary A.

    2004-01-01

    Vortex-loop renormalization techniques are used to calculate the magnitude of the critical Casimir forces in superfluid and superconducting thin films. The force is found to become appreciable when the size of the thermally excited vortex loops is comparable to the film thickness, and the results for T c are found to match very well with perturbative renormalization-group theories that can only be carried out for T>T c . In helium films the Casimir force leads to a change in the film thickness close to T c that has been observed experimentally. A similar effect is predicted to occur near the transition temperature of high-T c superconducting films, which is also a vortex-loop phase transition. In this case the Casimir force takes the form of a voltage difference that will appear at the junction between a thin film and a bulk sample. Estimates show that this voltage can be appreciable (tens of microvolts), and it may be possible to observe the effect by measuring the voltage across two Josephson tunnel junctions to the film and to the bulk, using a SQUID voltmeter

  11. Casimir effect in hyperbolic polygons

    International Nuclear Information System (INIS)

    Ahmedov, H

    2007-01-01

    Using the point splitting regularization method and the trace formula for the spectra of quantum-mechanical systems in hyperbolic polygons which are the fundamental domains of discrete isometry groups acting in the two-dimensional hyperboloid we calculate the Casimir energy for massless scalar fields in hyperbolic polygons. The dependence of the vacuum energy on the number of vertices is established

  12. Precision measurement of the Casimir-Lifshitz force in a fluid

    International Nuclear Information System (INIS)

    Munday, J. N.; Capasso, Federico

    2007-01-01

    The Casimir force, which results from the confinement of the quantum-mechanical zero-point fluctuations of electromagnetic fields, has received significant attention in recent years for its effect on micro- and nanoscale mechanical systems. With few exceptions, experimental observations have been limited to interacting conductive bodies separated by vacuum or air. However, interesting phenomena, including repulsive forces, are expected to exist in certain circumstances between metals and dielectrics when the intervening medium is not vacuum. In order to better understand the effect of the Casimir force in such situations and to test the robustness of the generalized Casimir-Lifshitz theory, we have performed precision measurements of the Casimir force between two metals immersed in a fluid. For this situation, the measured force is attractive and is approximately 80% smaller than the force predicted by Casimir for ideal metals in vacuum. We present experimental results and find them to be consistent with Lifshitz's theory

  13. The Casimir effect as a candidate of dark energy

    OpenAIRE

    Matsumoto, Jiro

    2013-01-01

    It is known that the simply evaluated value of the zero point energy of quantum fields is extremely deviated from the observed value of dark energy density. In this paper, we consider whether the Casimir energy, which is the zero point energy brought from boundary conditions, can cause the accelerating expansion of the Universe by using proper renormalization method and introducing the fermions of finite temperature living in $3+n+1$ space-time. We show that the zero temperature Casimir energ...

  14. Calculating Casimir energies in renormalizable quantum field theory

    International Nuclear Information System (INIS)

    Milton, Kimball A.

    2003-01-01

    Quantum vacuum energy has been known to have observable consequences since 1948 when Casimir calculated the force of attraction between parallel uncharged plates, a phenomenon confirmed experimentally with ever increasing precision. Casimir himself suggested that a similar attractive self-stress existed for a conducting spherical shell, but Boyer obtained a repulsive stress. Other geometries and higher dimensions have been considered over the years. Local effects, and divergences associated with surfaces and edges were studied by several authors. Quite recently, Graham et al. have reexamined such calculations, using conventional techniques of perturbative quantum field theory to remove divergences, and have suggested that previous self-stress results may be suspect. Here we show that the examples considered in their work are misleading; in particular, it is well known that in two space dimensions a circular boundary has a divergence in the Casimir energy for massless fields, while for general spatial dimension D not equal to an even integer the corresponding Casimir energy arising from massless fields interior and exterior to a hyperspherical shell is finite. It has also long been recognized that the Casimir energy for massive fields is divergent for curved boundaries. These conclusions are reinforced by a calculation of the relevant leading Feynman diagram in D and in three dimensions. There is therefore no doubt of the validity of the conventional finite Casimir calculations

  15. Finite temperature Casimir effect for a massless fractional Klein-Gordon field with fractional Neumann conditions

    International Nuclear Information System (INIS)

    Eab, C. H.; Lim, S. C.; Teo, L. P.

    2007-01-01

    This paper studies the Casimir effect due to fractional massless Klein-Gordon field confined to parallel plates. A new kind of boundary condition called fractional Neumann condition which involves vanishing fractional derivatives of the field is introduced. The fractional Neumann condition allows the interpolation of Dirichlet and Neumann conditions imposed on the two plates. There exists a transition value in the difference between the orders of the fractional Neumann conditions for which the Casimir force changes from attractive to repulsive. Low and high temperature limits of Casimir energy and pressure are obtained. For sufficiently high temperature, these quantities are dominated by terms independent of the boundary conditions. Finally, validity of the temperature inversion symmetry for various boundary conditions is discussed

  16. Controlling Casimir force via coherent driving field

    Science.gov (United States)

    Ahmad, Rashid; Abbas, Muqaddar; Ahmad, Iftikhar; Qamar, Sajid

    2016-04-01

    A four level atom-field configuration is used to investigate the coherent control of Casimir force between two identical plates made up of chiral atomic media and separated by vacuum of width d. The electromagnetic chirality-induced negative refraction is obtained via atomic coherence. The behavior of Casimir force is investigated using Casimir-Lifshitz formula. It is noticed that Casimir force can be switched from repulsive to attractive and vice versa via coherent control of the driving field. This switching feature provides new possibilities of using the repulsive Casimir force in the development of new emerging technologies, such as, micro-electro-mechanical and nano-electro-mechanical systems, i.e., MEMS and NEMS, respectively.

  17. Casimir-Foucault interaction: Free energy and entropy at low temperature

    Science.gov (United States)

    Intravaia, Francesco; Ellingsen, Simen Å.; Henkel, Carsten

    2010-09-01

    It was recently found that thermodynamic anomalies which arise in the Casimir effect between metals described by the Drude model can be attributed to the interaction of fluctuating Foucault (or eddy) currents [F. Intravaia and C. Henkel, Phys. Rev. Lett.PRLTAO0031-900710.1103/PhysRevLett.103.130405 103, 130405 (2009).] We focus on the transverse electric (TE) polarization, where the anomalies occur, and show explicitly that the two leading terms of the low-temperature correction to the Casimir free energy of interaction between two plates are identical to those pertaining to the Foucault current interaction alone, up to a correction which is very small for good metals. Moreover, a mode density along real frequencies is introduced, showing that the TE contribution to the Casimir free energy, as given by the Lifshitz theory, separates in a natural manner into contributions from eddy currents and propagating cavity modes, respectively. The latter have long been known to be of little importance to the low-temperature Casimir anomalies. This convincingly demonstrates that eddy current modes are responsible for the large temperature correction to the Casimir effect between Drude metals, predicted by the Lifshitz theory, but not observed in experiments.

  18. Casimir-Foucault interaction: Free energy and entropy at low temperature

    International Nuclear Information System (INIS)

    Intravaia, Francesco; Ellingsen, Simen A.; Henkel, Carsten

    2010-01-01

    It was recently found that thermodynamic anomalies which arise in the Casimir effect between metals described by the Drude model can be attributed to the interaction of fluctuating Foucault (or eddy) currents [F. Intravaia and C. Henkel, Phys. Rev. Lett. 103, 130405 (2009).] We focus on the transverse electric (TE) polarization, where the anomalies occur, and show explicitly that the two leading terms of the low-temperature correction to the Casimir free energy of interaction between two plates are identical to those pertaining to the Foucault current interaction alone, up to a correction which is very small for good metals. Moreover, a mode density along real frequencies is introduced, showing that the TE contribution to the Casimir free energy, as given by the Lifshitz theory, separates in a natural manner into contributions from eddy currents and propagating cavity modes, respectively. The latter have long been known to be of little importance to the low-temperature Casimir anomalies. This convincingly demonstrates that eddy current modes are responsible for the large temperature correction to the Casimir effect between Drude metals, predicted by the Lifshitz theory, but not observed in experiments.

  19. Quantum theories on noncommutative spaces with nontrivial topology: Aharonov-Bohm and Casimir effects

    International Nuclear Information System (INIS)

    Chaichian, M.; Tureanu, A.; Demichev, A.; Presnajder, P.; Sheikh-Jabbari, M.M.

    2001-02-01

    After discussing the peculiarities of quantum systems on noncommutative (NC) spaces with nontrivial topology and the operator representation of the *-product on them, we consider the Aharonov-Bohm and Casimir effects for such spaces. For the case of the Aharonov-Bohm effect, we have obtained an explicit expression for the shift of the phase, which is gauge invariant in the NC sense. The Casimir energy of a field theory on a NC cylinder is divergent, while it becomes finite on a torus, when the dimensionless parameter of noncommutativity is a rational number. The latter corresponds to a well-defined physical picture. Certain distinctions from other treatments based on a different way of taking the noncommutativity into account are also discussed. (author)

  20. Casimir-Polder interaction in second quantization

    Energy Technology Data Exchange (ETDEWEB)

    Schiefele, Juergen

    2011-03-21

    The Casimir-Polder interaction between a single neutral atom and a nearby surface, arising from the (quantum and thermal) fluctuations of the electromagnetic field, is a cornerstone of cavity quantum electrodynamics (cQED), and theoretically well established. Recently, Bose-Einstein condensates (BECs) of ultracold atoms have been used to test the predictions of cQED. The purpose of the present thesis is to upgrade single-atom cQED with the many-body theory needed to describe trapped atomic BECs. Tools and methods are developed in a second-quantized picture that treats atom and photon fields on the same footing. We formulate a diagrammatic expansion using correlation functions for both the electromagnetic field and the atomic system. The formalism is applied to investigate, for BECs trapped near surfaces, dispersion interactions of the van der Waals-Casimir-Polder type, and the Bosonic stimulation in spontaneous decay of excited atomic states. We also discuss a phononic Casimir effect, which arises from the quantum fluctuations in an interacting BEC. (orig.)

  1. Casimir-Polder interaction in second quantization

    International Nuclear Information System (INIS)

    Schiefele, Juergen

    2011-01-01

    The Casimir-Polder interaction between a single neutral atom and a nearby surface, arising from the (quantum and thermal) fluctuations of the electromagnetic field, is a cornerstone of cavity quantum electrodynamics (cQED), and theoretically well established. Recently, Bose-Einstein condensates (BECs) of ultracold atoms have been used to test the predictions of cQED. The purpose of the present thesis is to upgrade single-atom cQED with the many-body theory needed to describe trapped atomic BECs. Tools and methods are developed in a second-quantized picture that treats atom and photon fields on the same footing. We formulate a diagrammatic expansion using correlation functions for both the electromagnetic field and the atomic system. The formalism is applied to investigate, for BECs trapped near surfaces, dispersion interactions of the van der Waals-Casimir-Polder type, and the Bosonic stimulation in spontaneous decay of excited atomic states. We also discuss a phononic Casimir effect, which arises from the quantum fluctuations in an interacting BEC. (orig.)

  2. Dispersion forces in micromechanics: Casimir and Casimir-Polder forces affected by geometry and non-zero temperature

    Energy Technology Data Exchange (ETDEWEB)

    Ellingsen, Simen Andreas Aadnoey

    2011-01-15

    The present thesis focuses on several topics within three separate but related branches of the overall field of dispersion forces. The three branches are: temperature corrections to the Casimir force between real materials (Part 1), explicit calculation of Casimir energy in wedge geometries (Part 2), and Casimir-Polder forces on particles out of thermal equilibrium (Part 3). Part 1 deals primarily with analysis of a previously purported thermodynamic inconsistency in the Casimir-Lifshitz free energy of the interaction of two plane mirrors - violation of the third law of thermodynamics - when the latter's dielectric response is described with dissipative models. It is shown analytically and numerically that the Casimir entropy of the interaction between two metallic mirrors described by the Drude model does tend to zero at zero temperature, provided electronic relaxation does not vanish. The leading order terms at low temperature are found. A similar calculation is carried out for the interaction of semiconductors with small but non-zero DC conductivity. In a generalisation, it is shown that a violation of the third law can only occur for permittivities whose low-frequency behaviour is temperature dependent near zero temperature. A calculation using path integral methods shows that the low temperature behaviour of the interaction of fluctuating Foucault currents in two mirrors of Drude metal is identical to that of the full Casimir-Lifshitz free energy, reasserting a previous finding by Intravaia and Henkel that such fluctuating bulk currents are the physical reason for the anomalous entropy behaviour. In a related effort, an analysis of the frequency dependence of the Casimir force by Ford is generalised to imperfectly reflecting mirrors. A paradox is pointed out, in that the effects of a perturbation of the reflecting properties of the mirrors in a finite frequency window can be calculated in two ways giving different results. It is concluded that optimistic

  3. Repulsive Casimir force at zero and finite temperature

    International Nuclear Information System (INIS)

    Lim, S C; Teo, L P

    2009-01-01

    We study the zero and finite temperature Casimir force acting on a perfectly conducting piston with arbitrary cross section moving inside a closed cylinder with infinitely permeable walls. We show that at any temperature, the Casimir force always tends to move the piston away from the walls and toward its equilibrium position. In the case of a rectangular piston, exact expressions for the Casimir force are derived. In the high-temperature regime, we show that the leading term of the Casimir force is linear in temperature and therefore the Casimir force has a classical limit. Due to duality, all these results also hold for an infinitely permeable piston moving inside a closed cylinder with perfectly conducting walls.

  4. Universality for shape dependence of Casimir effects from Weyl anomaly

    Science.gov (United States)

    Miao, Rong-Xin; Chu, Chong-Sun

    2018-03-01

    We reveal elegant relations between the shape dependence of the Casimir effects and Weyl anomaly in boundary conformal field theories (BCFT). We show that for any BCFT which has a description in terms of an effective action, the near boundary divergent behavior of the renormalized stress tensor is completely determined by the central charges of the theory. These relations are verified by free BCFTs. We also test them with holographic models of BCFT and find exact agreement. We propose that these relations between Casimir coefficients and central charges hold for any BCFT. With the holographic models, we reproduce not only the precise form of the near boundary divergent behavior of the stress tensor, but also the surface counter term that is needed to make the total energy finite. As they are proportional to the central charges, the near boundary divergence of the stress tensor must be physical and cannot be dropped by further artificial renormalization. Our results thus provide affirmative support on the physical nature of the divergent energy density near the boundary, whose reality has been a long-standing controversy in the literature.

  5. Casimir effect for a semitransparent wedge and an annular piston

    International Nuclear Information System (INIS)

    Milton, Kimball A.; Wagner, Jef; Kirsten, Klaus

    2009-01-01

    We consider the Casimir energy due to a massless scalar field in a geometry of an infinite wedge closed by a Dirichlet circular cylinder, where the wedge is formed by δ-function potentials, so-called semitransparent boundaries. A finite expression for the Casimir energy corresponding to the arc and the presence of both semitransparent potentials is obtained, from which the torque on the sidewalls can be derived. The most interesting part of the calculation is the nontrivial nature of the angular mode functions. Numerical results are obtained which are closely analogous to those recently found for a magnetodielectric wedge, with the same speed of light on both sides of the wedge boundaries. Alternative methods are developed for annular regions with radial semitransparent potentials, based on reduced Green's functions for the angular dependence, which allows calculations using the multiple-scattering formalism. Numerical results corresponding to the torque on the radial plates are likewise computed, which generalize those for the wedge geometry. Generally useful formulas for calculating Casimir energies in separable geometries are derived.

  6. Sign and other aspects of semiclassical Casimir energies

    International Nuclear Information System (INIS)

    Schaden, Martin

    2006-01-01

    The Casimir energy of a massless scalar field is semiclassically given by contributions due to classical periodic rays. The required subtractions in the spectral density are determined explicitly. The semiclassical Casimir energies so defined coincide with those of zeta function regularization in the cases studied. Poles in the analytic continuation of zeta function regularization are related to nonuniversal subtractions in the spectral density. The sign of the Casimir energy of a scalar field on a smooth manifold is estimated by the sign of the contribution due to the shortest periodic rays only. Demanding continuity of the Casimir energy under small deformations of the manifold, the method is extended to integrable systems. The Casimir energy of a massless scalar field on a manifold with boundaries includes contributions due to periodic rays that lie entirely within the boundaries. These contributions in general depend on the boundary conditions. Although the Casimir energy due to a massless scalar field may be sensitive to the physical dimensions of manifolds with boundary. In favorable cases its sign can, contrary to conventional wisdom, be inferred without calculation of the Casimir energy

  7. On convergence generation in computing the electro-magnetic Casimir force

    International Nuclear Information System (INIS)

    Schuller, F.

    2008-01-01

    We tackle the very fundamental problem of zero-point energy divergence in the context of the Casimir effect. We calculate the Casimir force due to field fluctuations by using standard cavity radiation modes. The validity of convergence generation by means of an exponential energy cut-off factor is discussed in detail. (orig.)

  8. Influence of van-der-Waals like interactions on the thermodynamic Casimir effect; Einfluss van-der-Waals-artiger Wechselwirkungen auf den thermodynamischen Casimir-Effekt

    Energy Technology Data Exchange (ETDEWEB)

    Grueneberg, Daniel

    2008-02-15

    To study how the behavior of the thermodynamic Casimir force changes qualitatively and quantitatively due to the presence of such interactions - compared to systems with purely short-range interactions - is the aim of this work. Considering d-dimensional models belonging to the universality class of the O(n)-symmetrical systems, the thermodynamic Casimir force and its leading corrections are derived for temperatures at and above the transition temperature (T{>=}T{sub c,{infinity}}). The underlying pair potential is assumed to be isotropic and long-ranged, decaying asymptotically proportional to x{sup -(d+{sigma}}{sup )} for large separations x, where the value of the parameter {sigma} is restricted to the interval 2<{sigma}<4. By solving an appropriate spherical model in 2Casimir force and its leading corrections are obtained. To study the case n<{infinity}, which in 2Casimir force and its leading corrections are evaluated to two-loop order. It is shown that both in the spherical model and in the O(n)-symmetrical case with n<{infinity} to two-loop order, the thermodynamic Casimir force in the presence of the long-range interaction decays algebraically {proportional_to}L{sup -(d+{sigma}}{sup )} at fixed temperature T>T{sub c,{infinity}} on sufficiently large length scales. (orig.)

  9. Interplay between geometry and temperature for inclined Casimir plates

    International Nuclear Information System (INIS)

    Weber, Alexej; Gies, Holger

    2009-01-01

    We provide further evidence for the nontrivial interplay between geometry and temperature in the Casimir effect. We investigate the temperature dependence of the Casimir force between an inclined semi-infinite plate above an infinite plate in D dimensions using the worldline formalism. Whereas the high-temperature behavior is always found to be linear in T in accordance with dimensional-reduction arguments, different power-law behaviors at small temperatures emerge. Unlike the case of infinite parallel plates, which shows the well-known T D behavior of the force, we find a T D-1 behavior for inclined plates, and a ∼T D-0.3 behavior for the edge effect in the limit where the plates become parallel. The strongest temperature dependence ∼T D-2 occurs for the Casimir torque of inclined plates. Numerical as well as analytical worldline results are presented.

  10. Casimir effect and thermodynamics of horizon instabilities

    International Nuclear Information System (INIS)

    Hartnoll, Sean A.

    2004-01-01

    We propose a dual thermodynamic description of a classical instability of generalized black hole spacetimes. From a thermodynamic perspective, the instability is due to negative compressibility in regions where the Casimir pressure is large. The argument indicates how the correspondence between thermodynamic and classical instability for horizons may be extended to cases without translational invariance

  11. Casimir energy and the possibility of higher dimensional manipulation

    OpenAIRE

    Obousy, R. K.; Saharian, A. A.

    2009-01-01

    It is well known that the Casimir effect is an excellent candidate for the stabilization of the extra dimensions. It has also been suggested that the Casimir effect in higher dimensions may be the underlying phenomenon that is responsible for the dark energy which is currently driving the accelerated expansion of the universe. In this paper we suggest that, in principle, it may be possible to directly manipulate the size of an extra dimension locally using Standard Model fields in the next ge...

  12. Nanoparticle separation based on size-dependent aggregation of nanoparticles due to the critical Casimir effect.

    Science.gov (United States)

    Guo, Hongyu; Stan, Gheorghe; Liu, Yun

    2018-02-21

    Nanoparticles typically have an inherent wide size distribution that may affect the performance and reliability of many nanomaterials. Because the synthesis and purification of nanoparticles with desirable sizes are crucial to the applications of nanoparticles in various fields including medicine, biology, health care, and energy, there is a great need to search for more efficient and generic methods for size-selective nanoparticle purification/separation. Here we propose and conclusively demonstrate the effectiveness of a size-selective particle purification/separation method based on the critical Casimir force. The critical Casimir force is a generic interaction between colloidal particles near the solvent critical point and has been extensively studied in the past several decades due to its importance in reversibly controlling the aggregation and stability of colloidal particles. Combining multiple experimental techniques, we found that the critical Casimir force-induced aggregation depends on relative particle sizes in a system with larger ones aggregating first and the smaller ones remaining in solution. Based on this observation, a new size-dependent nanoparticle purification/separation method is proposed and demonstrated to be very efficient in purifying commercial silica nanoparticles in the lutidine/water binary solvent. Due to the ubiquity of the critical Casimir force for many colloidal particles in binary solvents, this method might be applicable to many types of colloidal particles.

  13. Casimir energy density for spherical universes in n-dimensional spacetime

    International Nuclear Information System (INIS)

    Oezcan, Mustafa

    2006-01-01

    We consider the Casimir effect for the massless conformal scalar field in an n-dimensional, closed, static universe. We calculate the renormalized vacuum energy density using the covariant point-splitting method, the mode-sum regularization and the renormalized vacuum energy with the zeta-function regularization. We observe that all odd spacetime dimensions give us the zero renormalized vacuum energy density. For even spacetime dimensions the renormalized vacuum energy density oscillates in sign. The result agrees with three regularization techniques. The Casimir energy density for spherical universes in n-dimensional spacetime is regarded as interesting both to understand the correspondence between the sign of the effect and the dimension of manifold in topology and as a key to confirming the Casimir energy for half spherical universes (manifold with boundary) in n-dimensional spacetime

  14. Neumann Casimir effect: A singular boundary-interaction approach

    International Nuclear Information System (INIS)

    Fosco, C.D.; Lombardo, F.C.; Mazzitelli, F.D.

    2010-01-01

    Dirichlet boundary conditions on a surface can be imposed on a scalar field, by coupling it quadratically to a δ-like potential, the strength of which tends to infinity. Neumann conditions, on the other hand, require the introduction of an even more singular term, which renders the reflection and transmission coefficients ill-defined because of UV divergences. We present a possible procedure to tame those divergences, by introducing a minimum length scale, related to the nonzero 'width' of a nonlocal term. We then use this setup to reach (either exact or imperfect) Neumann conditions, by taking the appropriate limits. After defining meaningful reflection coefficients, we calculate the Casimir energies for flat parallel mirrors, presenting also the extension of the procedure to the case of arbitrary surfaces. Finally, we discuss briefly how to generalize the worldline approach to the nonlocal case, what is potentially useful in order to compute Casimir energies in theories containing nonlocal potentials; in particular, those which we use to reproduce Neumann boundary conditions.

  15. Detecting chameleons through Casimir force measurements

    International Nuclear Information System (INIS)

    Brax, Philippe; Bruck, Carsten van de; Davis, Anne-Christine; Shaw, Douglas; Mota, David F.

    2007-01-01

    The best laboratory constraints on strongly coupled chameleon fields come not from tests of gravity per se but from precision measurements of the Casimir force. The chameleonic force between two nearby bodies is more akin to a Casimir-like force than a gravitational one: The chameleon force behaves as an inverse power of the distance of separation between the surfaces of two bodies, just as the Casimir force does. Additionally, experimental tests of gravity often employ a thin metallic sheet to shield electrostatic forces; however, this sheet masks any detectable signal due to the presence of a strongly coupled chameleon field. As a result of this shielding, experiments that are designed to specifically test the behavior of gravity are often unable to place any constraint on chameleon fields with a strong coupling to matter. Casimir force measurements do not employ a physical electrostatic shield and as such are able to put tighter constraints on the properties of chameleons fields with a strong matter coupling than tests of gravity. Motivated by this, we perform a full investigation on the possibility of testing chameleon models with both present and future Casimir experiments. We find that present-day measurements are not able to detect the chameleon. However, future experiments have a strong possibility of detecting or rule out a whole class of chameleon models

  16. Casimir Interaction from Magnetically Coupled Eddy Currents

    Science.gov (United States)

    Intravaia, Francesco; Henkel, Carsten

    2009-09-01

    We study the quantum and thermal fluctuations of eddy (Foucault) currents in thick metallic plates. A Casimir interaction between two plates arises from the coupling via quasistatic magnetic fields. As a function of distance, the relevant eddy current modes cross over from a quantum to a thermal regime. These modes alone reproduce previously discussed thermal anomalies of the electromagnetic Casimir interaction between good conductors. In particular, they provide a physical picture for the Casimir entropy whose nonzero value at zero temperature arises from a correlated, glassy state.

  17. Casimir Energy, Extra Dimensions and Exotic Propulsion

    Science.gov (United States)

    Obousy, R.; Saharian, A.

    It is well known that the Casimir effect is an excellent candidate for the stabilization of the extra dimensions. It has also been suggested that the Casimir effect in higher dimensions may be the underlying phenomenon that is responsible for the dark energy which is currently driving the accelerated expansion of the universe. In this paper we suggest that, in principle, it may be possible to directly manipulate the size of an extra dimension locally using Standard Model fields in the next generation of particle accelerators. This adjustment of the size of the higher dimension could serve as a technological mechanism to locally adjust the dark energy density and change the local expansion of spacetime. This idea holds tantalizing possibilities in the context of exotic spacecraft propulsion.

  18. Casimir force in O(n) systems with a diffuse interface.

    Science.gov (United States)

    Dantchev, Daniel; Grüneberg, Daniel

    2009-04-01

    We study the behavior of the Casimir force in O(n) systems with a diffuse interface and slab geometry infinity;{d-1}xL , where 2system. We consider a system with nearest-neighbor anisotropic interaction constants J_{ parallel} parallel to the film and J_{ perpendicular} across it. We argue that in such an anisotropic system the Casimir force, the free energy, and the helicity modulus will differ from those of the corresponding isotropic system, even at the bulk critical temperature, despite that these systems both belong to the same universality class. We suggest a relation between the scaling functions pertinent to the both systems. Explicit exact analytical results for the scaling functions, as a function of the temperature T , of the free energy density, Casimir force, and the helicity modulus are derived for the n-->infinity limit of O(n) models with antiperiodic boundary conditions applied along the finite dimension L of the film. We observe that the Casimir amplitude Delta_{Casimir}(dmid R:J_{ perpendicular},J_{ parallel}) of the anisotropic d -dimensional system is related to that of the isotropic system Delta_{Casimir}(d) via Delta_{Casimir}(dmid R:J_{ perpendicular},J_{ parallel})=(J_{ perpendicular}J_{ parallel});{(d-1)2}Delta_{Casimir}(d) . For d=3 we derive the exact Casimir amplitude Delta_{Casimir}(3,mid R:J_{ perpendicular},J_{ parallel})=[Cl_{2}(pi3)3-zeta(3)(6pi)](J_{ perpendicular}J_{ parallel}) , as well as the exact scaling functions of the Casimir force and of the helicity modulus Upsilon(T,L) . We obtain that beta_{c}Upsilon(T_{c},L)=(2pi;{2})[Cl_{2}(pi3)3+7zeta(3)(30pi)](J_{ perpendicular}J_{ parallel})L;{-1} , where T_{c} is the critical temperature of the bulk system. We find that the contributions in the excess free energy due to the existence of a diffuse interface result in a repulsive Casimir force in the whole temperature region.

  19. Attractive Casimir effect in an infrared modified gluon bag model

    International Nuclear Information System (INIS)

    Oxman, L.E.; Amaral, R.L.P.G.; Svaiter, N.F.

    2005-01-01

    In this work, we are motivated by previous attempts to derive the vacuum contribution to the bag energy in terms of familiar Casimir energy calculations for spherical geometries. A simple infrared modified model is introduced which allows studying the effects of the analytic structure as well as the geometry in a clear manner. In this context, we show that if a class of infrared vanishing effective gluon propagators is considered, then the renormalized vacuum energy for a spherical bag is attractive, as required by the bag model to adjust hadron spectroscopy

  20. Repulsive Casimir force from fractional Neumann boundary conditions

    International Nuclear Information System (INIS)

    Lim, S.C.; Teo, L.P.

    2009-01-01

    This Letter studies the finite temperature Casimir force acting on a rectangular piston associated with a massless fractional Klein-Gordon field at finite temperature. Dirichlet boundary conditions are imposed on the walls of a d-dimensional rectangular cavity, and a fractional Neumann condition is imposed on the piston that moves freely inside the cavity. The fractional Neumann condition gives an interpolation between the Dirichlet and Neumann conditions, where the Casimir force is known to be always attractive and always repulsive respectively. For the fractional Neumann boundary condition, the attractive or repulsive nature of the Casimir force is governed by the fractional order which takes values from zero (Dirichlet) to one (Neumann). When the fractional order is larger than 1/2, the Casimir force is always repulsive. For some fractional orders that are less than but close to 1/2, it is shown that the Casimir force can be either attractive or repulsive depending on the aspect ratio of the cavity and the temperature.

  1. Casimir interactions for anisotropic magnetodielectric metamaterials

    Energy Technology Data Exchange (ETDEWEB)

    Da Rosa, Felipe S [Los Alamos National Laboratory; Dalvit, Diego A [Los Alamos National Laboratory; Milonni, Peter W [Los Alamos National Laboratory

    2008-01-01

    We extend our previous work on the generalization of the Casimir-Lifshitz theory to treat anisotropic magnetodielectric media, focusing on the forces between metals and magnetodielectric metamaterials and on the possibility of inferring magnetic effects by measurements of these forces.

  2. The Casimir effect physical manifestations of zero-point energy

    CERN Document Server

    Milton, K A

    2001-01-01

    In its simplest manifestation, the Casimir effect is a quantum force of attraction between two parallel uncharged conducting plates. More generally, it refers to the interaction - which may be either attractive or repulsive - between material bodies due to quantum fluctuations in whatever fields are relevant. It is a local version of the van der Waals force between molecules. Its sweep ranges from perhaps its being the origin of the cosmological constant to its being responsible for the confinement of quarks. This monograph develops the theory of such forces, based primarily on physically tran

  3. EDITORIAL: The nonstationary Casimir effect and quantum systems with moving boundaries

    Science.gov (United States)

    Barton, Gabriel; Dodonov, Victor V.; Man'ko, Vladimir I.

    2005-03-01

    This topical issue of Journal of Optics B: Quantum and Semiclassical Optics contains 16 contributions devoted to quantum systems with moving boundaries. In a broad sense, the papers continue the studies opened exactly 100 years ago by Einstein in his seminal work on the electrodynamics of moving bodies and the quantum nature of light. Another jubilee which we wish to celebrate by launching this issue is the 80th anniversary of the publication of two papers, where the first solutions of the classical Maxwell equations in a one-dimensional cavity with moving boundaries were obtained, by T H Havelock (1924 Some dynamical illustrations of the pressure of radiation and of adiabatic invariance Phil. Mag. 47 754-71) and by E L Nicolai (1925 On a dynamical illustration of the pressure of radiation Phil. Mag. 49 171-7). As was shown by Einstein, studying the fluctuations of the electromagnetic field inevitably leads one to its quantum (corpuscular) nature. Many papers in this issue deal with problems where moving boundaries produce parametric excitation of vacuum fluctuations of the field, which could result in several different observable effects, like the modification of the famous Casimir force, or the creation of real quanta from the vacuum. It is worth emphasizing that these phenomena, frequently referred to as nonstationary (or dynamical) Casimir effects, are no longer the province only of pure theorists: some experimental groups have already started long-term work aimed at observing such effects in the laboratory. Of course, many difficult problems remain to be resolved before this dream becomes reality. Several papers here show both important progress in this direction, and possible difficulties still to be tackled. Problems that have been considered include, in particular, decoherence, entanglement, and the roles of geometry and polarization. Other papers deal with fundamental problems like the Unruh effect, the interaction of accelerated relativistic atoms with

  4. Oscillating Casimir force between two slabs in a Fermi sea

    DEFF Research Database (Denmark)

    Li-Wei, Chen; Guo-Zhen, Su; Jin-Can, Chen

    2012-01-01

    that the Casimir force decreases monotonically with the increase of the separation L between two slabs in an electromagnetic field and a massive Bose gas, the Casimir force in a Fermi gas oscillates as a function of L. The Casimir force can be either attractive or repulsive, depending sensitively on the magnitude...... of L. In addition, it is found that the amplitude of the Casimir force in a Fermi gas decreases with the increase of the temperature, which also is contrary to the case in a Bose gas, since the bosonic Casimir force increases linearly with the increase of the temperature in the region T

  5. Casimir-Polder shifts on quantum levitation states

    Science.gov (United States)

    Crépin, P.-P.; Dufour, G.; Guérout, R.; Lambrecht, A.; Reynaud, S.

    2017-03-01

    An ultracold atom above a horizontal mirror experiences quantum reflection from the attractive Casimir-Polder interaction, which holds it against gravity and leads to quantum levitation states. We analyze this system by using a Liouville transformation of the Schrödinger equation and a Langer coordinate adapted to problems with a classical turning point. Reflection on the Casimir-Polder attractive well is replaced by reflection on a repulsive wall, and the problem is then viewed as an ultracold atom trapped inside a cavity with gravity and Casimir-Polder potentials acting, respectively, as top and bottom mirrors. We calculate numerically Casimir-Polder shifts of the energies of the cavity resonances and propose an approximate treatment which is precise enough to discuss spectroscopy experiments aimed at tests of the weak-equivalence principle on antihydrogen. We also discuss the lifetimes by calculating complex energies associated with cavity resonances.

  6. The thermodynamic Casimir effect with symmetry-preserving and symmetry-breaking boundary conditions; Der thermodynamische Casimir-Effekt mit symmetrieerhaltenden und symmetriebrechenden Randbedingungen

    Energy Technology Data Exchange (ETDEWEB)

    Schmidt, Felix

    2014-07-16

    When macroscopic bodies are immersed in fluctuating media, long-range forces between these bodies may occur. The fluctuation's spectrum is modified resulting in a dependence of the system's energy on the separation between the objects, straightforwardly leading to the existence of a force between the bodies. This work is dedicated to the analysis of how boundary conditions affect the thermodynamic Casimir effect where thermal fluctuations near a critical point induce these forces. O(n) symmetric φ 4 theories in d-dimensional slab geometries of thickness L are considered. When symmetry breaking external fields are present as well, the generic boundary conditions of these theories read ∂{sub n}φ-c{sub j}φ=-h{sub j} where the coefficients c{sub j} are surface couplings, serving as linearly extrapolated penetration depths into the surfaces in Landau theory, and h{sub j} are surface fields. The influence of the surface couplings c{sub j} on the Casimir force is investigated by means of the renormalization-group-improved perturbation theory in d=4-ε dimensions to two-loop order at the bulk critical point. Special attention is paid to the case of critical enhancement of the surface interactions which results in the existence of a zero mode leading to a breakdown of the usual loop expansion of the free energy and implicating the emergence of non-integer powers of ε in the ε expansion. These perturbative methods are restricted to the disordered phase with T≥T{sub c,∞}, c{sub j}≥c{sub sp}, and h{sub j}=0. In order to extend the analysis to the whole temperature axis, the exactly treatable limit n → ∞ of the three-dimensional φ 4 model is investigated. A set of self-consistent equations for the free energy is derived that can be solved numerically exact. Considering Dirichlet boundary conditions and vanishing external fields, one finds a temperature dependence of the Casimir force that exhibits the qualitative features of the experimentally

  7. Controlling the Casimir force via the electromagnetic properties of materials

    International Nuclear Information System (INIS)

    Yang Yaping; Chen Hong; Zeng Ran; Zhu Shiyao; Zubairy, M. Suhail

    2010-01-01

    The control of the Casimir force between two parallel plates can be achieved through adjusting the frequency-dependent electromagnetic properties of materials of the two plates. We show that, for different plate separations, the main contribution to the Casimir force comes from different frequency regions: For smaller (larger) separation, it comes from the higher (lower) frequency region. When the separation of the plates increases, the Casimir force can vary from attractive to repulsive and/or vice versa, by selecting the two plates with suitable electromagnetic properties. We discuss how a restoring Casimir force, which varies from repulsive to attractive by increasing the separation, can be realized and that the stable equilibrium is formed at zero Casimir force.

  8. Nonmonotonic Thermal Casimir Force from Geometry-Temperature Interplay

    International Nuclear Information System (INIS)

    Weber, Alexej; Gies, Holger

    2010-01-01

    The geometry dependence of Casimir forces is significantly more pronounced in the presence of thermal fluctuations due to a generic geometry-temperature interplay. We show that the thermal force for standard sphere-plate or cylinder-plate geometries develops a nonmonotonic behavior already in the simple case of a fluctuating Dirichlet scalar. In particular, the attractive thermal force can increase for increasing distances below a critical temperature. This anomalous behavior is triggered by a reweighting of relevant fluctuations on the scale of the thermal wavelength. The essence of the phenomenon becomes transparent within the worldline picture of the Casimir effect.

  9. Casimir energy of a BEC: from moderate interactions to the ideal gas

    International Nuclear Information System (INIS)

    Schiefele, J; Henkel, C

    2009-01-01

    Considering the Casimir effect due to phononic excitations of a weakly interacting dilute Bose-Einstein condensate (BEC), we derive a renormalized expression for the zero-temperature Casimir energy E C of a BEC confined to a parallel plate geometry with periodic boundary conditions. Our expression is formally equivalent to the free energy of a bosonic field at finite temperature, with a nontrivial density of modes that we compute analytically. As a function of the interaction strength, E C smoothly describes the transition from the weakly interacting Bogoliubov regime to the non-interacting ideal BEC. For the weakly interacting case, E C reduces to leading order to the Casimir energy due to zero-point fluctuations of massless phonon modes. In the limit of an ideal Bose gas, our result correctly describes the Casimir energy going to zero

  10. Scattering theory approach to electrodynamic Casimir forces

    International Nuclear Information System (INIS)

    Rahi, Sahand Jamal; Kardar, Mehran; Emig, Thorsten; Graham, Noah; Jaffe, Robert L.

    2009-01-01

    We give a comprehensive presentation of methods for calculating the Casimir force to arbitrary accuracy, for any number of objects, arbitrary shapes, susceptibility functions, and separations. The technique is applicable to objects immersed in media other than vacuum, nonzero temperatures, and spatial arrangements in which one object is enclosed in another. Our method combines each object's classical electromagnetic scattering amplitude with universal translation matrices, which convert between the bases used to calculate scattering for each object, but are otherwise independent of the details of the individual objects. The method is illustrated by rederiving the Lifshitz formula for infinite half-spaces, by demonstrating the Casimir-Polder to van der Waals crossover, and by computing the Casimir interaction energy of two infinite, parallel, perfect metal cylinders either inside or outside one another. Furthermore, it is used to obtain new results, namely, the Casimir energies of a sphere or a cylinder opposite a plate, all with finite permittivity and permeability, to leading order at large separation.

  11. Graphene cantilever under Casimir force

    Science.gov (United States)

    Derras-Chouk, Amel; Chudnovsky, Eugene M.; Garanin, Dmitry A.; Jaafar, Reem

    2018-05-01

    The stability of graphene cantilever under Casimir attraction to an underlying conductor is investigated. The dependence of the instability threshold on temperature and flexural rigidity is obtained. Analytical work is supplemented by numerical computation of the critical temperature above which the graphene cantilever irreversibly bends down and attaches to the conductor. The geometry of the attachment and exfoliation of the graphene sheet is discussed. It is argued that graphene cantilever can be an excellent tool for precision measurements of the Casimir force.

  12. Fermionic Casimir effect for parallel plates in the presence of compact dimensions with applications to nanotubes

    International Nuclear Information System (INIS)

    Bellucci, S.; Saharian, A. A.

    2009-01-01

    We evaluate the Casimir energy and force for a massive fermionic field in the geometry of two parallel plates on background of Minkowski spacetime with an arbitrary number of toroidally compactified spatial dimensions. The bag boundary conditions are imposed on the plates and periodicity conditions with arbitrary phases are considered along the compact dimensions. The Casimir energy is decomposed into purely topological, single plate and interaction parts. With independence of the lengths of the compact dimensions and the phases in the periodicity conditions, the interaction part of the Casimir energy is always negative. In order to obtain the resulting force, the contributions from both sides of the plates must be taken into account. Then, the forces coming from the topological parts of the vacuum energy cancel out and only the interaction term contributes to the Casimir force. Applications of the general formulae to Kaluza-Klein-type models and carbon nanotubes are given. In particular, we show that for finite-length metallic nanotubes, the Casimir forces acting on the tube edges are always attractive, whereas for semiconducting-type ones, they are attractive for small lengths of the nanotube and repulsive for large lengths.

  13. Computation of Casimir interactions between arbitrary three-dimensional objects with arbitrary material properties

    International Nuclear Information System (INIS)

    Reid, M. T. Homer; White, Jacob; Johnson, Steven G.

    2011-01-01

    We extend a recently introduced method for computing Casimir forces between arbitrarily shaped metallic objects [M. T. H. Reid et al., Phys. Rev. Lett. 103 040401 (2009)] to allow treatment of objects with arbitrary material properties, including imperfect conductors, dielectrics, and magnetic materials. Our original method considered electric currents on the surfaces of the interacting objects; the extended method considers both electric and magnetic surface current distributions, and obtains the Casimir energy of a configuration of objects in terms of the interactions of these effective surface currents. Using this new technique, we present the first predictions of Casimir interactions in several experimentally relevant geometries that would be difficult to treat with any existing method. In particular, we investigate Casimir interactions between dielectric nanodisks embedded in a dielectric fluid; we identify the threshold surface-surface separation at which finite-size effects become relevant, and we map the rotational energy landscape of bound nanoparticle diclusters.

  14. Finite difference computation of Casimir forces

    International Nuclear Information System (INIS)

    Pinto, Fabrizio

    2016-01-01

    In this Invited paper, we begin by a historical introduction to provide a motivation for the classical problems of interatomic force computation and associated challenges. This analysis will lead us from early theoretical and experimental accomplishments to the integration of these fascinating interactions into the operation of realistic, next-generation micro- and nanodevices both for the advanced metrology of fundamental physical processes and in breakthrough industrial applications. Among several powerful strategies enabling vastly enhanced performance and entirely novel technological capabilities, we shall specifically consider Casimir force time-modulation and the adoption of non-trivial geometries. As to the former, the ability to alter the magnitude and sign of the Casimir force will be recognized as a crucial principle to implement thermodynamical nano-engines. As to the latter, we shall first briefly review various reported computational approaches. We shall then discuss the game-changing discovery, in the last decade, that standard methods of numerical classical electromagnetism can be retooled to formulate the problem of Casimir force computation in arbitrary geometries. This remarkable development will be practically illustrated by showing that such an apparently elementary method as standard finite-differencing can be successfully employed to numerically recover results known from the Lifshitz theory of dispersion forces in the case of interacting parallel-plane slabs. Other geometries will be also be explored and consideration given to the potential of non-standard finite-difference methods. Finally, we shall introduce problems at the computational frontier, such as those including membranes deformed by Casimir forces and the effects of anisotropic materials. Conclusions will highlight the dramatic transition from the enduring perception of this field as an exotic application of quantum electrodynamics to the recent demonstration of a human climbing

  15. The generalized Abel-Plana formula. Applications to Bessel functions and Casimir effect

    International Nuclear Information System (INIS)

    Saharian, A.A.; Institute of Applied Problems in Physics NAS RA, Yerevan; Abdus Salam International Centre for Theoretical Physics, Trieste

    2000-02-01

    One of the most efficient methods to obtain the vacuum expectation values for the physical observables in the Casimir effect is based on using the Abel-Plana summation formula. This allows us to derive the regularized quantities in a manifestly cutoff independent way and present them in the form of strongly convergent integrals. However, the application of Abel-Plana formula, in its usual form, is restricted by simple geometries when the eigenmodes have a simple dependence on quantum numbers. The author generalized the Abel-Plana formula which essentially enlarges its application range. Based on this generalization, formulae have been obtained for various types of series over the zeros of some combinations of Bessel functions and for integrals involving these functions. It has been shown that these results generalize the special cases existing in literature. Further, the derived summation formulae have been used to summarize series arising in the mode summation approach to the Casimir effect for spherically and cylindrically symmetric boundaries. This allows us to extract the divergent parts from the vacuum expectation values for the local physical observables in a manifestly cutoff independent way. The present paper reviews these results. Some new considerations are also added. (author)

  16. Atomic physics and quantum optics using superconducting circuits: from the Dynamical Casimir effect to Majorana fermions

    Science.gov (United States)

    Nori, Franco

    2012-02-01

    This talk will present an overview of some of our recent results on atomic physics and quantum optics using superconducting circuits. Particular emphasis will be given to photons interacting with qubits, interferometry, the Dynamical Casimir effect, and also studying Majorana fermions using superconducting circuits.[4pt] References available online at our web site:[0pt] J.Q. You, Z.D. Wang, W. Zhang, F. Nori, Manipulating and probing Majorana fermions using superconducting circuits, (2011). Arxiv. J.R. Johansson, G. Johansson, C.M. Wilson, F. Nori, Dynamical Casimir effect in a superconducting coplanar waveguide, Phys. Rev. Lett. 103, 147003 (2009). [0pt] J.R. Johansson, G. Johansson, C.M. Wilson, F. Nori, Dynamical Casimir effect in superconducting microwave circuits, Phys. Rev. A 82, 052509 (2010). [0pt] C.M. Wilson, G. Johansson, A. Pourkabirian, J.R. Johansson, T. Duty, F. Nori, P. Delsing, Observation of the Dynamical Casimir Effect in a superconducting circuit. Nature, in press (Nov. 2011). P.D. Nation, J.R. Johansson, M.P. Blencowe, F. Nori, Stimulating uncertainty: Amplifying the quantum vacuum with superconducting circuits, Rev. Mod. Phys., in press (2011). [0pt] J.Q. You, F. Nori, Atomic physics and quantum optics using superconducting circuits, Nature 474, 589 (2011). [0pt] S.N. Shevchenko, S. Ashhab, F. Nori, Landau-Zener-Stuckelberg interferometry, Phys. Reports 492, 1 (2010). [0pt] I. Buluta, S. Ashhab, F. Nori. Natural and artificial atoms for quantum computation, Reports on Progress in Physics 74, 104401 (2011). [0pt] I.Buluta, F. Nori, Quantum Simulators, Science 326, 108 (2009). [0pt] L.F. Wei, K. Maruyama, X.B. Wang, J.Q. You, F. Nori, Testing quantum contextuality with macroscopic superconducting circuits, Phys. Rev. B 81, 174513 (2010). [0pt] J.Q. You, X.-F. Shi, X. Hu, F. Nori, Quantum emulation of a spin system with topologically protected ground states using superconducting quantum circuit, Phys. Rev. A 81, 063823 (2010).

  17. Thermal Casimir effect in Kerr spacetime with quintessence and massive gravitons

    Energy Technology Data Exchange (ETDEWEB)

    Bezerra, V.B. [Universidade Federal da Paraiba, Departamento de Fisica, Joao Pessoa, PB (Brazil); Christiansen, H.R. [Ciencia e Tecnologia do Ceara (IFCE), Departamento de Fisica, Instituto Federal de Educacao, Sobral, CE (Brazil); Cunha, M.S. [Universidade Estadual do Ceara, Grupo de Fisica Teorica (GFT), Fortaleza, CE (Brazil); Muniz, C.R.; Tahim, M.O. [Universidade Estadual do Ceara, Faculdade de Educacao, Ciencias e Letras do Sertao Central, Quixada, CE (Brazil)

    2017-11-15

    Starting from an analytical expression for the Helmholtz free energy we calculate the thermal corrections to the Casimir energy density and entropy within nearby ideal parallel plates in the vacuum of a massless scalar field. Our framework is the Kerr spacetime in the presence of quintessence and massive gravitons. The high and low temperature regimes are especially analyzed in order to distinguish the main contributions. For instance, in the high temperature regime, we show that the force between the plates is repulsive and grows with both the quintessence and the massive gravitons. Regarding the Casimir entropy, our results are in agreement with the Nernst heat theorem and therefore confirm the third law of thermodynamics in the present scenario. (orig.)

  18. Measurements of the Casimir-Lifshitz force in fluids: The effect of electrostatic forces and Debye screening

    Science.gov (United States)

    Munday, J. N.; Capasso, Federico; Parsegian, V. Adrian; Bezrukov, Sergey M.

    2008-09-01

    We present detailed measurements of the Casimir-Lifshitz force between two gold surfaces (a sphere and a plate) immersed in ethanol and study the effect of residual electrostatic forces, which are dominated by static fields within the apparatus and can be reduced with proper shielding. Electrostatic forces are further reduced by Debye screening through the addition of salt ions to the liquid. Additionally, the salt leads to a reduction of the Casimir-Lifshitz force by screening the zero-frequency contribution to the force; however, the effect is small between gold surfaces at the measured separations and within experimental error. An improved calibration procedure is described and compared with previous methods. Finally, the experimental results are compared with Lifshitz’s theory and found to be consistent for the materials used in the experiment.

  19. Casimir interactions between graphene sheets and metamaterials

    International Nuclear Information System (INIS)

    Drosdoff, D.; Woods, Lilia M.

    2011-01-01

    The Casimir force between graphene sheets and metamaterials is studied. Theoretical results based on the Lifshitz theory for layered, planar, two-dimensional systems in media are presented. We consider graphene-graphene, graphene-metamaterial, and metal-graphene-metamaterial configurations. We find that quantum effects of the temperature-dependent force are not apparent until the submicron range. In contrast to results with bulk dielectric and bulk metallic materials, no Casimir repulsion is found when graphene is placed on top of a magnetically active metamaterial substrate, regardless of the strength of the low-frequency magnetic response. In the case of the metal-graphene-metamaterial setting, repulsion between the metamaterial and the metal-graphene system is possible only when the dielectric response from the metal contributes significantly.

  20. A Generalization of Electromagnetic Fluctuation-Induced Casimir Energy

    Directory of Open Access Journals (Sweden)

    Yi Zheng

    2015-01-01

    Full Text Available Intermolecular forces responsible for adhesion and cohesion can be classified according to their origins; interactions between charges, ions, random dipole—random dipole (Keesom, random dipole—induced dipole (Debye are due to electrostatic effects; covalent bonding, London dispersion forces between fluctuating dipoles, and Lewis acid-base interactions are due to quantum mechanical effects; pressure and osmotic forces are of entropic origin. Of all these interactions, the London dispersion interaction is universal and exists between all types of atoms as well as macroscopic objects. The dispersion force between macroscopic objects is called Casimir/van der Waals force. It results from alteration of the quantum and thermal fluctuations of the electrodynamic field due to the presence of interfaces and plays a significant role in the interaction between macroscopic objects at micrometer and nanometer length scales. This paper discusses how fluctuational electrodynamics can be used to determine the Casimir energy/pressure between planar multilayer objects. Though it is confirmation of the famous work of Dzyaloshinskii, Lifshitz, and Pitaevskii (DLP, we have solved the problem without having to use methods from quantum field theory that DLP resorted to. Because of this new approach, we have been able to clarify the contributions of propagating and evanescent waves to Casimir energy/pressure in dissipative media.

  1. Modeling the influence of the Casimir force on the pull-in instability of nanowire-fabricated nanotweezers

    Science.gov (United States)

    Farrokhabadi, Amin; Mokhtari, Javad; Rach, Randolph; Abadyan, Mohamadreza

    2015-09-01

    The Casimir force can strongly interfere with the pull-in performance of ultra-small structures. The strength of the Casimir force is significantly affected by the geometries of interacting bodies. Previous investigators have exclusively studied the effect of the Casimir force on the electromechanical instability of nanostructures with planar geometries. However no work has yet considered this effect on the pull-in instability of systems with cylindrical geometries such as nanotweezers fabricated from nanotube/nanowires. In our present work, the influence of the Casimir attraction on the electrostatic response and pull-in instability of nanotweezers fabricated from cylindrical conductive nanowires/nanotubes is theoretically investigated. An asymptotic solution, based on scattering theory, is applied to consider the effect of vacuum fluctuations in the theoretical model. The Euler-Bernoulli beam model is employed, in conjunction with the size-dependent modified couple stress continuum theory, to derive the governing equation of the nanotweezers. The governing nonlinear equations are solved by two different approaches, i.e., the modified Adomian-Padé method (MAD-Padé) and a numerical solution. Various aspects of the problem, i.e., the variation of pull-in parameters, effect of geometry, coupling between the Casimir force and size dependency effects and comparison with the van der Waals force regime are discussed.

  2. The supersymmetric Casimir effect and quantum creation of the universe with nontrivial topology

    International Nuclear Information System (INIS)

    Goncharov, Yu.P.; Bytsenko, A.A.

    1985-01-01

    We estimate the probability of quantum creation of the universe, having the spatial topology (S 1 ) 3 , and filled with the fields of minimal N=1 supergravity, in the semiclassical approximation. After creation, inflation of the universe occurs due to the topological Casimir effect. Creation of the universe with an isotropic topology is found to be the most preferable. (orig.)

  3. Investigating the Role of Ferromagnetic Materials on the Casimir Force & Investigation of the Van Der Waals/Casimir Force with Graphene

    Energy Technology Data Exchange (ETDEWEB)

    Mohideen, Umar [Univ. of California, Riverside, CA (United States)

    2015-04-14

    Duration of award was from 4/15/10-4/14/15. In this grant period our contributions to the field of VdW/Casimir forces are 24 refereed publications in journals such as Physical Review Letters (4) [1-4], Physical Review B (10) [5-14], Physical Review D (2) [15,16], Applied Physics Letters (1) [17], Review of Scientific Instruments (1) [18] and the International Journal of Modern Physics A (5) [19-23] and B(1) (invited review article [24]). We presented 2 plenary conference talks, 3 lectures at the Pan American School on Frontiers in Casimir Physics, 2 conferences, 1 colloquium and 11 APS talks. If publications are restricted to only those with direct connection to the aims proposed in the prior grant period, then it will be a total of 12: Physical Review Letters (3) [2-4], Physical Review B (6) [6-8,12,13,25], Review of Scientific Instruments (1) [18], International Journal of Modern Physics A (1) [19] and B(1) [169]. A brief aggregated description of the directly connected accomplishments is below. The following topics are detailed: dispersion force measurements with graphene, dispersion force from ferromagnetic metals, conclusion on role of electrostatic patches, UV radiation induced modification of the Casimir force, low temperature measurement of the Casimir force, and Casimir force from thin fluctuating membranes.

  4. Repulsive Casimir-Polder forces from cosmic strings

    International Nuclear Information System (INIS)

    Saharian, A.A.; Kotanjyan, A.S.

    2011-01-01

    We investigate the Casimir-Polder force acting on a polarizable microparticle in the geometry of a straight cosmic string. In order to develop this analysis we evaluate the electromagnetic field Green tensor on the imaginary frequency axis. The expression for the Casimir-Polder force is derived in the general case of anisotropic polarizability. In dependence on the eigenvalues for the polarizability tensor and of the orientation of its principal axes, the Casimir-Polder force can be either repulsive or attractive. Moreover, there are situations where the force changes the sign with separation. We show that for an isotropic polarizability tensor the force is always repulsive. At large separations between the microparticle and the string, the force varies inversely with the fifth power of the distance. In the non-retarded regime, corresponding to separations smaller than the relevant transition wavelengths, the force decays with the inverse fourth power of the distance. In the case of anisotropic polarizability, the dependence of the Casimir-Polder potential on the orientation of the polarizability tensor principal axes also leads to a moment of force acting on the particle. (orig.)

  5. Casimir Effect and Black Hole Radiation

    Science.gov (United States)

    Rahbardehghan, S.

    2018-03-01

    The gravitational field of a black hole intrinsically creates a potential barrier consisted of two reflecting boundaries; the first one far from the hole and the second one in the vicinity of its horizon. With respect to this fact and assuming the boundaries as good conductors (in view of an observer near the horizon just outside the second boundary), in a series of papers, R.M. Nugayev by considering a conformally coupled massless scalar field and based on the calculations of Candelas and Deutsch (the accelerated-mirror results) has claimed that " ...the existence of the potential barrier is as crucial for Hawking evaporation as the existence of the horizon". In this paper, by taking the same assumptions, through straightforward reasonings, we explicitly show that contrary to this claim, the effects of the first boundary on the black hole radiation are quite negligible. Moreover, the inclusion of the second boundary makes the situation more complicated, because the induced Casimir energy-momentum tensor by this boundary in its vicinity is divergent of order δ ^{-4} ( δ is the distance to the boundary).

  6. Number of particle creation and decoherence in the nonideal dynamical Casimir effect at finite temperature

    International Nuclear Information System (INIS)

    Celeri, L.C.; Pascoal, F.; Ponte, M.A. de; Moussa, M.H.Y.

    2009-01-01

    In this work we investigate the dynamical Casimir effect in a nonideal cavity by deriving an effective Hamiltonian. We first compute a general expression for the average number of particle creation, applicable for any law of motion of the cavity boundary, under the only restriction of small velocities. We also compute a general expression for the linear entropy of an arbitrary state prepared in a selected mode, also applicable for any law of motion of a slow moving boundary. As an application of our results we have analyzed both the average number of particle creation and linear entropy within a particular oscillatory motion of the cavity boundary. On the basis of these expressions we develop a comprehensive analysis of the resonances in the number of particle creation in the nonideal dynamical Casimir effect. We also demonstrate the occurrence of resonances in the loss of purity of the initial state and estimate the decoherence times associated with these resonances. Since our results were obtained in the framework of the perturbation theory, they are restricted, under resonant conditions, to a short-time approximation.

  7. Casimir energy for twisted piecewise uniform bosonic strings

    International Nuclear Information System (INIS)

    Lu, J.; Huang, B.; Shanghai, Teachers Univ.

    1998-01-01

    The Casimir energy for the transverse oscillations of piecewise uniform bosonic strings with either untwisted or twisted continuous conditions is discussed. After calculating the analytic values of zeros of the dispersion function under certain conditions, is obtained the Casimir energy for both open and closed bosonic strings composed of two or three segments

  8. Casimir elements of epsilon Lie algebras

    International Nuclear Information System (INIS)

    Scheunert, M.

    1982-10-01

    The classical framework for investigating the Casimir elements of a Lie algebra is generalized to the case of an epsilon Lie algebra L. We construct the standard L-module isomorphism of the epsilon-symmetric algebra of L onto its enveloping algebra and we introduce the Harish-Chandra homomorphism. In case the generators of L can be written in a canonical two-index form, we construct the associated standard sequence of Casimir elements and derive a formula for their eigenvalues in an arbitrary highest weight module. (orig.)

  9. Casimir effect in spherical shells

    International Nuclear Information System (INIS)

    Ruggiero, J.R.

    1985-01-01

    The analytic regularization method is applied to study the Casimir effect for spherical cavities. Although many works have been presented in the past few years, problems related to the elimination of the regulator parameter still remain. A way to calculate the zero point energy of a perfectly conducting spherical shell which is a miscellaneous of those presented early is here proposed, How a cancelation of divergent terms occurs and how a finite parte is obtained after the elimination of the regulator parameter is shown. As a by-product the zero point energy of the interior vibration modes is obtained and this has some relevance to the quarks bag model. This relev ance is also discussed. The calculation of the energy fom the density view is also discussed. Some works in this field are criticized. The logarithmic divergent terms in the zero point energy are studied when the interior and exterior of the sphere are considered as a medium not dispersive and characterized by a dielectric constants ε 1 and ε 2 and peermeability constants μ 1 and μ 2 respectivelly. The logarithmic divergent terms are not present in the case of ε i μ i =K, with K some constant and i=1,2. (author) [pt

  10. On the static Casimir effect with parity-breaking mirrors

    Energy Technology Data Exchange (ETDEWEB)

    Fosco, C.D. [Comision Nacional de Energia Atomica, Centro Atomico Bariloche and Instituto Balseiro, Bariloche (Argentina); Remaggi, M.L. [Universidad Nacional de Cuyo, Facultad de Ciencias Exactas y Naturales, Mendoza (Argentina)

    2017-03-15

    We study the Casimir interaction energy due to the vacuum fluctuations of the electromagnetic (EM) field in the presence of two mirrors, described by 2+1-dimensional, generally nonlocal actions, which may contain both parity-conserving and parity-breaking terms. We compare the results with the ones corresponding to Chern-Simons boundary conditions and evaluate the interaction energy for several particular situations. (orig.)

  11. Singular perturbations with boundary conditions and the Casimir effect in the half space

    Science.gov (United States)

    Albeverio, S.; Cognola, G.; Spreafico, M.; Zerbini, S.

    2010-06-01

    We study the self-adjoint extensions of a class of nonmaximal multiplication operators with boundary conditions. We show that these extensions correspond to singular rank 1 perturbations (in the sense of Albeverio and Kurasov [Singular Perturbations of Differential Operaters (Cambridge University Press, Cambridge, 2000)]) of the Laplace operator, namely, the formal Laplacian with a singular delta potential, on the half space. This construction is the appropriate setting to describe the Casimir effect related to a massless scalar field in the flat space-time with an infinite conducting plate and in the presence of a pointlike "impurity." We use the relative zeta determinant (as defined in the works of Müller ["Relative zeta functions, relative determinants and scattering theory," Commun. Math. Phys. 192, 309 (1998)] and Spreafico and Zerbini ["Finite temperature quantum field theory on noncompact domains and application to delta interactions," Rep. Math. Phys. 63, 163 (2009)]) in order to regularize the partition function of this model. We study the analytic extension of the associated relative zeta function, and we present explicit results for the partition function and for the Casimir force.

  12. The field theory of symmetrical layered electrolytic systems and the thermal Casimir effect

    International Nuclear Information System (INIS)

    Dean, D S; Horgan, R R

    2005-01-01

    We present a general extension of a field-theoretic approach developed in earlier papers to the calculation of the free energy of symmetrically layered electrolytic systems which is based on the sine-Gordon field theory for the Coulomb gas. The method is to construct the partition function in terms of the Feynman evolution kernel in the Euclidean time variable associated with the coordinate normal to the surfaces defining the layered structure. The theory is applicable to cylindrical systems and its development is motivated by the possibility that a static van der Waals or thermal Casimir force could provide an attractive force stabilizing a dielectric tube formed from a lipid bilayer, an example of which is provided by the t-tubules occurring in certain muscle cells. In this context, we apply the theory to the calculation of the thermal Casimir effect for a dielectric tube of radius R and thickness δ formed from such a membrane in water. In a grand canonical approach we find that the leading contribution to the Casimir energy behaves like -k B TLκ C /R which gives rise to an attractive force which tends to contract the tube radius. We find that κ C ∼0.3 for the case of typical lipid membrane t-tubules. We conclude that except in the case of a very soft membrane this force is insufficient to stabilize such tubes against the bending stress which tends to increase the radius. We briefly discuss the role of the lipid membrane reservoir implicit in the approach and whether its nature in biological systems may possibly lead to a stabilizing mechanism for such lipid tubes

  13. Particle creation by a black hole as a consequence of the Casimir effect

    International Nuclear Information System (INIS)

    Nugayev, R.M.

    1987-01-01

    Particle creation by a blackhole is investigated in terms of temperature corrections to the Casimir effect. The reduction of the Hawking effect to more familiar effects observed in the laboratory enables us to reveal the mechanism of particle creation. The blackbody nature of the Hawking radiation is due to the interaction of virtual particles with the surface of a ''cavity'' formed by the Schwarzschild gravitational field potential barrier. These particles are ''squeezed out'' by the contraction of the potential barrier and appear to an observer at J + as the real blackbody ones. (orig.)

  14. Laser Cooling and Trapping of Neutral Strontium for Spectroscopic Measurements of Casimir-Polder Potentials

    Science.gov (United States)

    Cook, Eryn C.

    Casimir and Casimir-Polder effects are forces between electrically neutral bodies and particles in vacuum, arising entirely from quantum fluctuations. The modification to the vacuum electromagnetic-field modes imposed by the presence of any particle or surface can result in these mechanical forces, which are often the dominant interaction at small separations. These effects play an increasingly critical role in the operation of micro- and nano-mechanical systems as well as miniaturized atomic traps for precision sensors and quantum-information devices. Despite their fundamental importance, calculations present theoretical and numeric challenges, and precise atom-surface potential measurements are lacking in many geometric and distance regimes. The spectroscopic measurement of Casimir-Polder-induced energy level shifts in optical-lattice trapped atoms offers a new experimental method to probe atom-surface interactions. Strontium, the current front-runner among optical frequency metrology systems, has demonstrated characteristics ideal for such precision measurements. An alkaline earth atom possessing ultra-narrow intercombination transitions, strontium can be loaded into an optical lattice at the "magic" wavelength where the probe transition is unperturbed by the trap light. Translation of the lattice will permit controlled transport of tightly-confined atomic samples to well-calibrated atom-surface separations, while optical transition shifts serve as a direct probe of the Casimir-Polder potential. We have constructed a strontium magneto-optical trap (MOT) for future Casimir-Polder experiments. This thesis will describe the strontium apparatus, initial trap performance, and some details of the proposed measurement procedure.

  15. Casimir forces in multilayer magnetodielectrics with both gain and loss

    DEFF Research Database (Denmark)

    Amooghorban, Ehsan; Wubs, Martijn; Mortensen, N. Asger

    2011-01-01

    of the amplifying medium, with negative imaginary parts in finite frequency intervals, are identified and their relationships to microscopic coupling functions are determined. By carefully relating the two-point functions of the field theory to the optical Green functions, we calculate the Casimir energy...... and Casimir forces for a multilayer magnetodielectric medium with both gain and loss. We point out the essential differences with a purely passive layered medium. For a single layer, we find different bounds on the Casimir force for fully amplifying and for lossy media. The force is attractive in both cases...

  16. Casimir free energy of dielectric films: classical limit, low-temperature behavior and control.

    Science.gov (United States)

    Klimchitskaya, G L; Mostepanenko, V M

    2017-07-12

    The Casimir free energy of dielectric films, both free-standing in vacuum and deposited on metallic or dielectric plates, is investigated. It is shown that the values of the free energy depend considerably on whether the calculation approach used neglects or takes into account the dc conductivity of film material. We demonstrate that there are material-dependent and universal classical limits in the former and latter cases, respectively. The analytic behavior of the Casimir free energy and entropy for a free-standing dielectric film at low temperature is found. According to our results, the Casimir entropy goes to zero when the temperature vanishes if the calculation approach with neglected dc conductivity of a film is employed. If the dc conductivity is taken into account, the Casimir entropy takes the positive value at zero temperature, depending on the parameters of a film, i.e. the Nernst heat theorem is violated. By considering the Casimir free energy of SiO 2 and Al 2 O 3 films deposited on a Au plate in the framework of two calculation approaches, we argue that physically correct values are obtained by disregarding the role of dc conductivity. A comparison with the well known results for the configuration of two parallel plates is made. Finally, we compute the Casimir free energy of SiO 2 , Al 2 O 3 and Ge films deposited on high-resistivity Si plates of different thicknesses and demonstrate that it can be positive, negative and equal to zero. The effect of illumination of a Si plate with laser light is considered. Possible applications of the obtained results to thin films used in microelectronics are discussed.

  17. Casimir free energy of dielectric films: classical limit, low-temperature behavior and control

    Science.gov (United States)

    Klimchitskaya, G. L.; Mostepanenko, V. M.

    2017-07-01

    The Casimir free energy of dielectric films, both free-standing in vacuum and deposited on metallic or dielectric plates, is investigated. It is shown that the values of the free energy depend considerably on whether the calculation approach used neglects or takes into account the dc conductivity of film material. We demonstrate that there are material-dependent and universal classical limits in the former and latter cases, respectively. The analytic behavior of the Casimir free energy and entropy for a free-standing dielectric film at low temperature is found. According to our results, the Casimir entropy goes to zero when the temperature vanishes if the calculation approach with neglected dc conductivity of a film is employed. If the dc conductivity is taken into account, the Casimir entropy takes the positive value at zero temperature, depending on the parameters of a film, i.e. the Nernst heat theorem is violated. By considering the Casimir free energy of SiO2 and Al2O3 films deposited on a Au plate in the framework of two calculation approaches, we argue that physically correct values are obtained by disregarding the role of dc conductivity. A comparison with the well known results for the configuration of two parallel plates is made. Finally, we compute the Casimir free energy of SiO2, Al2O3 and Ge films deposited on high-resistivity Si plates of different thicknesses and demonstrate that it can be positive, negative and equal to zero. The effect of illumination of a Si plate with laser light is considered. Possible applications of the obtained results to thin films used in microelectronics are discussed.

  18. Measured long-range repulsive Casimir-Lifshitz forces.

    Science.gov (United States)

    Munday, J N; Capasso, Federico; Parsegian, V Adrian

    2009-01-08

    Quantum fluctuations create intermolecular forces that pervade macroscopic bodies. At molecular separations of a few nanometres or less, these interactions are the familiar van der Waals forces. However, as recognized in the theories of Casimir, Polder and Lifshitz, at larger distances and between macroscopic condensed media they reveal retardation effects associated with the finite speed of light. Although these long-range forces exist within all matter, only attractive interactions have so far been measured between material bodies. Here we show experimentally that, in accord with theoretical prediction, the sign of the force can be changed from attractive to repulsive by suitable choice of interacting materials immersed in a fluid. The measured repulsive interaction is found to be weaker than the attractive. However, in both cases the magnitude of the force increases with decreasing surface separation. Repulsive Casimir-Lifshitz forces could allow quantum levitation of objects in a fluid and lead to a new class of switchable nanoscale devices with ultra-low static friction.

  19. Bogoliubov transformation for quantum fields in (S1)d x RD-d topology and applications to the Casimir effect

    International Nuclear Information System (INIS)

    Khanna, F C; Malbouisson, J M C; Santana, A E

    2009-01-01

    A Bogoliubov transformation accounting simultaneously for spatial compactifica-tion and thermal effects is introduced. The fields are described in a Γ D d = S 1 1 x ... x S 1 d x R D-d topology, and the Bogoliubov transformation is derived by a generalization of the thermofield dynamics formalism, a real-time finite-temperature quantum field theory. We consider the Casimir effect for Maxwell and Dirac fields and for a non-interacting massless QCD at finite temperature. For the fermion sector in a cubic box, we analyze the temperature at which the Casimir pressure changes its sign from attractive to repulsive. This critical temperature is approximately 200 MeV when the edge of the cube is of the order of the confining lengths (∼ 1 : fm) for quarks in baryons.

  20. Intensifying the Casimir force between two silicon substrates within three different layers of materials

    International Nuclear Information System (INIS)

    Seyedzahedi, A.; Moradian, A.; Setare, M.R.

    2016-01-01

    We investigate the Casimir force for a system composed of two thick slabs as substrates within three different homogeneous layers. We use the scattering approach along with the Matsubara formalism in order to calculate the Casimir force at finite temperature. First, we focus on constructing the reflection matrices and then we calculate the Casimir force for a water–lipid system. According to the conventional use of silicon as a substrate, we apply the formalism to calculate the Casimir force for layers of Au, VO 2 , mica, KCl and foam rubber on the thick slabs of silicon. Afterwards, introducing an increasing factor, we compare our results with Lifshitz force in the vacuum between two semispaces of silicon in order to illustrate the influence of the layers on intensifying the Casimir force. We also calculate the Casimir force between two slabs of the forementioned materials with finite thicknesses to indicate the substrate's role in increasing the obtained Casimir force. Our simple calculation is interesting since one can extend it along with the Rigorous Coupled Wave Analysis to systems containing inhomogeneous layers as good candidates for designing nanomechanical devices.

  1. Intensifying the Casimir force between two silicon substrates within three different layers of materials

    Energy Technology Data Exchange (ETDEWEB)

    Seyedzahedi, A. [Department of Science, University of Kurdistan, Sanandaj (Iran, Islamic Republic of); Moradian, A., E-mail: a.moradian@uok.ac.ir [Department of Science, Campus of Bijar, University of Kurdistan, Bijar (Iran, Islamic Republic of); Setare, M.R., E-mail: rezakord@ipm.ir [Department of Science, University of Kurdistan, Sanandaj (Iran, Islamic Republic of)

    2016-04-01

    We investigate the Casimir force for a system composed of two thick slabs as substrates within three different homogeneous layers. We use the scattering approach along with the Matsubara formalism in order to calculate the Casimir force at finite temperature. First, we focus on constructing the reflection matrices and then we calculate the Casimir force for a water–lipid system. According to the conventional use of silicon as a substrate, we apply the formalism to calculate the Casimir force for layers of Au, VO{sub 2}, mica, KCl and foam rubber on the thick slabs of silicon. Afterwards, introducing an increasing factor, we compare our results with Lifshitz force in the vacuum between two semispaces of silicon in order to illustrate the influence of the layers on intensifying the Casimir force. We also calculate the Casimir force between two slabs of the forementioned materials with finite thicknesses to indicate the substrate's role in increasing the obtained Casimir force. Our simple calculation is interesting since one can extend it along with the Rigorous Coupled Wave Analysis to systems containing inhomogeneous layers as good candidates for designing nanomechanical devices.

  2. Casimir potential of a compact object enclosed by a spherical cavity

    International Nuclear Information System (INIS)

    Zaheer, Saad; Rahi, Sahand Jamal; Emig, Thorsten; Jaffe, Robert L.

    2010-01-01

    We study the electromagnetic Casimir interaction of a compact object contained inside a closed cavity of another compact object. We express the interaction energy in terms of the objects' scattering matrices and translation matrices that relate the coordinate systems appropriate to each object. When the enclosing object is an otherwise empty metallic spherical shell, much larger than the internal object, and the two are sufficiently separated, the Casimir force can be expressed in terms of the static electric and magnetic multipole polarizabilities of the internal object, which is analogous to the Casimir-Polder result. Although it is not a simple power law, the dependence of the force on the separation of the object from the containing sphere is a universal function of its displacement from the center of the sphere, independent of other details of the object's electromagnetic response. Furthermore, we compute the exact Casimir force between two metallic spheres contained one inside the other at arbitrary separations. Finally, we combine our results with earlier work on the Casimir force between two spheres to obtain data on the leading-order correction to the proximity force approximation for two metallic spheres both outside and within one another.

  3. Casimir force between two Aharonov-Bohm selenoids

    International Nuclear Information System (INIS)

    Duru, I.H.

    1989-06-01

    We show that a force of Casimir type case be associated with the Aharonov-Bohm effect. We consider two parallel, infinitely long and thin selenoids confining the quantized fluxes n 1 and n 2 within them. Using the Green function method, the vacuum expectation value of the system's energy which includes ''self interaction'' terms and a finite ''mutual interaction'' term is calculated. 8 refs

  4. Casimir forces in the time domain: Theory

    International Nuclear Information System (INIS)

    Rodriguez, Alejandro W.; McCauley, Alexander P.; Joannopoulos, John D.; Johnson, Steven G.

    2009-01-01

    We present a method to compute Casimir forces in arbitrary geometries and for arbitrary materials based on the finite-difference time-domain (FDTD) scheme. The method involves the time evolution of electric and magnetic fields in response to a set of current sources, in a modified medium with frequency-independent conductivity. The advantage of this approach is that it allows one to exploit existing FDTD software, without modification, to compute Casimir forces. In this paper, we focus on the derivation, implementation choices, and essential properties of the time-domain algorithm, both considered analytically and illustrated in the simplest parallel-plate geometry.

  5. Zeta Function Regularization in Casimir Effect Calculations and J. S. Dowker's Contribution

    Science.gov (United States)

    Elizalde, Emilio

    2012-07-01

    A summary of relevant contributions, ordered in time, to the subject of operator zeta functions and their application to physical issues is provided. The description ends with the seminal contributions of Stephen Hawking and Stuart Dowker and collaborators, considered by many authors as the actual starting point of the introduction of zeta function regularization methods in theoretical physics, in particular, for quantum vacuum fluctuation and Casimir effect calculations. After recalling a number of the strengths of this powerful and elegant method, some of its limitations are discussed. Finally, recent results of the so called operator regularization procedure are presented.

  6. Casimir pistons with general boundary conditions

    Directory of Open Access Journals (Sweden)

    Guglielmo Fucci

    2015-02-01

    Full Text Available In this work we analyze the Casimir energy and force for a scalar field endowed with general self-adjoint boundary conditions propagating in a higher dimensional piston configuration. The piston is constructed as a direct product I×N, with I=[0,L]⊂R and N a smooth, compact Riemannian manifold with or without boundary. The study of the Casimir energy and force for this configuration is performed by employing the spectral zeta function regularization technique. The obtained analytic results depend explicitly on the spectral zeta function associated with the manifold N and the parameters describing the general boundary conditions imposed. These results are then specialized to the case in which the manifold N is a d-dimensional sphere.

  7. Surface contact potential patches and Casimir force measurements

    International Nuclear Information System (INIS)

    Kim, W. J.; Sushkov, A. O.; Lamoreaux, S. K.; Dalvit, D. A. R.

    2010-01-01

    We present calculations of contact potential surface patch effects that simplify previous treatments. It is shown that, because of the linearity of Laplace's equation, the presence of patch potentials does not affect an electrostatic calibration of a two-plate Casimir measurement apparatus. Using models that include long-range variations in the contact potential across the plate surfaces, a number of experimental observations can be reproduced and explained. For these models, numerical calculations show that if a voltage is applied between the plates which minimizes the force, a residual electrostatic force persists, and that the minimizing potential varies with distance. The residual force can be described by a fit to a simple two-parameter function involving the minimizing potential and its variation with distance. We show the origin of this residual force by use of a simple parallel capacitor model. Finally, the implications of a residual force that varies in a manner different from 1/d on the accuracy of previous Casimir measurements is discussed.

  8. Casimir effect in rugby-ball type flux compactifications

    International Nuclear Information System (INIS)

    Elizalde, Emilio; Minamitsuji, Masato; Naylor, Wade

    2007-01-01

    As a continuation of the work by Minamitsuji, Naylor, and Sasaki [J. High Energy Phys. 12 (2006) 079], we discuss the Casimir effect for a massless bulk scalar field in a 4D toy model of a 6D warped flux compactification model, to stabilize the volume modulus. The one-loop effective potential for the volume modulus has a form similar to the Coleman-Weinberg potential. The stability of the volume modulus against quantum corrections is related to an appropriate heat kernel coefficient. However, to make any physical predictions after volume stabilization, knowledge of the derivative of the zeta function, ζ ' (0) (in a conformally related spacetime) is also required. By adding up the exact mass spectrum using zeta-function regularization, we present a revised analysis of the effective potential. Finally, we discuss some physical implications, especially concerning the degree of the hierarchy between the fundamental energy scales on the branes. For a larger degree of warping our new results are very similar to the ones given by Minamitsuji, Naylor, and Sasaki [J. High Energy Phys. 12 (2006) 079] and imply a larger hierarchy. In the nonwarped (rugby ball) limit the ratio tends to converge to the same value, independently of the bulk dilaton coupling

  9. Efficient Computation of Casimir Interactions between Arbitrary 3D Objects

    International Nuclear Information System (INIS)

    Reid, M. T. Homer; Rodriguez, Alejandro W.; White, Jacob; Johnson, Steven G.

    2009-01-01

    We introduce an efficient technique for computing Casimir energies and forces between objects of arbitrarily complex 3D geometries. In contrast to other recently developed methods, our technique easily handles nonspheroidal, nonaxisymmetric objects, and objects with sharp corners. Using our new technique, we obtain the first predictions of Casimir interactions in a number of experimentally relevant geometries, including crossed cylinders and tetrahedral nanoparticles.

  10. Characterization of FGM micro-switches under electrostatic and Casimir forces

    International Nuclear Information System (INIS)

    Jia, X L; Kitipornchai, S; Yang, J

    2010-01-01

    This paper aims to investigate the nonlinear pull-in characteristics of the micro-switches made of either homogeneous material or non-homogeneous functionally graded material (FGM) with two material phases under the combined electrostatic and intermolecular Casimir force. Principle of virtual work is used to derive the governing differential equation which is then solved using differential quadrature method (DQM). Pull-in voltage and pull-in deflection are obtained for micro-switches with three different boundary conditions (i.e. fixed-fixed, simple-fixed, and simply supported). The present solutions are validated through direct comparisons with experimental and other existing results reported in previous studies. A parametric study is conducted to show the significant effects of material composition, gap ratio, slenderness ratio, Casimir force, axial residual stress on the pull-in instability.

  11. Repulsive Casimir-Polder potential by a negative reflecting surface

    Science.gov (United States)

    Yuan, Qi-Zhang

    2015-07-01

    We present a scheme to generate an all-range long repulsive Casimir-Polder potential between a perfect negative reflecting surface and a ground-state atom. The repulsive potential is stable and does not decay with time. The Casimir-Polder potential is proportional to z-2 at short atom-surface distances and to z-4 at long atom-surface distances. Because of these advantages, this potential can help in building quantum reflectors, quantum levitating devices, and waveguides for matter waves.

  12. Present status of controversies regarding the thermal Casimir force

    International Nuclear Information System (INIS)

    Mostepanenko, V M; Bezerra, V B; Decca, R S; Geyer, B; Fischbach, E; Klimchitskaya, G L; Krause, D E; Lopez, D; Romero, C

    2006-01-01

    It is well known that, beginning in 2000, the behaviour of the thermal correction to the Casimir force between real metals has been hotly debated. As was shown by several research groups, the Lifshitz theory, which provides the theoretical foundation for the calculation of both the van der Waals and Casimir forces, leads to different results depending on the model of metal conductivity used. To resolve these controversies, theoretical considerations based on the principles of thermodynamics and new experimental tests were invoked. We analyse the present status of the problem (in particular, the advantages and disadvantages of the approaches based on the surface impedance and on the Drude model dielectric function) using rigorous analytical calculations of the entropy of a fluctuating field. We also discuss the results of a new precise experiment on the determination of the Casimir pressure between two parallel plates by means of a micromechanical torsional oscillator

  13. Numerical calculation of the Casimir forces between a gold sphere and a nanocomposite sheet

    International Nuclear Information System (INIS)

    Inui, Norio; Miura, Kouji; Akamatsu, Kensuke; Ishikawa, Makoto

    2010-01-01

    The repulsive Casimir force is expected as a force which enables to levitate small objects such as machine parts used in Micro Electro Mechanical Systems (MEMS), and superlubricity in MEMS may be realized by this levitation. We study the Casimir force between a gold sphere and a nanocomposite sheet containing many nickel nanoparticles. In particular, we focus on the dependence of the Casimir force on the separation between the gold sphere and the surface of the nanocomposite sheet. The Casimir force changes from the attractive force to the repulsive force as the separation increases. The strength of the repulsive force is, however, too small to levitate MEMS parts.

  14. Numerical calculation of the Casimir forces between a gold sphere and a nanocomposite sheet

    Energy Technology Data Exchange (ETDEWEB)

    Inui, Norio; Miura, Kouji; Akamatsu, Kensuke; Ishikawa, Makoto, E-mail: inui@eng.u-hyogo.ac.j, E-mail: kmiura@auecc.aichi-edu.ac.j, E-mail: akamatsu@center.konan-u.ac.j, E-mail: makoishi@auecc.aichi-edu.ac.j

    2010-11-01

    The repulsive Casimir force is expected as a force which enables to levitate small objects such as machine parts used in Micro Electro Mechanical Systems (MEMS), and superlubricity in MEMS may be realized by this levitation. We study the Casimir force between a gold sphere and a nanocomposite sheet containing many nickel nanoparticles. In particular, we focus on the dependence of the Casimir force on the separation between the gold sphere and the surface of the nanocomposite sheet. The Casimir force changes from the attractive force to the repulsive force as the separation increases. The strength of the repulsive force is, however, too small to levitate MEMS parts.

  15. Johnson-Nyquist noise and the Casimir force between real metals at nonzero temperature

    International Nuclear Information System (INIS)

    Bimonte, Giuseppe

    2008-01-01

    It has been well known for a long time that all lossy conductors at finite temperature display an electronic noise, the Johnson-Nyquist noise, arising from the thermal agitation of electric charges inside the conductor. The existence of this noise implies that two nearby discharged conductors at finite temperature should repel each other, as a result of the electrodynamic interaction between the Johnson-Nyquist currents in either conductor and the eddy currents they induce in the other. It is suggested that this force is at the origin of the recently discovered large repulsive correction to the thermal Casimir force between two lossy metallic plates. Further support for this physical picture is obtained by studying a simple system of two linear noisy antennas. Using elementary concepts from circuit theory, we show that the repulsive force engendered by the Johnson-Nyquist noise results in the same kind of thermodynamic inconsistencies found in the Casimir problem. We show that all inconsistencies are however resolved if account is taken of capacitive effects associated with the end points of the antennas. Our findings therefore suggest that capacitive effects resulting from the finite size of the plates may be essential for a resolution of the analogous problems met in the thermal Casimir effect

  16. Materials perspective on Casimir and van der Waals interactions

    Science.gov (United States)

    Woods, L. M.; Dalvit, D. A. R.; Tkatchenko, A.; Rodriguez-Lopez, P.; Rodriguez, A. W.; Podgornik, R.

    2016-10-01

    Interactions induced by electromagnetic fluctuations, such as van der Waals and Casimir forces, are of universal nature present at any length scale between any types of systems. Such interactions are important not only for the fundamental science of materials behavior, but also for the design and improvement of micro- and nanostructured devices. In the past decade, many new materials have become available, which has stimulated the need for understanding their dispersive interactions. The field of van der Waals and Casimir forces has experienced an impetus in terms of developing novel theoretical and computational methods to provide new insights into related phenomena. The understanding of such forces has far reaching consequences as it bridges concepts in materials, atomic and molecular physics, condensed-matter physics, high-energy physics, chemistry, and biology. This review summarizes major breakthroughs and emphasizes the common origin of van der Waals and Casimir interactions. Progress related to novel ab initio modeling approaches and their application in various systems, interactions in materials with Dirac-like spectra, force manipulations through nontrivial boundary conditions, and applications of van der Waals forces in organic and biological matter are examined. The outlook of the review is to give the scientific community a materials perspective of van der Waals and Casimir phenomena and stimulate the development of experimental techniques and applications.

  17. Higher-order conductivity corrections to the Casimir force

    International Nuclear Information System (INIS)

    Bezerra, Valdir Barbosa; Klimchitskaya, Galina; Mostepanenko, Vladimir

    2000-01-01

    Full text follows: Considerable recent attention has been focused on the new experiments on measuring the Casimir force. To be confident that experimental data fit theory at a level of several percent, a variety of corrections to the ideal expression for the Casimir force should be taken into account. One of the main corrections at small separations between interacting bodies is the one due to finite conductivity of the boundary metal. This correction has its origin in non-zero penetration depth δ 0 of electromagnetic vacuum oscillations into the metal (for a perfect metal of infinitely large conductivity δ 0 = 0). The other quantity of the dimension of length is the space separation a between two plates or a plate and a sphere. Their relation δ 0 /a is the natural perturbation parameter in which powers the corrections to the Casimir force due to finite conductivity can be expanded. Such an expansion works good for all separations a >> δ 0 (i.e. for separations larger than 100-150 nm). The first-order term of this expansion was calculated almost forty years ago, and the second-order one in 1985 [1]. These two terms are not sufficient for the comparison of the theory with precision modern experiments. In this talk we report the results of paper [2] where the third- and fourth-order terms in δ 0 /a expansion of the Casimir force were calculated first. They gave the possibility to achieve an excellent agreement of a theory and experiment. (author)

  18. Casimir stress in materials: Hard divergency at soft walls

    Science.gov (United States)

    Griniasty, Itay; Leonhardt, Ulf

    2017-11-01

    The Casimir force between macroscopic bodies is well understood, but not the Casimir stress inside bodies. Suppose empty space or a uniform medium meets a soft wall where the refractive index is continuous but its derivative jumps. For this situation we predict a characteristic power law for the stress inside the soft wall and close to its edges. Our result shows that such edges are not tolerated in the aggregation of liquids at surfaces, regardless whether the liquid is attracted or repelled.

  19. A Toy Cosmology Using a Hubble-Scale Casimir Effect

    Directory of Open Access Journals (Sweden)

    Michael E. McCulloch

    2014-02-01

    Full Text Available The visible mass of the observable universe agrees with that needed for a flat cosmos, and the reason for this is not known. It is shown that this can be explained by modelling the Hubble volume as a black hole that emits Hawking radiation inwards, disallowing wavelengths that do not fit exactly into the Hubble diameter, since partial waves would allow an inference of what lies outside the horizon. This model of “horizon wave censorship” is equivalent to a Hubble-scale Casimir effect. This incomplete toy model is presented to stimulate discussion. It predicts a minimum mass and acceleration for the observable universe which are in agreement with the observed mass and acceleration, and predicts that the observable universe gains mass as it expands and was hotter in the past. It also predicts a suppression of variation on the largest cosmic scales that agrees with the low-l cosmic microwave background anomaly seen by the Planck satellite.

  20. Extended Analysis of the Casimir Force

    Directory of Open Access Journals (Sweden)

    Lehnert B.

    2014-04-01

    Full Text Available There are several arguments for the conventional form of the Zero Point Energy fre- quency spectrum to be put in doubt. It has thus to be revised in to that of a self-consistent system in statistical equilibrium where the total energy de nsity and the equivalent pres- sure become finite. An extended form of the Casimir force is th ereby proposed to be used as a tool for determining the local magnitude of the same pressure. This can be done in terms of measurements on the force between a pair po lished plane plates consisting of different metals, the plates having very small or zero air gaps. T his corre- sponds to the largest possible Casimir force. Even then, the re may arise problems with other adhering forces, possibly to be clarified in further experiments.

  1. Thermal Fluctuations in Casimir Pistons

    Science.gov (United States)

    Lomnitz, M.; Villarreal, C.

    2012-07-01

    We present analytical and simple expressions to determine the free energy, internal energy, entropy, as well as the pressure acting at the interface of a perfectly conducting rectangular Casimir piston. We show that infrared divergencies linear in temperature become cancelled within the piston configuration, and show a continuous behavior consistent with intuitive expectations.

  2. Casimir effect at finite temperature for the Kalb-Ramond field

    International Nuclear Information System (INIS)

    Belich, H.; Silva, L. M.; Helayeel-Neto, J. A.; Santana, A. E.

    2011-01-01

    We use the thermofield dynamics formalism to obtain the energy-momentum tensor for the Kalb-Ramond field in a topology S 1 xS 1 xR 2 . The compactification is carried out by a generalized thermofield dynamics-Bogoliubov transformation that is used to define a renormalized energy-momentum tensor. The expressions for the Casimir energy and pressure at finite temperature are then derived. A comparative analysis with the electromagnetic case is developed, and the results may be important for applications, as in cuprate superconductivity, for instance.

  3. Improved tests of extra-dimensional physics and thermal quantum field theory from new Casimir force measurements

    International Nuclear Information System (INIS)

    Decca, R.S.; Fischbach, E.; Klimchitskaya, G.L.; Mostepanenko, V.M.; Krause, D.E.; Lopez, D.

    2003-01-01

    We report new constraints on extra-dimensional models and other physics beyond the standard model based on measurements of the Casimir force between two dissimilar metals for separations in the range 0.2-1.2 μm. The Casimir force between a Au-coated sphere and a Cu-coated plate of a microelectromechanical torsional oscillator was measured statically with an absolute error of 0.3 pN. In addition, the Casimir pressure between two parallel plates was determined dynamically with an absolute error of ≅0.6 mPa. Within the limits of experimental and theoretical errors, the results are in agreement with a theory that takes into account the finite conductivity and roughness of the two metals. The level of agreement between experiment and theory was then used to set limits on the predictions of extra-dimensional physics and thermal quantum field theory. It is shown that two theoretical approaches to the thermal Casimir force which predict effects linear in temperature are ruled out by these experiments. Finally, constraints on Yukawa corrections to Newton's law of gravity are strengthened by more than an order of magnitude in the range 56-330 nm

  4. The generalized Abel-Plana formula with applications to Bessel functions and casimir effect

    International Nuclear Information System (INIS)

    Saharian, Aram A.

    2007-08-01

    One of the most efficient methods for the evaluation of the vacuum expectation values for physical observables in the Casimir effect is based on using the Abel-Plana summation formula. This enables to derive the renormalized quantities in a manifestly cutoff independent way and to present them in the form of strongly convergent integrals. However, applications of the Abel- Plana formula, in its usual form, are restricted by simple geometries when the eigenmodes have a simple dependence on quantum numbers. The author generalized the Abel-Plana formula which essentially enlarges its application range. Based on this generalization, formulae have been obtained for various types of series over the zeros of combinations of Bessel functions and for integrals involving these functions. It has been shown that these results generalize the special cases existing in literature. Further, the derived summation formulae have been used to summarize series arising in the direct mode summation approach to the Casimir effect for spherically and cylindrically symmetric boundaries, for boundaries moving with uniform proper acceleration, and in various braneworld scenarios. This allows to extract from the vacuum expectation values of local physical observables the parts corresponding to the geometry without boundaries and to present the boundary-induced parts in terms of integrals strongly convergent for the points away from the boundaries. As a result, the renormalization procedure for these observables is reduced to the corresponding procedure for bulks without boundaries. The present paper reviews these results. We also aim to collect the results on vacuum expectation values for local physical observables such as the field square and the energy-momentum tensor in manifolds with boundaries for various bulk and boundary geometries. (author)

  5. Membrane actuation by Casimir force manipulation

    International Nuclear Information System (INIS)

    Pinto, Fabrizio

    2008-01-01

    In our laboratory, we have been developing a practical demonstration of actuation by means of the Casimir force inspired by the capacitive detection approach originally described by Arnold, Hunklinger and Dransfeld (1972 Rev. Sci. Instrum. 43 584-7). In this paper, we first describe the mathematical challenges pertaining to the electrostatic calibration of our measuring device, which has been enhanced by our recently published results regarding the computation of electrostatic fields in axial systems, such as the long-standing classical circular capacitor problem. We also discuss our computational approach to the calculation of the Casimir force in our system, including our adoption of analytical descriptions of the dielectric functions of semiconductors extended to the case of axial geometries. We will illustrate how the original AHD apparatus has been drastically improved upon, for instance by means of modern nanopositioner technology, and we shall discuss our published experimental results on the dynamics of a vibrating membrane with a central disc, which have provided the first direct verification of the mechanical resonances of such a system. The emphasis of our effort is not exclusively directed to fundamental physics research but is focused on, and ultimately motivated by, our goal of identifying viable industrial applications leading to commercially marketable products based on Casimir force actuation. Therefore we conclude this paper by briefly discussing the contribution we believe these results will offer to some current technological problems, in particular in nanotechnology, including some thoughts on the possibility that dispersion forces may enable a new and rapidly expanding industry to develop in the near future

  6. Chaotic behavior in Casimir oscillators: A case study for phase-change materials.

    Science.gov (United States)

    Tajik, Fatemeh; Sedighi, Mehdi; Khorrami, Mohammad; Masoudi, Amir Ali; Palasantzas, George

    2017-10-01

    Casimir forces between material surfaces at close proximity of less than 200 nm can lead to increased chaotic behavior of actuating devices depending on the strength of the Casimir interaction. We investigate these phenomena for phase-change materials in torsional oscillators, where the amorphous to crystalline phase transitions lead to transitions between high and low Casimir force and torque states, respectively, without material compositions. For a conservative system bifurcation curve and Poincare maps analysis show the absence of chaotic behavior but with the crystalline phase (high force-torque state) favoring more unstable behavior and stiction. However, for a nonconservative system chaotic behavior can take place introducing significant risk for stiction, which is again more pronounced for the crystalline phase. The latter illustrates the more general scenario that stronger Casimir forces and torques increase the possibility for chaotic behavior. The latter is making it impossible to predict whether stiction or stable actuation will occur on a long-term basis, and it is setting limitations in the design of micronano devices operating at short-range nanoscale separations.

  7. Edge corrections to electromagnetic Casimir energies from general-purpose Mathieu-function routines

    Science.gov (United States)

    Blose, Elizabeth Noelle; Ghimire, Biswash; Graham, Noah; Stratton-Smith, Jeremy

    2015-01-01

    Scattering theory methods make it possible to calculate the Casimir energy of a perfectly conducting elliptic cylinder opposite a perfectly conducting plane in terms of Mathieu functions. In the limit of zero radius, the elliptic cylinder becomes a finite-width strip, which allows for the study of edge effects. However, existing packages for computing Mathieu functions are insufficient for this calculation because none can compute Mathieu functions of both the first and second kind for complex arguments. To address this shortcoming, we have written a general-purpose Mathieu-function package, based on algorithms developed by Alhargan. We use these routines to find edge corrections to the proximity force approximation for the Casimir energy of a perfectly conducting strip opposite a perfectly conducting plane.

  8. Scalar Casimir energies in M4≥/sup N/ for even N

    International Nuclear Information System (INIS)

    Kantowski, R.; Milton, K.A.

    1987-01-01

    We construct a Green's-function formalism for computing vacuum-fluctuation energies of scalar fields in 4+N dimensions, where the extra N dimensions are compactified into a hypersphere S/sup N/ of radius a. In all cases a leading cosmological energy term u/sub cosmo/proportionala/sup N//b/sup 4+N/ results. Here b is an ultraviolet cutoff at the Planck scale. In all cases an unambiguous Casimir energy is computed. For odd N these energies agree with those calculated by Candelas and Weinberg. For even N, the Casimir energy is logarithmically divergent: u/sub Casimir/--(α/sub N//a 4 )ln(a/b). The coefficients α/sub N/ are computed in terms of Bernoulli numbers

  9. Quest for Casimir repulsion between Chern-Simons surfaces

    Science.gov (United States)

    Fialkovsky, Ignat; Khusnutdinov, Nail; Vassilevich, Dmitri

    2018-04-01

    In this paper we critically reconsider the Casimir repulsion between surfaces that carry the Chern-Simons interaction (corresponding to the Hall-type conductivity). We present a derivation of the Lifshitz formula valid for arbitrary planar geometries and discuss its properties. This analysis allows us to resolve some contradictions in the previous literature. We compute the Casimir energy for two surfaces that have constant longitudinal and Hall conductivities. The repulsion is possible only if both surfaces have Hall conductivities of the same sign. However, there is a critical value of the longitudinal conductivity above which the repulsion disappears. We also consider a model where both parity odd and parity even terms in the conductivity are produced by the polarization tensor of surface modes. In contrast to the previous publications [L. Chen and S.-L. Wan, Phys. Rev. B 84, 075149 (2011), 10.1103/PhysRevB.84.075149; Phys. Rev. B 85, 115102 (2012), 10.1103/PhysRevB.85.115102], we include the parity anomaly term. This term ensures that the conductivities vanish for infinitely massive surface modes. We find that at least for a single mode, regardless of the sign and value of its mass, there is no Casimir repulsion.

  10. Casimir effect at finite temperature for pure-photon sector of the minimal Standard Model Extension

    Energy Technology Data Exchange (ETDEWEB)

    Santos, A.F., E-mail: alesandroferreira@fisica.ufmt.br [Instituto de Física, Universidade Federal de Mato Grosso, 78060-900, Cuiabá, Mato Grosso (Brazil); Department of Physics and Astronomy, University of Victoria, 3800 Finnerty Road Victoria, BC (Canada); Khanna, Faqir C., E-mail: khannaf@uvic.ca [Department of Physics and Astronomy, University of Victoria, 3800 Finnerty Road Victoria, BC (Canada)

    2016-12-15

    Dynamics between particles is governed by Lorentz and CPT symmetry. There is a violation of Parity (P) and CP symmetry at low levels. The unified theory, that includes particle physics and quantum gravity, may be expected to be covariant with Lorentz and CPT symmetry. At high enough energies, will the unified theory display violation of any symmetry? The Standard Model Extension (SME), with Lorentz and CPT violating terms, has been suggested to include particle dynamics. The minimal SME in the pure photon sector is considered in order to calculate the Casimir effect at finite temperature.

  11. Casimir Energy of Rotating String --- Indirect Approach

    Science.gov (United States)

    Hadasz, Leszek

    1999-04-01

    Methods of calculating the Casimir energy which do not require the explicit knowledge of the oscillation frequencies are developed and applied to the model of the Nambu--Goto string with the Gauss--Bonnet term in the action.

  12. Towards measurement of the Casimir force between parallel plates separated at sub-mircon distance

    NARCIS (Netherlands)

    Syed Nawazuddin, M.B.; Lammerink, Theodorus S.J.; Wiegerink, Remco J.; Berenschot, Johan W.; de Boer, Meint J.; Elwenspoek, Michael Curt

    2011-01-01

    Ever since its prediction, experimental investigation of the Casimir force has been of great scientific interest. Many research groups have successfully attempted quantifying the force with different device geometries; however measurement of the Casimir force between parallel plates with sub-micron

  13. The Casimir interaction of a massive vector field between concentric spherical bodies

    International Nuclear Information System (INIS)

    Teo, L.P.

    2011-01-01

    The Casimir interaction energy due to the vacuum fluctuations of a massive vector field between two perfectly conducting concentric spherical bodies is computed. The TE contribution to the Casimir interaction energy is a direct generalization of the massless case but the TM contribution is much more complicated. Each TM mode is a linear combination of a transverse mode which is the generalization of a TM mode in the massless case and a longitudinal mode that does not appear in the massless case. In contrast to the case of two parallel perfectly conducting plates, there are no TM discrete modes that vanish identically in the perfectly conducting spherical bodies. Numerical simulations show that the Casimir interaction force between the two bodies is always attractive.

  14. Roughness corrections to the Casimir force : The importance of local surface slope

    NARCIS (Netherlands)

    van Zwol, P. J.; Palasantzas, G.; De Hosson, J. Th. M.

    2007-01-01

    This paper concentrates on a study where finite conductivity corrections are included in the theoretical description of the effects of roughness on the Casimir force. The roughness data were taken from gold films evaporated onto silicon and polysterene spheres. We conclude that for a detailed

  15. Casimir energy of rotating string - indirect approach

    International Nuclear Information System (INIS)

    Hadasz, L.

    1999-01-01

    Methods of calculating the Casimir energy which do not require the explicit knowledge of the oscillation frequencies are developed and applied to the model of the Nambu-Goto string with the Gauss-Bonnet term in the action. (author)

  16. Casimir apparatuses in a weak gravitational field

    DEFF Research Database (Denmark)

    Bimonte, Giuseppe; Calloni, Enrico; Esposito, Giampiero

    2009-01-01

    We review and assess a part of the recent work on Casimir apparatuses in the weak gravitational field of the Earth. For a free, real massless scalar field subject to Dirichlet or Neumann boundary conditions on the parallel plates, the resulting regularized and renormalized energy-momentum tensor...... is covariantly conserved, while the trace anomaly vanishes if the massless field is conformally coupled to gravity. Conformal coupling also ensures a finite Casimir energy and finite values of the pressure upon parallel plates. These results have been extended to an electromagnetic field subject to perfect...... conductor (hence idealized) boundary conditions on parallel plates, by various authors. The regularized and renormalized energy-momentum tensor has beene valuated up to second order in the gravity acceleration. In both the scalar and the electromagnetic case, studied to first order in the gravity...

  17. A Light Sail Inspired Model to Harness Casimir Forces for Propellantless Propulsion

    International Nuclear Information System (INIS)

    DeBiase, R. L.

    2010-01-01

    The model used to calculate Casimir forces for variously shaped conducting plates in this paper assumes the vacuum energy pervades all space and that photons randomly pop into and out of existence. While they exist, they possess energy and momentum that can be transferred by reflection as in a light sail. Quantum mechanics in the model is entirely bound up in the Casimir equation of force per unit area. This model is compared with two different experiments: that of Chen and Mohideen demonstrating lateral Casimir forces for sinusoidally corrugated spherical and flat plates and Lamoreaux demonstrating normal Casimir forces between a conducting sphere and flat plate. The calculated forces using this model were compared to the forces obtained in these experiments as well as with calculations using the proximity force approximation. In both cases the results (when compared to the actual plates measured and calculated using non-corrected equations) were less than a few parts per thousand different for the range of separation distances used. When the model was used to calculate forces on the opposite plates, different force magnitudes were obtained seemingly indicating prospects for propellentless propulsion but requiring skeptical verification.

  18. Reply to 'Comment on 'Temperature dependence of the Casimir force for lossy bulk media''

    Energy Technology Data Exchange (ETDEWEB)

    Yampol' skii, V. A.; Maizelis, Z. A.; Apostolov, S. S. [Advanced Science Institute, RIKEN, Saitama, 351-0198 (Japan); A. Ya. Usikov Institute for Radiophysics and Electronics, NASU, 61085 Kharkov (Ukraine); Savel' ev, Sergey [Advanced Science Institute, RIKEN, Saitama, 351-0198 (Japan); Department of Physics, Loughborough University, Loughborough LE11 3TU (United Kingdom); Nori, Franco [Advanced Science Institute, RIKEN, Saitama, 351-0198 (Japan); Department of Physics, University of Michigan, Ann Arbor, Michigan 48109 (United States)

    2011-09-15

    Here, we present an estimate of the characteristic wavelengths of the evanescent modes, which define the main contribution to the thermal part of the Casimir force. This estimate is more precise than the one in the preceding Comment by Bimonte et al.[Phys. Rev. A 84, 036501 (2011)]. The wavelengths we derive are indeed smaller than the sizes of the interacting bodies. We also discuss the results of several experiments on the thermal effects in the Casimir force.

  19. Tunable Stable Levitation Based on Casimir Interaction between Nanostructures

    Science.gov (United States)

    Liu, Xianglei; Zhang, Zhuomin M.

    2016-03-01

    Quantum levitation enabled by repulsive Casimir force has been desirable due to the potential exciting applications in passive-suspension devices and frictionless bearings. In this paper, dynamically tunable stable levitation is theoretically demonstrated based on the configuration of dissimilar gratings separated by an intervening fluid using exact scattering theory. The levitation position is insensitive to temperature variations and can be actively tuned by adjusting the lateral displacement between the two gratings. This work investigates the possibility of applying quantum Casimir interactions into macroscopic mechanical devices working in a noncontact and low-friction environment for controlling the position or transducing lateral movement into vertical displacement at the nanoscale.

  20. Topological Casimir effect in compactified cosmic string spacetime

    International Nuclear Information System (INIS)

    De Mello, E R Bezerra; Saharian, A A

    2012-01-01

    We investigate the Wightman function, the vacuum expectation values of the field squared and the energy-momentum tensor for a massive scalar field with general curvature coupling in the generalized cosmic string geometry with a compact dimension along its axis. The boundary condition along the compactified dimension is taken in general form with an arbitrary phase. The vacuum expectation values are decomposed into two parts. The first one corresponds to the uncompactified cosmic string geometry and the second one is the correction induced by the compactification. The asymptotic behavior of the vacuum expectation values of the field squared, energy density and stresses is investigated near the string and at large distances. We show that the nontrivial topology due to the cosmic string enhances the vacuum polarization effects induced by the compactness of spatial dimension for both the field squared and the vacuum energy density. A simple formula is given for the part of the integrated topological Casimir energy induced by the planar angle deficit. The results are generalized for a charged scalar field in the presence of a constant gauge field. In this case, the vacuum expectation values are periodic functions of the component of the vector potential along the compact dimension. (paper)

  1. Casimir energy of rotating string - indirect approach

    Energy Technology Data Exchange (ETDEWEB)

    Hadasz, L. [Smoluchowski Institute of Physics, Jagiellonian University, Cracow (Poland)

    1999-04-01

    Methods of calculating the Casimir energy which do not require the explicit knowledge of the oscillation frequencies are developed and applied to the model of the Nambu-Goto string with the Gauss-Bonnet term in the action. (author) 17 refs, 1 fig

  2. Casimir-Lifshitz force out of thermal equilibrium

    NARCIS (Netherlands)

    Antezza, M.; Pitaevskii, L.P.; Stringari, S.; Svetovoy, Vitaly

    We study the Casimir-Lifshitz interaction out of thermal equilibrium, when the interacting objects are at different temperatures. The analysis is focused on the surface-surface, surface-rarefied body, and surface-atom configurations. A systematic investigation of the contributions to the force

  3. Casimir energy for a piecewise uniform string

    International Nuclear Information System (INIS)

    Brevik, I.; Nielsen, H.B.

    1989-07-01

    The Casimir energy for the transverse oscillations of a piecewise uniform closed string is calculated. The string consists of two parts I and II, endowed in general with different tensions and mass densities, although adjusted in such a way that the velocity of sound always equals the velocity of light. The dispersion equation is worked out under general conditions, and the frequency spectrum is determined in special cases. When the ratio L II /L I between the string lengths is an integer, it is in principle possible to determine the frequency spectrum through solving algebraic equations of increasingly high degree. The Casimir energy relative to the uniform string is in general found to be negative, although in the special case L I =L II the energy is equal to zero. Delicate points in the regularization procedure are discussed; they point toward an anomaly in the theory. (orig.)

  4. Casimir-Polder potential for a metallic cylinder in cosmic string spacetime

    Energy Technology Data Exchange (ETDEWEB)

    Saharian, A.A., E-mail: saharian@ysu.am [Department of Physics, Yerevan State University, 1 Alex Manoogian Street, 0025 Yerevan (Armenia); Kotanjyan, A.S. [Department of Physics, Yerevan State University, 1 Alex Manoogian Street, 0025 Yerevan (Armenia)

    2012-07-09

    Casimir-Polder potential is investigated for a polarizable microparticle in the geometry of a straight cosmic string with a metallic cylindrical shell. The electromagnetic field Green tensor is evaluated on the imaginary frequency axis. The expressions for the Casimir-Polder potential is derived in the general case of anisotropic polarizability for the both interior and exterior regions of the shell. The potential is decomposed into pure string and shell-induced parts. The latter dominates for points near the shell, whereas the pure string part is dominant near the string and at large distances from the shell. For the isotropic case and in the region inside the shell the both pure string and shell-induced parts in the Casimir-Polder force are repulsive with respect to the string. In the exterior region the shell-induced part of the force is directed toward the cylinder whereas the pure string part remains repulsive with respect to the string. At large distances from the shell the total force is repulsive.

  5. Rigorous approach to the comparison between experiment and theory in Casimir force measurements

    International Nuclear Information System (INIS)

    Klimchitskaya, G L; Chen, F; Decca, R S; Fischbach, E; Krause, D E; Lopez, D; Mohideen, U; Mostepanenko, V M

    2006-01-01

    In most experiments on the Casimir force the comparison between measurement data and theory was done using the concept of the root-mean-square deviation, a procedure that has been criticized in the literature. Here we propose a special statistical analysis which should be performed separately for the experimental data and for the results of the theoretical computations. In so doing, the random, systematic and total experimental errors are found as functions of separation, taking into account the distribution laws for each error at 95% confidence. Independently, all theoretical errors are combined to obtain the total theoretical error at the same confidence. Finally, the confidence interval for the differences between theoretical and experimental values is obtained as a function of separation. This rigorous approach is applied to two recent experiments on the Casimir effect

  6. Casimir amplitudes in topological quantum phase transitions.

    Science.gov (United States)

    Griffith, M A; Continentino, M A

    2018-01-01

    Topological phase transitions constitute a new class of quantum critical phenomena. They cannot be described within the usual framework of the Landau theory since, in general, the different phases cannot be distinguished by an order parameter, neither can they be related to different symmetries. In most cases, however, one can identify a diverging length at these topological transitions. This allows us to describe them using a scaling approach and to introduce a set of critical exponents that characterize their universality class. Here we consider some relevant models of quantum topological transitions associated with well-defined critical exponents that are related by a quantum hyperscaling relation. We extend to these models a finite-size scaling approach based on techniques for calculating the Casimir force in electromagnetism. This procedure allows us to obtain universal Casimir amplitudes at their quantum critical points. Our results verify the validity of finite-size scaling in these systems and confirm the values of the critical exponents obtained previously.

  7. Effective field theory of thermal Casimir interactions between anisotropic particles.

    Science.gov (United States)

    Haussman, Robert C; Deserno, Markus

    2014-06-01

    We employ an effective field theory (EFT) approach to study thermal Casimir interactions between objects bound to a fluctuating fluid surface or interface dominated by surface tension, with a focus on the effects of particle anisotropy. The EFT prescription disentangles the constraints imposed by the particles' boundaries from the calculation of the interaction free energy by constructing an equivalent point particle description. The finite-size information is captured in a derivative expansion that encodes the particles' response to external fields. The coefficients of the expansion terms correspond to generalized tensorial polarizabilities and are found by matching the results of a linear response boundary value problem computed in both the full and effective theories. We demonstrate the versatility of the EFT approach by constructing the general effective Hamiltonian for a collection of particles of arbitrary shapes. Taking advantage of the conformal symmetry of the Hamiltonian, we discuss a straightforward conformal mapping procedure to systematically determine the polarizabilities and derive a complete description for elliptical particles. We compute the pairwise interaction energies to several orders for nonidentical ellipses as well as their leading-order triplet interactions and discuss the resulting preferred pair and multibody configurations. Furthermore, we elaborate on the complications that arise with pinned particle boundary conditions and show that the powerlike corrections expected from dimensional analysis are exponentially suppressed by the leading-order interaction energies.

  8. Casimir energy between two parallel plates and projective representation of the Poincaré group

    Science.gov (United States)

    Akita, Takamaru; Matsunaga, Mamoru

    2016-06-01

    The Casimir effect is a physical manifestation of zero point energy of quantum vacuum. In a relativistic quantum field theory, Poincaré symmetry of the theory seems, at first sight, to imply that nonzero vacuum energy is inconsistent with translational invariance of the vacuum. In the setting of two uniform boundary plates at rest, quantum fields outside the plates have (1 +2 )-dimensional Poincaré symmetry. Taking a massless scalar field as an example, we have examined the consistency between the Poincaré symmetry and the existence of the vacuum energy. We note that, in quantum theory, symmetries are represented projectively in general and show that the Casimir energy is connected to central charges appearing in the algebra of generators in the projective representations.

  9. Generalized Ford-Vilenkin approach for the dynamical Casimir effect

    International Nuclear Information System (INIS)

    Rego, Andreson L.C.; Alves, Danilo Teixeira; Alves, Joao Paulo da Silva

    2012-01-01

    Full text: In the 70s decade the first works investigating the quantum problem of the radiation emitted by moving mirrors in vacuum were published by Moore, DeWitt, Fulling and Davies. This effect, usually named dynamical Casimir effect (DCE). The DCE is also related to several other problems like particle creation in cosmological models and radiation emitted by collapsing black holes, decoherence, entanglement the Unruh effect. The DCE has been subject to experimental investigations: few months ago, Wilson and collaborators have announced the first experimental observation of the DCE. The theory of the DCE has been investigated by many authors, among them Ford and Vilenkin [L.H. Ford and A. Vilenkin, Phys. Rev. D 25, 2569 (1982)] who developed a perturbative method, which can be applied to moving mirrors in small displacements δq(t) = εF (t) and with nonrelativistic velocities. The usual application of the Ford-Vilenkin approach to the calculation of the spectrum of the created particles, results in the spectral distribution proportional to ε 2 . In the present paper, we consider a real massless scalar field and a moving mirror in a two-dimensional spacetime, satisfying Dirichlet boundary condition at the instantaneous position of the mirror, for large displacements and relativistic velocities. We generalize the Ford-Vilenkin approach to the calculation of the spectral density of the created particles, obtaining formulas for the spectrum up to order ε n . (author)

  10. Casimir energy of a nonuniform string

    Science.gov (United States)

    Hadasz, L.; Lambiase, G.; Nesterenko, V. V.

    2000-07-01

    The Casimir energy of a nonuniform string built up from two pieces with different speeds of sound is calculated. A standard procedure of subtracting the energy of an infinite uniform string is applied, the subtraction being interpreted as the renormalization of the string tension. It is shown that in the case of a homogeneous string this method is completely equivalent to zeta renormalization.

  11. Casimir friction and near-field radiative heat transfer in graphene structures

    Energy Technology Data Exchange (ETDEWEB)

    Volokitin, A.I. [Forschungszentrum Juelich (Germany). Peter Gruenberg Inst.; Samara State Technical Univ. (Russian Federation). Physical Dept.

    2017-05-01

    The dependence of the Casimir friction force between a graphene sheet and a (amorphous) SiO{sub 2} substrate on the drift velocity of the electrons in the graphene sheet is studied. It is shown that the Casimir friction is strongly enhanced for the drift velocity above the threshold velocity when the friction is determined by the resonant excitation of the surface phonon-polaritons in the SiO{sub 2} substrate and the electron-hole pairs in graphene. The theory agrees well with the experimental data for the current-voltage dependence for unsuspended graphene on the SiO{sub 2} substrate. The theories of the Casimir friction and the near-field radiative energy transfer are used to study the heat generation and dissipation in graphene due to the interaction with phonon-polaritons in the (amorphous) SiO{sub 2} substrate and acoustic phonons in graphene. For suspended graphene, the energy transfer coefficient at nanoscale gap is ∝ three orders of magnitude larger than the radiative heat transfer coefficient of the blackbody radiation limit.

  12. Casimir friction and near-field radiative heat transfer in graphene structures

    International Nuclear Information System (INIS)

    Volokitin, A.I.; Samara State Technical Univ.

    2017-01-01

    The dependence of the Casimir friction force between a graphene sheet and a (amorphous) SiO 2 substrate on the drift velocity of the electrons in the graphene sheet is studied. It is shown that the Casimir friction is strongly enhanced for the drift velocity above the threshold velocity when the friction is determined by the resonant excitation of the surface phonon-polaritons in the SiO 2 substrate and the electron-hole pairs in graphene. The theory agrees well with the experimental data for the current-voltage dependence for unsuspended graphene on the SiO 2 substrate. The theories of the Casimir friction and the near-field radiative energy transfer are used to study the heat generation and dissipation in graphene due to the interaction with phonon-polaritons in the (amorphous) SiO 2 substrate and acoustic phonons in graphene. For suspended graphene, the energy transfer coefficient at nanoscale gap is ∝ three orders of magnitude larger than the radiative heat transfer coefficient of the blackbody radiation limit.

  13. Resolution of an apparent inconsistency in the electromagnetic Casimir effect

    International Nuclear Information System (INIS)

    Alnes, H; Olaussen, K; Ravndal, F; Wehus, I K

    2007-01-01

    The vacuum expectation value of the electromagnetic energy-momentum tensor between two parallel plates in spacetime dimensions D > 4 is calculated in the axial gauge. While the pressure between the plates agrees with the global Casimir force, the energy density is divergent at the plates and not compatible with the total energy which follows from the force. However, subtracting the divergent self-energies of the plates, the resulting energy is finite and consistent with the force. In analogy with the corresponding scalar case for spacetime dimensions D > 2, the divergent self-energy of a single plate can be related to the lack of conformal invariance of the electromagnetic Lagrangian for dimensions D > 4. (fast track communication)

  14. Beyond-proximity-force-approximation Casimir force between two spheres at finite temperature

    Science.gov (United States)

    Bimonte, Giuseppe

    2018-04-01

    A recent experiment [J. L. Garrett, D. A. T. Somers, and J. N. Munday, Phys. Rev. Lett. 120, 040401 (2018), 10.1103/PhysRevLett.120.040401] measured for the first time the gradient of the Casimir force between two gold spheres at room temperature. The theoretical analysis of the data was carried out using the standard proximity force approximation (PFA). A fit of the data, using a parametrization of the force valid for the sphere-plate geometry, was used by the authors to place a bound on deviations from PFA. Motivated by this work, we compute the Casimir force between two gold spheres at finite temperature. The semianalytic formula for the Casimir force that we construct is valid for all separations, and can be easily used to interpret future experiments in both the sphere-plate and sphere-sphere configurations. We describe the correct parametrization of the corrections to PFA for two spheres that should be used in data analysis.

  15. Casimir-Lifshitz force for nonreciprocal media and applications to photonic topological insulators

    Science.gov (United States)

    Fuchs, Sebastian; Lindel, Frieder; Krems, Roman V.; Hanson, George W.; Antezza, Mauro; Buhmann, Stefan Yoshi

    2017-12-01

    Based on the theory of macroscopic quantum electrodynamics, we generalize the expression of the Casimir force for nonreciprocal media. The essential ingredient of this result is the Green's tensor between two nonreciprocal semi-infinite slabs, including a reflexion matrix with four coefficients that mixes optical polarizations. This Green's tensor does not obey Lorentz's reciprocity and thus violates time-reversal symmetry. The general result for the Casimir force is analyzed in the retarded and nonretarded limits, concentrating on the influences arising from reflections with or without change of polarization. In a second step, we apply our general result to a photonic topological insulator whose nonreciprocity stems from an anisotropic permittivity tensor, namely InSb. We show that there is a regime for the distance between the slabs where the magnitude of the Casimir force is tunable by an external magnetic field. Furthermore, the strength of this tuning depends on the orientation of the magnetic field with respect to the slab surfaces.

  16. Optical properties of gold films and the Casimir force

    International Nuclear Information System (INIS)

    Svetovoy, V. B.; Zwol, P. J. van; Palasantzas, G.; De Hosson, J. Th. M.

    2008-01-01

    Precise optical properties of metals are very important for accurate prediction of the Casimir force acting between two metallic plates. Therefore we measured ellipsometrically the optical responses of Au films in a wide range of wavelengths from 0.14 to 33 μm. The films at various thicknesses were deposited at different conditions on silicon or mica substrates. Considerable variation of the frequency dependent dielectric function from sample to sample was found. Detailed analysis of the dielectric functions was performed to check the Kramers-Kronig consistency, and extract the Drude parameters of the films. It was found that the plasma frequency varies in the range from 6.8 to 8.4 eV. It is suggested that this variation is related with the film density. X-ray reflectivity measurements support qualitatively this conclusion. The Casimir force is evaluated for the dielectric functions corresponding to our samples, and for that typically used in the precise prediction of the force. The force for our films was found to be 5%-14% smaller at a distance of 100 nm between the plates. Noise in the optical data is responsible for the force variation within 1%. It is concluded that prediction of the Casimir force between metals with a precision better than 10% must be based on the material optical response measured from visible to mid-infrared range

  17. Casimir interaction between a cylinder and a plate at finite temperature: Exact results and comparison to proximity force approximation

    International Nuclear Information System (INIS)

    Teo, L. P.

    2011-01-01

    We study the finite temperature Casimir interaction between a cylinder and a plate using the exact formula derived from the Matsubara representation and the functional determinant representation. We consider the scalar field with Dirichlet and Neumann boundary conditions. The asymptotic expansions of the Casimir free energy and the Casimir force when the separation a between the cylinder and the plate is small are derived. As in the zero temperature case, it is found that the leading terms of the Casimir free energy and the Casimir force agree with those derived from the proximity force approximation when rT>>1, where r is the radius of the cylinder. Specifically, when aT 5/2 whereas, for the Casimir force, it is of order T 7/2 . In this case, the leading terms are independent of the separation a. When 1 3/2 , whereas, for the force, it is inversely proportional to a 5/2 . The first order corrections to the proximity force approximations in different temperature regions are computed using the perturbation approach. In the zero temperature case, the results agree with those derived in [M. Bordag, Phys. Rev. D 73, 125018 (2006)].

  18. Selective decay by Casimir dissipation in inviscid fluids

    International Nuclear Information System (INIS)

    Gay-Balmaz, François; Holm, Darryl D

    2013-01-01

    The problem of parameterizing the interactions of larger scales and smaller scales in fluid flows is addressed by considering a property of two-dimensional (2D) incompressible turbulence. The property we consider is selective decay, in which a Casimir of the ideal formulation (enstrophy in 2D flows, helicity in three-dimensional flows) decays in time, while the energy stays essentially constant. This paper introduces a mechanism that produces selective decay by enforcing Casimir dissipation in fluid dynamics. This mechanism turns out to be related in certain cases to the numerical method of anticipated vorticity discussed in Sadourny and Basdevant (1981 C. R. Acad. Sci. Paris 292 1061–4, 1985 J. Atm. Sci. 42 1353–63). Several examples are given and a general theory of selective decay is developed that uses the Lie–Poisson structure of the ideal theory. A scale-selection operator allows the resulting modifications of the fluid motion equations to be interpreted in several examples as parametrizing the nonlinear, dynamical interactions between disparate scales. The type of modified fluid equation systems derived here may be useful in modelling turbulent geophysical flows where it is computationally prohibitive to rely on the slower, indirect effects of a realistic viscosity, such as in large-scale, coherent, oceanic flows interacting with much smaller eddies. (paper)

  19. Critical Steps in Data Analysis for Precision Casimir Force Measurements with Semiconducting Films

    Science.gov (United States)

    Banishev, A. A.; Chang, Chia-Cheng; Mohideen, U.

    2011-06-01

    Some experimental procedures and corresponding results of the precision measurement of the Casimir force between low doped Indium Tin Oxide (ITO) film and gold sphere are described. Measurements were performed using an Atomic Force Microscope in high vacuum. It is shown that the magnitude of the Casimir force decreases after prolonged UV treatment of the ITO film. Some critical data analysis steps such as the correction for the mechanical drift of the sphere-plate system and photodiodes are discussed.

  20. Tuning the Mass of Chameleon Fields in Casimir Force Experiments

    CERN Document Server

    Brax, Ph; Davis, A C; Shaw, D J; Iannuzzi, D

    2010-01-01

    We have calculated the chameleon pressure between two parallel plates in the presence of an intervening medium that affects the mass of the chameleon field. As intuitively expected, the gas in the gap weakens the chameleon interaction mechanism with a screening effect that increases with the plate separation and with the density of the intervening medium. This phenomenon might open up new directions in the search of chameleon particles with future long range Casimir force experiments.

  1. The analytic regularization ζ function method and the cut-off method in Casimir effect

    International Nuclear Information System (INIS)

    Svaiter, N.F.; Svaiter, B.F.

    1990-01-01

    The zero point energy associated to a hermitian massless scalar field in the presence of perfectly reflecting plates in a three dimensional flat space-time is discussed. A new technique to unify two different methods - the ζ function and a variant of the cut-off method - used to obtain the so called Casimir energy is presented, and the proof of the analytic equivalence between both methods is given. (author)

  2. Symmetries and casimir of an extended classical long wave system

    Indian Academy of Sciences (India)

    Keywords. Dispersionless equations; symmetries; casimir; conserved quantities. ... Application of Lie symmetry analysis to integro-differential equations or infinite systems ..... The financial support in the form of Senior Research Fellowship.

  3. Casimir force in the Goedel space-time and its possible induced cosmological inhomogeneity

    Energy Technology Data Exchange (ETDEWEB)

    Khodabakhshi, Sh. [University of Tehran, Department of Physics, Tehran (Iran, Islamic Republic of); Shojai, A. [University of Tehran, Department of Physics, Tehran (Iran, Islamic Republic of); Institute for Research in Fundamental Sciences (IPM), Foundations of Physics Group, School of Physics, Tehran (Iran, Islamic Republic of)

    2017-07-15

    The Casimir force between two parallel plates in the Goedel universe is computed for a scalar field at finite temperature. It is observed that when the plates' separation is comparable with the scale given by the rotation of the space-time, the force becomes repulsive and then approaches zero. Since it has been shown previously that the universe may experience a Goedel phase for a small period of time, the induced inhomogeneities from the Casimir force are also studied. (orig.)

  4. Free vibration of geometrically nonlinear micro-switches under electrostatic and Casimir forces

    International Nuclear Information System (INIS)

    Jia, X L; Kitipornchai, S; Lim, C W; Yang, J

    2010-01-01

    This paper investigates the free vibration characteristics of micro-switches under combined electrostatic, intermolecular forces and axial residual stress, with an emphasis on the effect of geometric nonlinear deformation due to mid-plane stretching and the influence of Casimir force. The micro-switch considered in this study is made of either homogeneous material or non-homogeneous functionally graded material with two material phases. The Euler–Bernoulli beam theory with von Karman type nonlinear kinematics is applied in the theoretical formulation. The principle of virtual work is used to derive the nonlinear governing differential equation. The eigenvalue problem which describes free vibration of the micro-beam at its statically deflected state is then solved using the differential quadrature method. The natural frequencies and mode shapes of micro-switches for four different boundary conditions (i.e. clamped–clamped, clamped–simply supported, simply supported and clamped–free) are obtained. The solutions are validated through direct comparisons with experimental and other existing results reported in previous studies. A parametric study is conducted to show the significant effects of geometric nonlinearity, Casimir force, axial residual stress and material composition for the natural frequencies

  5. Casimir energies in M4≥/sup N/ for even N. Green's-function and zeta-function techniques

    International Nuclear Information System (INIS)

    Kantowski, R.; Milton, K.A.

    1987-01-01

    The Green's-function technique developed in the first paper in this series is generalized to apply to massive scalar, vector, second-order tensor, and Dirac spinor fields, as a preliminary to a full graviton calculation. The Casimir energies are of the form u/sub Casimir/ = (1/a 4 )[α/sub N/lna/b)+β/sub N/], where N (even) is the dimension of the internal sphere, a is its radius, and b/sup -1/ is an ultraviolet cutoff (presumably at the Planck scale). The coefficient of the divergent logarithm, α/sub N/, is unambiguously obtained for each field considered. The Green's-function technique gives rise to no difficulties in the evaluation of imaginary-mass-mode contributions to the Casimir energy. In addition, a new, simplified zeta-function technique is presented which is very easily implemented by symbolic programs, and which, of course, gives the same results. An error in a previous zeta-function calculation of the Casimir energy for even N is pointed out

  6. The Casimir effect in rugby-ball type flux compactifications

    International Nuclear Information System (INIS)

    Minamitsuji, M

    2008-01-01

    We discuss volume stabilization in a 6D braneworld model based on 6D supergravity theory. The internal space is compactified by magnetic flux and contains codimension two 3-branes (conical singularities) as its boundaries. In general the external 4D spacetime is warped and in the unwrapped limit the shape of the internal space looks like a 'rugby ball'. The size of the internal space is not fixed due to the scale invariance of the supergravity theory. We discuss the possibility of volume stabilization by the Casimir effect for a massless, minimally coupled bulk scalar field. The main obstacle in studying this case is that the brane (conical) part of the relevant heat kernel coefficient (a 6 ) has not been formulated. Thus as a first step, we consider the 4D analog model with boundary codimension two 1-branes. The spacetime structure of the 4D model is very similar to that of the original 6D model, where now the relevant heat kernel coefficient is well known. We derive the one-loop effective potential induced by a scalar field in the bulk by employing zeta function regularization with heat kernel analysis. As a result, the volume is stabilized for most possible choices of the parameters. Especially, for a larger degree of warping, our results imply that a large hierarchy between the mass scales and a tiny amount of effective cosmological constant can be realized on the brane. In the non-warped limit the ratio tends to converge to the same value, independently of the bulk gauge coupling constant. Finally, we will analyze volume stabilization in the original model 6D by employing the same mode-sum technique

  7. Eigenvalues of Casimir operators for the general linear, the special linear, and the orthosymplectic Lie superalgebras

    International Nuclear Information System (INIS)

    Scheunert, M.

    1982-10-01

    The generators of the algebras under consideration can be written in a canonical two-index form and hence the associated standard seuqence of Casimir elements can be constructed. Following the classical approach by Perelomov and Popov, we obtain the eigenvalues of these Casimir elements in an arbitrary highest weight module by calculating the corresponding generating functions. (orig.)

  8. Recent breakthrough and outlook in constraining the non-Newtonian gravity and axion-like particles from Casimir physics

    Energy Technology Data Exchange (ETDEWEB)

    Klimchitskaya, G.L. [Central Astronomical Observatory at Pulkovo of the Russian Academy of Sciences, Saint Petersburg (Russian Federation); Peter the Great Saint Petersburg Polytechnic University, Institute of Physics, Nanotechnology and Telecommunications, Saint Petersburg (Russian Federation)

    2017-05-15

    The strongest constraints on the Yukawa-type corrections to Newton's gravitational law and on the coupling constants of axion-like particles to nucleons, following from recently performed experiments of Casimir physics, are presented. Specifically, the constraints obtained from measurements of the lateral and normal Casimir forces between sinusoidally corrugated surfaces, and from the isoelectronic experiment are considered, and the ranges of their greatest strength are refined. Minor modifications in the experimental setups are proposed which allow for strengthening the resultant constraints up to an order of magnitude. The comparison with some weaker constraints derived in the Casimir regime is also made. (orig.)

  9. Development of a Strontium Magneto-Optical Trap for Probing Casimir-Polder Potentials

    Science.gov (United States)

    Martin, Paul J.

    In recent years, cold atoms have been the centerpiece of many remarkably sensitive measurements, and much effort has been made to devise miniaturized quantum sensors and quantum information processing devices. At small distances, however, mechanical effects of the quantum vacuum begin to significantly impact the behavior of the cold-atom systems. A better understanding of how surface composition and geometry affect Casimir and Casimir-Polder potentials would benefit future engineering of small-scale devices. Unfortunately, theoretical solutions are limited and the number of experimental techniques that can accurately detect such short-range forces is relatively small. We believe the exemplary properties of atomic strontium--which have enabled unprecedented frequency metrology in optical lattice clocks--make it an ideal candidate for probing slight spectroscopic perturbations caused by vacuum fluctuations. To that end, we have constructed a magneto-optical trap for strontium to enable future study of atom-surface potentials, and the apparatus and proposed detection scheme are discussed herein. Of special note is a passively stable external-cavity diode laser we developed that is both affordable and competitive with high-end commercial options.

  10. The stochastic energy-Casimir method

    Science.gov (United States)

    Arnaudon, Alexis; Ganaba, Nader; Holm, Darryl D.

    2018-04-01

    In this paper, we extend the energy-Casimir stability method for deterministic Lie-Poisson Hamiltonian systems to provide sufficient conditions for stability in probability of stochastic dynamical systems with symmetries. We illustrate this theory with classical examples of coadjoint motion, including the rigid body, the heavy top, and the compressible Euler equation in two dimensions. The main result is that stable deterministic equilibria remain stable in probability up to a certain stopping time that depends on the amplitude of the noise for finite-dimensional systems and on the amplitude of the spatial derivative of the noise for infinite-dimensional systems. xml:lang="fr"

  11. The Casimir effect in rugby-ball type flux compactifications

    Energy Technology Data Exchange (ETDEWEB)

    Minamitsuji, M [ASC, LMU, Theresienst. 37, 80333 Munich (Germany)], E-mail: Masato.Minamitsuji@physik.uni-muenchen.de

    2008-04-25

    We discuss volume stabilization in a 6D braneworld model based on 6D supergravity theory. The internal space is compactified by magnetic flux and contains codimension two 3-branes (conical singularities) as its boundaries. In general the external 4D spacetime is warped and in the unwrapped limit the shape of the internal space looks like a 'rugby ball'. The size of the internal space is not fixed due to the scale invariance of the supergravity theory. We discuss the possibility of volume stabilization by the Casimir effect for a massless, minimally coupled bulk scalar field. The main obstacle in studying this case is that the brane (conical) part of the relevant heat kernel coefficient (a{sub 6}) has not been formulated. Thus as a first step, we consider the 4D analog model with boundary codimension two 1-branes. The spacetime structure of the 4D model is very similar to that of the original 6D model, where now the relevant heat kernel coefficient is well known. We derive the one-loop effective potential induced by a scalar field in the bulk by employing zeta function regularization with heat kernel analysis. As a result, the volume is stabilized for most possible choices of the parameters. Especially, for a larger degree of warping, our results imply that a large hierarchy between the mass scales and a tiny amount of effective cosmological constant can be realized on the brane. In the non-warped limit the ratio tends to converge to the same value, independently of the bulk gauge coupling constant. Finally, we will analyze volume stabilization in the original model 6D by employing the same mode-sum technique.

  12. On the Casimir scaling violation in the cusp anomalous dimension at small angle

    Science.gov (United States)

    Grozin, Andrey; Henn, Johannes; Stahlhofen, Maximilian

    2017-10-01

    We compute the four-loop n f contribution proportional to the quartic Casimir of the QCD cusp anomalous dimension as an expansion for small cusp angle ϕ. This piece is gauge invariant, violates Casimir scaling, and first appears at four loops. It requires the evaluation of genuine non-planar four-loop Feynman integrals. We present results up to O({φ}^4) . One motivation for our calculation is to probe a recent conjecture on the all-order structure of the cusp anomalous dimension. As a byproduct we obtain the four-loop HQET wave function anomalous dimension for this color structure.

  13. On the dynamical Casimir effect in 1 + 1 dimensions

    International Nuclear Information System (INIS)

    Alves, D.T.; Farina, C.; Maia Neto, P.A.; Tort, A.C.

    2000-01-01

    Full text follows: Vacuum field fluctuations exert radiation pressure on boundaries placed in empty space. If we take only one boundary at rest in vacuum, the total pressure exerted by the vacuum on the boundary is null. For two boundaries at rest in vacuum there is a net pressure exerted on the boundaries known as the Casimir effect. It has also been recognized that the dynamical counterparts of this static force appear for moving boundaries. In the dynamical case the existence of a net vacuum radiation pressure does not require the presence of two boundaries as in static case. Vacuum pressure already exists for a single boundary moving with a nonuniform acceleration. For that type of motion, the field does not remain in the vacuum state, but the quanta of the field are produced through nonadiabatic processes. In 1982 Ford and Vilenkin developed a perturbation method based on the static solution to calculate in first approximation the vacuum pressure exerted on a non-relativistic moving boundary. Using the method of Ford-Vilenkin we compute in the two dimensional quantum theory of a real massless scalar field the pressure exerted by the vacuum on a perfectly reflecting boundary moving with nonuniform acceleration around the coordinate x = 0 , having another boundary fixed at x = L. This simple model can provide insight into more sophisticated processes, such as photon production by moving mirrors and particle production in cosmological models and exploding black holes. (author)

  14. Poincare-Birkhoff-Witt theorems and generalized Casimir invariants for some infinite-dimensional Lie groups: II

    International Nuclear Information System (INIS)

    Ton-That, Tuong

    2005-01-01

    In a previous paper we gave a generalization of the notion of Casimir invariant differential operators for the infinite-dimensional Lie groups GL ∞ (C) (or equivalently, for its Lie algebra gj ∞ (C)). In this paper we give a generalization of the Casimir invariant differential operators for a class of infinite-dimensional Lie groups (or equivalently, for their Lie algebras) which contains the infinite-dimensional complex classical groups. These infinite-dimensional Lie groups, and their Lie algebras, are inductive limits of finite-dimensional Lie groups, and their Lie algebras, with some additional properties. These groups or their Lie algebras act via the generalized adjoint representations on projective limits of certain chains of vector spaces of universal enveloping algebras. Then the generalized Casimir operators are the invariants of the generalized adjoint representations. In order to be able to explicitly compute the Casimir operators one needs a basis for the universal enveloping algebra of a Lie algebra. The Poincare-Birkhoff-Witt (PBW) theorem gives an explicit construction of such a basis. Thus in the first part of this paper we give a generalization of the PBW theorem for inductive limits of Lie algebras. In the last part of this paper a generalization of the very important theorem in representation theory, namely the Chevalley-Racah theorem, is also discussed

  15. Repulsive Casimir and Casimir–Polder forces

    International Nuclear Information System (INIS)

    Milton, Kimball A; Abalo, E K; Parashar, Prachi; Pourtolami, Nima; Brevik, Iver; Ellingsen, Simen Å

    2012-01-01

    Casimir and Casimir–Polder repulsions have been known for more than 50 years. The general ‘Lifshitz’ configuration of parallel semi-infinite dielectric slabs permits repulsion if they are separated by a dielectric fluid that has a value of permittivity that is intermediate between those of the dielectric slabs. This was indirectly confirmed in the 1970s, and more directly by Capasso’s group recently. It has also been known for many years that electrically and magnetically polarizable bodies can experience a repulsive quantum vacuum force. More amenable to practical application are situations where repulsion could be achieved between ordinary conducting and dielectric bodies in vacuum. The status of the field of Casimir repulsion with emphasis on some recent developments will be surveyed. Here, stress will be placed on analytic developments, especially on Casimir–Polder (CP) interactions between anisotropically polarizable atoms, and CP interactions between anisotropic atoms and bodies that also exhibit anisotropy, either because of anisotropic constituents, or because of geometry. Repulsion occurs for wedge-shaped and cylindrical conductors, provided the geometry is sufficiently asymmetric, that is, either the wedge is sufficiently sharp or the atom is sufficiently far from the cylinder. This article is part of a special issue of Journal of Physics A: Mathematical and Theoretical in honour of Stuart Dowker’s 75th birthday devoted to ‘Applications of zeta functions and other spectral functions in mathematics and physics’. (review)

  16. Zeta-function approach to Casimir energy with singular potentials

    International Nuclear Information System (INIS)

    Khusnutdinov, Nail R.

    2006-01-01

    In the framework of zeta-function approach the Casimir energy for three simple model system: single delta potential, step function potential and three delta potentials are analyzed. It is shown that the energy contains contributions which are peculiar to the potentials. It is suggested to renormalize the energy using the condition that the energy of infinitely separated potentials is zero which corresponds to subtraction all terms of asymptotic expansion of zeta-function. The energy obtained in this way obeys all physically reasonable conditions. It is finite in the Dirichlet limit, and it may be attractive or repulsive depending on the strength of potential. The effective action is calculated, and it is shown that the surface contribution appears. The renormalization of the effective action is discussed

  17. Supersymmetry Breaking Casimir Warp Drive

    Science.gov (United States)

    Obousy, Richard K.; Cleaver, Gerald

    2007-01-01

    This paper utilizes a recent model which relates the cosmological constant to the Casimir energy of the extra dimensions in brane-world theories. The objective of this paper is to demonstrate that, given some sufficiently advanced civilization with the ability to manipulate the radius of the extra dimension, a local adjustment of the cosmological constant could be created. This adjustment would facilitate an expansion/contraction of the spacetime around a spacecraft creating an exotic form of field-propulsion. This idea is analogous to the Alcubierre bubble, but differs entirely in the approach, utilizing the physics of higher dimensional quantum field theory, instead of general relativity.

  18. Casimir-lifshitz force out of thermal equilibrium and asymptotic nonadditivity

    NARCIS (Netherlands)

    Antezza, Mauro; Pitaevskii, Lev P.; Stringari, Sandro; Svetovoy, Vitaly

    2006-01-01

    We investigate the force acting between two parallel plates held at different temperatures. The force reproduces, as limiting cases, the well-known Casimir-Lifshitz surface-surface force at thermal equilibrium and the surface-atom force out of thermal equilibrium recently derived by M. Antezza et

  19. Spatial dispersion in Casimir forces: a brief review

    Energy Technology Data Exchange (ETDEWEB)

    Esquivel-Sirvent, R [Instituto de FIsica, Universidad Nacional Autonoma de Mexico, Apartado Postal 20-364, 01000 Distrito Federal (Mexico); Villarreal, C [Instituto de FIsica, Universidad Nacional Autonoma de Mexico, Apartado Postal 20-364, 01000 Distrito Federal (Mexico); Mochan, W L [Centro de Ciencias FIsicas, Universidad Nacional Autonoma de Mexico, Apartado Postal 48-3, 62251 Cuernavaca, Morelos (Mexico); Contreras-Reyes, A M [Department of Physics and Astronomy, University of Sussex, Brighton, East Sussex BN1 9QH (United Kingdom); Svetovoy, V B [MESA Research Institute, University of Twente, PO Box 217, 7500 AE Enschede (Netherlands)

    2006-05-26

    We present the basic principles of non-local optics in connection with the calculation of the Casimir force between half-spaces and thin films. At currently accessible distances L, non-local corrections amount to about half a per cent, but they increase roughly as 1/L at smaller separations. Self-consistent models lead to corrections with the opposite sign as models with abrupt surfaces.

  20. Casimir Repulsion between Metallic Objects in Vacuum

    International Nuclear Information System (INIS)

    Levin, Michael; McCauley, Alexander P.; Rodriguez, Alejandro W.; Reid, M. T. Homer; Johnson, Steven G.

    2010-01-01

    We give an example of a geometry in which two metallic objects in vacuum experience a repulsive Casimir force. The geometry consists of an elongated metal particle centered above a metal plate with a hole. We prove that this geometry has a repulsive regime using a symmetry argument and confirm it with numerical calculations for both perfect and realistic metals. The system does not support stable levitation, as the particle is unstable to displacements away from the symmetry axis.

  1. Spherical Casimir pistons

    Energy Technology Data Exchange (ETDEWEB)

    Dowker, J S, E-mail: dowker@man.ac.uk [Theory Group, School of Physics and Astronomy, University of Manchester, Manchester (United Kingdom)

    2011-08-07

    A piston is introduced into a spherical lune Casimir cavity turning it into two adjacent lunes separated by the (hemispherical) piston. On the basis of zeta-function regularization, the vacuum energy of the arrangement is finite for conformal propagation in spacetime. For even spheres this energy is independent of the angle of the lune. For odd dimensions it is shown that for all Neumann, or all Dirichlet, boundary conditions the piston is repelled or attracted by the nearest wall if d = 3, 7, ... or if d = 1, 5, ... , respectively. For hybrid N-D conditions these requirements are switched. If a mass is added, divergences arise which render the model suspect. The analysis, however, is relatively straightforward and involves the Barnes zeta function. The extension to finite temperatures is made and it is shown that for the 3, 7, ... series of odd spheres, the repulsion by the walls continues but that, above a certain temperature, the free energy acquires two minima symmetrically placed about the midpoint.

  2. Spherical Casimir pistons

    International Nuclear Information System (INIS)

    Dowker, J S

    2011-01-01

    A piston is introduced into a spherical lune Casimir cavity turning it into two adjacent lunes separated by the (hemispherical) piston. On the basis of zeta-function regularization, the vacuum energy of the arrangement is finite for conformal propagation in spacetime. For even spheres this energy is independent of the angle of the lune. For odd dimensions it is shown that for all Neumann, or all Dirichlet, boundary conditions the piston is repelled or attracted by the nearest wall if d = 3, 7, ... or if d = 1, 5, ... , respectively. For hybrid N-D conditions these requirements are switched. If a mass is added, divergences arise which render the model suspect. The analysis, however, is relatively straightforward and involves the Barnes zeta function. The extension to finite temperatures is made and it is shown that for the 3, 7, ... series of odd spheres, the repulsion by the walls continues but that, above a certain temperature, the free energy acquires two minima symmetrically placed about the midpoint.

  3. Energy shift and Casimir-Polder force for an atom out of thermal equilibrium near a dielectric substrate

    Science.gov (United States)

    Zhou, Wenting; Yu, Hongwei

    2014-09-01

    We study the energy shift and the Casimir-Polder force of an atom out of thermal equilibrium near the surface of a dielectric substrate. We first generalize, adopting the local source hypothesis, the formalism proposed by Dalibard, Dupont-Roc, and Cohen-Tannoudji [J. Phys. (Paris) 43, 1617 (1982), 10.1051/jphys:0198200430110161700; J. Phys. (Paris) 45, 637 (1984), 10.1051/jphys:01984004504063700], which separates the contributions of thermal fluctuations and radiation reaction to the energy shift and allows a distinct treatment of atoms in the ground and excited states, to the case out of thermal equilibrium, and then we use the generalized formalism to calculate the energy shift and the Casimir-Polder force of an isotropically polarizable neutral atom. We identify the effects of the thermal fluctuations that originate from the substrate and the environment and discuss in detail how the Casimir-Polder force out of thermal equilibrium behaves in three different distance regions in both the low-temperature limit and the high-temperature limit for both the ground-state and excited-state atoms, with special attention devoted to the distinctive features as opposed to thermal equilibrium. In particular, we recover the distinctive behavior of the atom-wall force out of thermal equilibrium at large distances in the low-temperature limit recently found in a different theoretical framework, and furthermore we give a concrete region where this behavior holds.

  4. Nonlinear dynamics of a rack-pinion-rack device powered by the Casimir force.

    Science.gov (United States)

    Miri, MirFaez; Nekouie, Vahid; Golestanian, Ramin

    2010-01-01

    Using the lateral Casimir force-a manifestation of the quantum fluctuations of the electromagnetic field between objects with corrugated surfaces-as the main force transduction mechanism, a nanomechanical device with rich dynamical behaviors is proposed. The device is made of two parallel racks that are moving in the same direction and a pinion in the middle that couples with both racks via the noncontact lateral Casimir force. The built-in frustration in the device causes it to be very sensitive and react dramatically to minute changes in the geometrical parameters and initial conditions of the system. The noncontact nature of the proposed device could help with the ubiquitous wear problem in nanoscale mechanical systems.

  5. Geometry and spectrum of Casimir forces

    International Nuclear Information System (INIS)

    Buescher, Rauno; Emig, Thorsten

    2005-01-01

    We present a new approach to the Helmholtz spectrum for arbitrarily shaped boundaries and general boundary conditions. We derive the boundary induced change of the density of states in terms of the free Green's function from which we obtain nonperturbative results for the Casimir interaction between rigid surfaces. As an example, we compute the lateral electrodynamic force between two corrugated surfaces over a wide parameter range. Universal behavior, fixed only by the largest wavelength component of the surface shape, is identified at large surface separations, complementing known short distance expansions which we also reproduce with high precision

  6. BPS ZN string tensions, sine law and Casimir scaling, and integrable field theories

    International Nuclear Information System (INIS)

    Kneipp, Marco A. C.

    2007-01-01

    We consider a Yang-Mills-Higgs theory with spontaneous symmetry breaking of the gauge group G→U(1) r →C G , with C G being the center of G. We study two vacua solutions of the theory which produce this symmetry breaking. We show that for one of these vacua, the theory in the Coulomb phase has the mass spectrum of particles and monopoles which is exactly the same as the mass spectrum of particles and solitons of two-dimensional affine Toda field theory, for suitable coupling constants. That result holds also for N=4 super Yang-Mills theories. On the other hand, in the Higgs phase, we show that for each of the two vacua the ratio of the tensions of the BPS Z N strings satisfy either the Casimir scaling or the sine law scaling for G=SU(N). These results are extended to other gauge groups: for the Casimir scaling, the ratios of the tensions are equal to the ratios of the quadratic Casimir constant of specific representations; for the sine law scaling, the tensions are proportional to the components of the left Perron-Frobenius eigenvector of Cartan matrix K ij and the ratios of tensions are equal to the ratios of the soliton masses of affine Toda field theories

  7. Helical bifurcation and tearing mode in a plasma—a description based on Casimir foliation

    International Nuclear Information System (INIS)

    Yoshida, Z; Dewar, R L

    2012-01-01

    The relation between the helical bifurcation of a Taylor relaxed state (a Beltrami equilibrium) and a tearing mode is analyzed in a Hamiltonian framework. Invoking an Eulerian representation of the Hamiltonian, the symplectic operator (defining a Poisson bracket) becomes non-canonical, i.e. the symplectic operator has a nontrivial cokernel (dual to its nullspace), foliating the phase space into level sets of Casimir invariants. A Taylor relaxed state is an equilibrium point on a Casimir (helicity) leaf. Changing the helicity, equilibrium points may bifurcate to produce helical relaxed states; a necessary and sufficient condition for bifurcation is derived. Tearing yields a helical perturbation on an unstable equilibrium, producing a helical structure approximately similar to a helical relaxed state. A slight discrepancy found between the helically bifurcated relaxed state and the linear tearing mode viewed as a perturbed, singular equilibrium state is attributed to a Casimir element (named ‘helical flux’) pertinent to a ‘resonance singularity’ of the non-canonical symplectic operator. While the helical bifurcation can occur at discrete eigenvalues of the Beltrami parameter, the tearing mode, being a singular eigenfunction, exists for an arbitrary Beltrami parameter. Bifurcated Beltrami equilibria appearing on the same helicity leaf are isolated by the helical-flux Casimir foliation. The obstacle preventing the tearing mode to develop in the ideal limit turns out to be the shielding current sheet on the resonant surface, preventing the release of the ‘potential energy’. When this current is dissipated by resistivity, reconnection is allowed and tearing instability occurs. The Δ′ criterion for linear tearing instability of Beltrami equilibria is shown to be directly related to the spectrum of the curl operator. (paper)

  8. Attractive electromagnetic Casimir stress on a spherical dielectric shell

    International Nuclear Information System (INIS)

    Graham, N.; Quandt, M.; Weigel, H.

    2013-01-01

    Based on calculations involving an idealized boundary condition, it has long been assumed that the stress on a spherical conducting shell is repulsive. We use the more realistic case of a Drude dielectric to show that the stress is attractive, matching the generic behavior of Casimir forces in electromagnetism. We trace the discrepancy between these two cases to interactions between the electromagnetic quantum fluctuations and the dielectric material

  9. Quantum mechanical effects of topological origin

    Science.gov (United States)

    Duru, I. H.

    1993-01-01

    Following a brief review of the original Casimir and Aharonov-Bohm effects, some other effects of similar natures are mentioned. A Casimir interaction between AB fluxes is presented. Possible realizations of the Casimir effects for massive charged fields in solid state structures and a new AB effect for photons are suggested.

  10. Generalized Riemann zeta-function regularization and Casimir energy for a piecewise uniform string

    International Nuclear Information System (INIS)

    Li Xinzhou; Shi Xin; Zhang Jianzu.

    1990-12-01

    The generalized zeta-function techniques will be utilized to investigate the Casimir energy for the transverse oscillations of a piecewise uniform closed string. We find that zeta-function regularization method can lead straightforwardly to a correct result. (author). 6 refs

  11. Casimir energy in d-dimensional rectangular geometries, under mixed boundary conditions

    International Nuclear Information System (INIS)

    Silva, J.C. da; Placido, Hebe Q.; Santana, A.E.; M Neto, Arthur

    1997-01-01

    The Casimir energy and its temperature corrections are presented for the electromagnetic field confined in a d-dimensional hypercavity. The expressions are derived considering Dirichlet boundary conditions for each pair of hyperplanes defining a confined direction (the homogeneous case); or yet, by choosing different boundary conditions (Dirichlet or Neumann) at each hyperplane of the pair (the mixed case). (author)

  12. Oscillating dipole layer facing a conducting plane: a classical analogue of the dynamical Casimir effect

    Energy Technology Data Exchange (ETDEWEB)

    Fosco, César D. [Centro Atómico Bariloche, Instituto Balseiro, Comisión Nacional de Energía Atómica, R8402AGP, Bariloche (Argentina); Lombardo, Fernando C., E-mail: lombardo@df.uba.ar [Departamento de Física Juan José Giambiagi, FCEyN UBA and IFIBA CONICET-UBA, Facultad de Ciencias Exactas y Naturales, Ciudad Universitaria, Pabellón I, 1428, Buenos Aires (Argentina)

    2015-12-17

    We study the properties of the classical electromagnetic radiation produced by two physically different yet closely related systems, which may be regarded as classical analogues of the dynamical Casimir effect. They correspond to two flat, infinite, parallel planes, one of them static and imposing perfect-conductor boundary conditions, while the other performs a rigid oscillatory motion. The systems differ just in the electrical properties of the oscillating plane: one of them is just a planar dipole layer (representing, for instance, a small-width electret). The other, instead, has a dipole layer on the side which faces the static plane, but behaves as a conductor on the other side: this can be used as a representation of a conductor endowed with patch potentials (on the side which faces the conducting plane). We evaluate, in both cases, the dissipative flux of energy between the system and its environment, showing that, at least for small mechanical oscillation amplitudes, it can be written in terms of the dipole layer autocorrelation function. We show that there are resonances as a function of the frequency of the mechanical oscillation.

  13. Casimir energy of massless fermions in the Slab-bag

    International Nuclear Information System (INIS)

    Paola, R.D.M. de; Rodrigues, R.B.; Svaiter, N.F.

    1999-04-01

    The zero-point energy of a massless fermion field in the interior of two parallel plates in a D-dimensional space-time at zero temperature is calculated. In order to regularize the model, a mix between dimensional and zeta function regularization procedure is used and it is founded that the regularized zero-point energy density is finite for any number of space-time dimensions. We present a general expression for the Casimir energy for the fermionic field in such a situation. (author)

  14. Modifying the Casimir force between indium tin oxide film and Au sphere

    Science.gov (United States)

    Banishev, A. A.; Chang, C.-C.; Castillo-Garza, R.; Klimchitskaya, G. L.; Mostepanenko, V. M.; Mohideen, U.

    2012-01-01

    We present complete results of the experiment on measuring the Casimir force between an Au-coated sphere and an untreated or, alternatively, UV-treated indium tin oxide (ITO) film deposited on a quartz substrate. Measurements were performed using an atomic force microscope in a high vacuum chamber. The measurement system was calibrated electrostatically. Special analysis of the systematic deviations is performed, and respective corrections in the calibration parameters are introduced. The corrected parameters are free from anomalies discussed in the literature. The experimental data for the Casimir force from two measurement sets for both untreated and UV-treated samples are presented. The random, systematic, and total experimental errors are determined at a 95% confidence level. It is demonstrated that the UV treatment of an ITO plate results in a significant decrease in the magnitude of the Casimir force (from 21% to 35% depending on separation). However, ellipsometry measurements of the imaginary parts of dielectric permittivities of the untreated and UV-treated samples did not reveal any significant differences. The experimental data are compared with computations in the framework of the Lifshitz theory. It is found that the data for the untreated sample are in a very good agreement with theoretical results taking into account the free charge carriers in an ITO film. For the UV-treated sample the data exclude the theoretical results obtained with account of free charge carriers. These data are in very good agreement with computations disregarding the contribution of free carriers in the dielectric permittivity. According to the hypothetical explanation provided, this is caused by the phase transition of the ITO film from metallic to dielectric state caused by the UV treatment. Possible applications of the discovered phenomenon in nanotechnology are discussed.

  15. Determination of the Contact Angle Based on the Casimir Effect

    Science.gov (United States)

    Mazuruk, Konstantin; Volz, Martin P.

    2015-01-01

    On a macroscopic scale, a nonreactive liquid partially covering a homogeneous solid surface will intersect the solid at an angle called the contact angle. For molten metals and semiconductors, the contact angle is materially dependent upon both the solid and liquid and typical values fall in the range 80-170 deg, depending on the crucible material. On a microscopic scale, there does not exist a precise and sharp contact angle but rather the liquid and solid surfaces merge smoothly and continuously. Consider the example of the so called detached Bridgman crystal growth process. In this technique, a small gap is formed between the growing crystal and the crucible. At the crystal/melt interface, a meniscus ring is formed. Its width can be in the range of a few micrometers, approaching a microscopic scale. It then becomes questionable to describe the shape of this meniscus by the contact angle. A more advanced treatment of the interface is needed and here we propose such a refined model. The interaction of the liquid surface with the solid can be calculated by considering two forces: a short-range repulsive force and a longer range (up to a few micrometers) Casimir or van der Waals force.

  16. Virtual photons in imaginary time: Computing exact Casimir forces via standard numerical electromagnetism techniques

    NARCIS (Netherlands)

    Rodriguez, A.; Ibanescu, M.; Iannuzzi, D.; Joannopoulos, J. D.; Johnson, S.T.

    2007-01-01

    We describe a numerical method to compute Casimir forces in arbitrary geometries, for arbitrary dielectric and metallic materials, with arbitrary accuracy (given sufficient computational resources). Our approach, based on well-established integration of the mean stress tensor evaluated via the

  17. Representations of the exceptional and other Lie algebras with integral eigenvalues of the Casimir operator

    International Nuclear Information System (INIS)

    Macfarlane, A J; Pfeiffer, Hendryk

    2003-01-01

    The uniformity, for the family of exceptional Lie algebras g, of the decompositions of the powers of their adjoint representations is now well known for powers up to four. The paper describes an extension of this uniformity for the totally antisymmetrized nth powers up to n = 9, identifying families of representations with integer eigenvalues 5, ..., 9 for the quadratic Casimir operator, in each case providing a formula for the dimensions of the representations in the family as a function of D = dim g. This generalizes previous results for powers j and Casimir eigenvalues j, j ≤ 4. Many intriguing, perhaps puzzling, features of the dimension formulae are discussed and the possibility that they may be valid for a wider class of not necessarily simple Lie algebras is considered

  18. Casimir energy and a cosmological bounce

    International Nuclear Information System (INIS)

    Herdeiro, Carlos A R; Sampaio, Marco

    2006-01-01

    We review different computation methods for the renormalized energy-momentum tensor of a quantized scalar field in an Einstein static universe. For the extensively studied conformally coupled case, we check their equivalence; for different couplings, we discuss violation of different energy conditions. In particular, there is a family of masses and couplings which violate the weak and strong energy conditions but do not lead to spacelike propagation. Amongst these cases is that of a minimally coupled massless scalar field with no potential. We also point out a particular coupling for which a massless scalar field has vanishing renormalized energy-momentum tensor. We discuss the backreaction problem and in particular the possibility that this Casimir energy could both source a short inflationary epoch and avoid the big bang singularity through a bounce

  19. Casimir effect of two conducting parallel plates in a general weak gravitational field

    Energy Technology Data Exchange (ETDEWEB)

    Nazari, Borzoo [University of Tehran, Faculty of Engineering Science, College of Engineering, P.O. Box 11155-4563, Tehran (Iran, Islamic Republic of)

    2015-10-15

    We calculate the finite vacuum energy density of the scalar and electromagnetic fields inside a Casimir apparatus made up of two conducting parallel plates in a general weak gravitational field. The metric of the weak gravitational field has a small deviation from flat spacetime inside the apparatus, and we find it by expanding the metric in terms of small parameters of the weak background. We show that the metric found can be transformed via a gauge transformation to the Fermi metric. We solve the Klein-Gordon equation exactly and find mode frequencies in Fermi spacetime. Using the fact that the electromagnetic field can be represented by two scalar fields in the Fermi spacetime, we find general formulas for the energy density and mode frequencies of the electromagnetic field. Some well-known weak backgrounds are examined and consistency of the results with the literature is shown. (orig.)

  20. Stability and the proximity theorem in Casimir actuated nano devices

    Science.gov (United States)

    Esquivel-Sirvent, R.; Reyes, L.; Bárcenas, J.

    2006-10-01

    A brief description of the stability problem in micro and nano electromechanical devices (MEMS/NEMS) actuated by Casimir forces is given. To enhance the stability, we propose the use of curved surfaces and recalculate the stability conditions by means of the proximity force approximation. The use of curved surfaces changes the bifurcation point, and the radius of curvature becomes a control parameter, allowing a rescaling of the elastic restitution constant and/or of the typical dimensions of the device.

  1. Dynamic Pull-In Investigation of a Clamped-Clamped Nanoelectromechanical Beam under Ramp-Input Voltage and the Casimir Force

    Directory of Open Access Journals (Sweden)

    Amir R. Askari

    2014-01-01

    Full Text Available The influence of the Casimir excitation on dynamic pull-in instability of a nanoelectromechanical beam under ramp-input voltage is studied. The ramp-input actuation has applications in frequency sweeping of RF-N/MEMS. The presented model is nonlinear due to the inherent nonlinearity of electrostatics and the Casimir excitations as well as the geometric nonlinearity of midplane stretching. A Galerkin based reduced order modeling is utilized. It is found that the calculated dynamic pull-in ramp input voltage leads to dynamic pull-in step input voltage by increasing the slope of voltage-time diagram. This fact is utilized to verify the results of present study.

  2. Reply to 'Comment on 'Surface-impedance approach solves problems with the thermal Casimir force between real metals''

    International Nuclear Information System (INIS)

    Geyer, B.; Klimchitskaya, G.L.; Mostepanenko, V.M.

    2004-01-01

    The preceding Comment discusses in detail the main idea of our paper [Phys. Rev. A 67, 062102 (2003)], namely that one cannot substitute the Drude dielectric function into the Lifshitz formula for the thermal Casimir force in the frequency region where a real current of conduction electrons leads to Joule heating in the metal. In that Comment, it is claimed that this idea would be in contradiction to the fluctuation-dissipation theorem. In this Reply we present an explicit explanation why there is no contradiction. In the second part of the Comment an alternative method is suggested, different from the one used in our paper, to calculate the thermal Casimir force in the framework of the impedance approach. This method is in support of a previous prediction by Svetovoy and Lokhanin, criticized by us, that there exists a relatively large thermal correction to the Casimir force between real metals at small separations. Here we present strong quantitative arguments in favor of the statement that the method of the Comment is in violation of the Nernst heat theorem. We also demonstrate that it is in contradiction with experiment. The approach of our paper is shown to be in agreement with both thermodynamics and experimental data

  3. Finite temperature Casimir energy in closed rectangular cavities: a rigorous derivation based on a zeta function technique

    International Nuclear Information System (INIS)

    Lim, S C; Teo, L P

    2007-01-01

    We derive rigorously explicit formulae of the Casimir free energy at finite temperature for massless scalar field and electromagnetic field confined in a closed rectangular cavity with different boundary conditions by a zeta regularization method. We study both the low and high temperature expansions of the free energy. In each case, we write the free energy as a sum of a polynomial in temperature plus exponentially decay terms. We show that the free energy is always a decreasing function of temperature. In the cases of massless scalar field with the Dirichlet boundary condition and electromagnetic field, the zero temperature Casimir free energy might be positive. In each of these cases, there is a unique transition temperature (as a function of the side lengths of the cavity) where the Casimir energy changes from positive to negative. When the space dimension is equal to two and three, we show graphically the dependence of this transition temperature on the side lengths of the cavity. Finally we also show that we can obtain the results for a non-closed rectangular cavity by letting the size of some directions of a closed cavity go to infinity, and we find that these results agree with the usual integration prescription adopted by other authors

  4. Oscillating dipole layer facing a conducting plane: a classical analogue of the dynamical Casimir effect

    Energy Technology Data Exchange (ETDEWEB)

    Fosco, Cesar D. [Comision Nacional de Energia Atomica, Centro Atomico Bariloche, Instituto Balseiro, Bariloche (Argentina); Lombardo, Fernando C. [Ciudad Universitaria, Departamento de Fisica Juan Jose Giambiagi, FCEyN UBA y IFIBA CONICET-UBA, Facultad de Ciencias Exactas y Naturales, Buenos Aires (Argentina)

    2015-12-15

    We study the properties of the classical electromagnetic radiation produced by two physically different yet closely related systems, which may be regarded as classical analogues of the dynamical Casimir effect. They correspond to two flat, infinite, parallel planes, one of them static and imposing perfect-conductor boundary conditions, while the other performs a rigid oscillatory motion. The systems differ just in the electrical properties of the oscillating plane: one of them is just a planar dipole layer (representing, for instance, a small-width electret). The other, instead, has a dipole layer on the side which faces the static plane, but behaves as a conductor on the other side: this can be used as a representation of a conductor endowed with patch potentials (on the side which faces the conducting plane). We evaluate, in both cases, the dissipative flux of energy between the system and its environment, showing that, at least for small mechanical oscillation amplitudes, it can be written in terms of the dipole layer autocorrelation function. We show that there are resonances as a function of the frequency of the mechanical oscillation. (orig.)

  5. Oscillating dipole layer facing a conducting plane: a classical analogue of the dynamical Casimir effect

    International Nuclear Information System (INIS)

    Fosco, Cesar D.; Lombardo, Fernando C.

    2015-01-01

    We study the properties of the classical electromagnetic radiation produced by two physically different yet closely related systems, which may be regarded as classical analogues of the dynamical Casimir effect. They correspond to two flat, infinite, parallel planes, one of them static and imposing perfect-conductor boundary conditions, while the other performs a rigid oscillatory motion. The systems differ just in the electrical properties of the oscillating plane: one of them is just a planar dipole layer (representing, for instance, a small-width electret). The other, instead, has a dipole layer on the side which faces the static plane, but behaves as a conductor on the other side: this can be used as a representation of a conductor endowed with patch potentials (on the side which faces the conducting plane). We evaluate, in both cases, the dissipative flux of energy between the system and its environment, showing that, at least for small mechanical oscillation amplitudes, it can be written in terms of the dipole layer autocorrelation function. We show that there are resonances as a function of the frequency of the mechanical oscillation. (orig.)

  6. Casimir rack and pinion as a miniaturized kinetic energy harvester

    Science.gov (United States)

    Miri, MirFaez; Etesami, Zahra

    2016-08-01

    We study a nanoscale machine composed of a rack and a pinion with no contact, but intermeshed via the lateral Casimir force. We adopt a simple model for the random velocity of the rack subject to external random forces, namely, a dichotomous noise with zero mean value. We show that the pinion, even when it experiences random thermal torque, can do work against a load. The device thus converts the kinetic energy of the random motions of the rack into useful work.

  7. Calculation of nonzero-temperature Casimir forces in the time domain

    International Nuclear Information System (INIS)

    Pan, Kai; Reid, M. T. Homer; McCauley, Alexander P.; Rodriguez, Alejandro W.; White, Jacob K.; Johnson, Steven G.

    2011-01-01

    We show how to compute Casimir forces at nonzero temperatures with time-domain electromagnetic simulations, for example, using a finite-difference time-domain (FDTD) method. Compared to our previous zero-temperature time-domain method, only a small modification is required, but we explain that some care is required to properly capture the zero-frequency contribution. We validate the method against analytical and numerical frequency-domain calculations, and show a surprising high-temperature disappearance of a nonmonotonic behavior previously demonstrated in a pistonlike geometry.

  8. On electrostatic and Casimir force measurements between conducting surfaces in a sphere-plane configuration

    International Nuclear Information System (INIS)

    Kim, W J; Brown-Hayes, M; Brownell, J H; Dalvit, D A R; Onofrio, R

    2009-01-01

    We report on measurements of forces acting between two conducting surfaces in a spherical-plane configuration in the 35 nm-1 μm separation range. The measurements are obtained by performing electrostatic calibrations followed by a residuals analysis after subtracting the electrostatic-dependent component. We find in all runs optimal fitting of the calibrations for exponents smaller than the one predicted by electrostatics for an ideal sphere-plane geometry. We also find that the external bias potential necessary to minimize the electrostatic contribution depends on the sphere-plane distance. In spite of these anomalies, by implementing a parametrization-dependent subtraction of the electrostatic contribution we have found evidence for short-distance attractive forces of magnitude comparable to the expected Casimir-Lifshitz force. We finally discuss the relevance of our findings in the more general context of Casimir-Lifshitz force measurements, with particular regard to the critical issues of the electrical and geometrical characterization of the involved surfaces.

  9. Virtual photons in imaginary time: Computing exact Casimir forces via standard numerical electromagnetism techniques

    International Nuclear Information System (INIS)

    Rodriguez, Alejandro; Ibanescu, Mihai; Joannopoulos, J. D.; Johnson, Steven G.; Iannuzzi, Davide

    2007-01-01

    We describe a numerical method to compute Casimir forces in arbitrary geometries, for arbitrary dielectric and metallic materials, with arbitrary accuracy (given sufficient computational resources). Our approach, based on well-established integration of the mean stress tensor evaluated via the fluctuation-dissipation theorem, is designed to directly exploit fast methods developed for classical computational electromagnetism, since it only involves repeated evaluation of the Green's function for imaginary frequencies (equivalently, real frequencies in imaginary time). We develop the approach by systematically examining various formulations of Casimir forces from the previous decades and evaluating them according to their suitability for numerical computation. We illustrate our approach with a simple finite-difference frequency-domain implementation, test it for known geometries such as a cylinder and a plate, and apply it to new geometries. In particular, we show that a pistonlike geometry of two squares sliding between metal walls, in both two and three dimensions with both perfect and realistic metallic materials, exhibits a surprising nonmonotonic ''lateral'' force from the walls

  10. Lateral Casimir-Polder forces by breaking time-reversal symmetry

    Science.gov (United States)

    Oude Weernink, Ricardo R. Q. P. T.; Barcellona, Pablo; Buhmann, Stefan Yoshi

    2018-03-01

    We examine the lateral Casimir-Polder force acting on a circular rotating emitter near a dielectric plane surface. As the circular motion breaks time-reversal symmetry, the spontaneous emission in a direction parallel to the surface is in general anisotropic. We show that a lateral force arises which can be interpreted as a recoil force because of this asymmetric emission. The force is an oscillating function of the distance between the emitter and the surface, and the lossy character of the dielectric strongly influences the results in the near-field regime. The force exhibits also a population-induced dynamics, decaying exponentially with respect to time on time scales of the inverse of the spontaneous decay rate. We propose that this effect could be detected measuring the velocity acquired by the emitter, following different cycles of excitation and spontaneous decay. Our results are expressed in terms of the Green's tensor and can therefore easily be applied to more complex geometries.

  11. Casimir amplitudes and capillary condensation of near-critical fluids between parallel plates: renormalized local functional theory.

    Science.gov (United States)

    Okamoto, Ryuichi; Onuki, Akira

    2012-03-21

    We investigate the critical behavior of a near-critical fluid confined between two parallel plates in contact with a reservoir by calculating the order parameter profile and the Casimir amplitudes (for the force density and for the grand potential). Our results are applicable to one-component fluids and binary mixtures. We assume that the walls absorb one of the fluid components selectively for binary mixtures. We propose a renormalized local functional theory accounting for the fluctuation effects. Analysis is performed in the plane of the temperature T and the order parameter in the reservoir ψ(∞). Our theory is universal if the physical quantities are scaled appropriately. If the component favored by the walls is slightly poor in the reservoir, there appears a line of first-order phase transition of capillary condensation outside the bulk coexistence curve. The excess adsorption changes discontinuously between condensed and noncondensed states at the transition. With increasing T, the transition line ends at a capillary critical point T=T(c) (ca) slightly lower than the bulk critical temperature T(c) for the upper critical solution temperature. The Casimir amplitudes are larger than their critical point values by 10-100 times at off-critical compositions near the capillary condensation line. © 2012 American Institute of Physics

  12. Casimir quantum levitation tuned by means of material properties and geometries

    OpenAIRE

    Dou, Maofeng; Lui, F; Boström, Mathias; Brevik, Iver Håkon; Persson, Clas

    2014-01-01

    The Casimir force between two surfaces is attractive in most cases. Although stable suspension of nano-objects has been achieved, the sophisticated geometries make them difficult to be merged with well-established thin film processes. We find that by introducing thin film surface coating on porous substrates, a repulsive to attractive force transition is achieved when the separations are increased in planar geometries, resulting in a stable suspension of two surfaces near the force transition...

  13. Coupled-oscillator theory of dispersion and Casimir-Polder interactions

    Energy Technology Data Exchange (ETDEWEB)

    Berman, P. R.; Ford, G. W. [Physics Department, University of Michigan, 450 Church Street, Ann Arbor, Michigan 48109-1040 (United States); Milonni, P. W. [Theoretical Division, Los Alamos National Laboratory, Los Alamos, New Mexico 87545 (United States); Department of Physics and Astronomy, University of Rochester, Rochester, New York 14627 (United States)

    2014-10-28

    We address the question of the applicability of the argument theorem (of complex variable theory) to the calculation of two distinct energies: (i) the first-order dispersion interaction energy of two separated oscillators, when one of the oscillators is excited initially and (ii) the Casimir-Polder interaction of a ground-state quantum oscillator near a perfectly conducting plane. We show that the argument theorem can be used to obtain the generally accepted equation for the first-order dispersion interaction energy, which is oscillatory and varies as the inverse power of the separation r of the oscillators for separations much greater than an optical wavelength. However, for such separations, the interaction energy cannot be transformed into an integral over the positive imaginary axis. If the argument theorem is used incorrectly to relate the interaction energy to an integral over the positive imaginary axis, the interaction energy is non-oscillatory and varies as r{sup −4}, a result found by several authors. Rather remarkably, this incorrect expression for the dispersion energy actually corresponds to the nonperturbative Casimir-Polder energy for a ground-state quantum oscillator near a perfectly conducting wall, as we show using the so-called “remarkable formula” for the free energy of an oscillator coupled to a heat bath [G. W. Ford, J. T. Lewis, and R. F. O’Connell, Phys. Rev. Lett. 55, 2273 (1985)]. A derivation of that formula from basic results of statistical mechanics and the independent oscillator model of a heat bath is presented.

  14. Coupled-oscillator theory of dispersion and Casimir-Polder interactions

    International Nuclear Information System (INIS)

    Berman, P. R.; Ford, G. W.; Milonni, P. W.

    2014-01-01

    We address the question of the applicability of the argument theorem (of complex variable theory) to the calculation of two distinct energies: (i) the first-order dispersion interaction energy of two separated oscillators, when one of the oscillators is excited initially and (ii) the Casimir-Polder interaction of a ground-state quantum oscillator near a perfectly conducting plane. We show that the argument theorem can be used to obtain the generally accepted equation for the first-order dispersion interaction energy, which is oscillatory and varies as the inverse power of the separation r of the oscillators for separations much greater than an optical wavelength. However, for such separations, the interaction energy cannot be transformed into an integral over the positive imaginary axis. If the argument theorem is used incorrectly to relate the interaction energy to an integral over the positive imaginary axis, the interaction energy is non-oscillatory and varies as r −4 , a result found by several authors. Rather remarkably, this incorrect expression for the dispersion energy actually corresponds to the nonperturbative Casimir-Polder energy for a ground-state quantum oscillator near a perfectly conducting wall, as we show using the so-called “remarkable formula” for the free energy of an oscillator coupled to a heat bath [G. W. Ford, J. T. Lewis, and R. F. O’Connell, Phys. Rev. Lett. 55, 2273 (1985)]. A derivation of that formula from basic results of statistical mechanics and the independent oscillator model of a heat bath is presented

  15. On the effects from the simultaneous occurrence of the critical Casimir and dispersion forces between conical colloid particle and a thick plate immersed in nonpolar critical fluid

    Directory of Open Access Journals (Sweden)

    Valchev Galin

    2018-01-01

    Full Text Available Here we study the interplay between the van der Waals (vdWF and critical Casimir forces (CCF, as well as the total force (TF between a conical colloid particle and a thick planar slab. We do that using general scaling arguments and mean-field type calculations utilizing the so-called “surface integration approach”, a generalization of the well known Derjaguin approximation. Its usage in the present research, requires knowledge on the forces between two parallel slabs, confining in between some fluctuating fluid medium characterized by its temperature T and chemical potential μ. The surfaces of the colloid particle and the slab are assumed coated by thin layers exerting strong preference to the liquid phase of a simple fluid, or one of the components of a binary mixture, modeled by strong adsorbing local surface potentials, ensuring the so-called (+,+ boundary conditions. On the other hand, the core region of the slab and the particle, influence the fluid by long-ranged competing dispersion potentials. We demonstrate that for a suitable set of colloid-fluid, slab-fluid, and fluid-fluid coupling parameters the competition between the effects due to the coatings and the core regions of the objects, result, when one changes T or μ, in sign change of the Casimir force (CF and the TF acting between the colloid and the slab. Such an effect can provide a strategy for solving problems with handling, feeding, trapping and fixing of microparts in nanotechnology.

  16. Casimir Force Between Quantum Plasmas

    International Nuclear Information System (INIS)

    Buenzli, P.

    2005-01-01

    Field fluctuations are responsible for an attractive force - the Casimir force - between two parallel (globally neutral) metallic plates separated by a distance d. At high temperature, or equivalently large d, this force is known to exhibit a classical and universal character (independent of the material constitution of the plates). In a recent work, we have displayed the microscopic mechanisms responsible for this universality within a classical model. The plates consist of slabs containing classical charged particles in fluid phase and thermal equilibrium (plasmas). The universality of the force proves to originate from screening sum rules satisfied by the charge correlations. Here we show how this result is altered when the quantum-mechanical nature of the particles is taken into account. It turns out that in addition to the classical result, the asymptotic force for large d comprises a non-universal quantum correction, which is, however, small at high temperature. The method relies on an exact representation of the charge correlations by quantum Mayer graphs, based on the Feynman-Kac path integral formalism. (author)

  17. Local and global Casimir energies for a semitransparent cylindrical shell

    International Nuclear Information System (INIS)

    Cavero-Pelaez, Ines; Milton, Kimball A; Kirsten, Klaus

    2007-01-01

    The local Casimir energy density and the global Casimir energy for a massless scalar field associated with a λδ-function potential in a (3 + 1)-dimensional circular cylindrical geometry are considered. The global energy is examined for both weak and strong coupling, the latter being the well-studied Dirichlet cylinder case. For weak coupling, through O(λ 2 ), the total energy is shown to vanish by both analytic and numerical arguments, based both on Green's-function and zeta-function techniques. Divergences occurring in the calculation are shown to be absorbable by renormalization of physical parameters of the model. The global energy may be obtained by integrating the local energy density only when the latter is supplemented by an energy term residing precisely on the surface of the cylinder. The latter is identified as the integrated local energy density of the cylindrical shell when the latter is physically expanded to have finite thickness. Inside and outside the δ-function shell, the local energy density diverges as the surface of the shell is approached; the divergence is weakest when the conformal stress tensor is used to define the energy density. A real global divergence first occurs in O(λ 3 ), as anticipated, but the proof is supplied here for the first time; this divergence is entirely associated with the surface energy and does not reflect divergences in the local energy density as the surface is approached

  18. The prince as a Jesuit, the king as an abbot. The “monastic” theme in the iconography of John II Casimir

    Directory of Open Access Journals (Sweden)

    Agnieszka Skrodzka

    2016-12-01

    Full Text Available The young Casimir Vasa was brought up at the court of his father, Sigismund III Vasa, in the atmosphere of great devotion, which made him enter the order of Jesuits. Even though he decided to leave the monastery and to take the Polish crown, he came back to the life of a monk after his abdication. The present paper presents the very few pieces of art commemorating the monastic life of John Casimir: an emblem, a medal, some prints and his tomb in Paris. All those objects demonstrate the deep piety of the king.

  19. Phenomenological quantum electrodynamics when epsilonμ=l: Theory and some applications including the Casimir effect

    International Nuclear Information System (INIS)

    Brevik, I.

    1983-01-01

    The canonical quantum theory for an electromagnetic field within an isotropic nondispersive medium, whose permittivity, epsilon, and permeability μ satisfy the condition epsilonμ=1, is developed. This condition is found to simplify the electromagnetic formalism considerably and is of interest not only to quantum electrodynamics (QED) but also to quantum chromodynamics (QDC) in view of the formal analogy existing between these two theories to the zero-order in the gauge coupling constant. After giving a survey of the general formalism, this paper discusses appropriate modifications of known experiments in optics: the Ashkin-Dziedzic pressure experiment (1973), the Barlow experiment (1912), and the levitation experiment of Ashkin (1970) and others. Finally, a calculation is given of Casimir (i.e., zero-point) surface force acting on one of two spherical interfaces separating three media from each other, under certain simplifying conditions

  20. Anomalous van der Waals-Casimir interactions on graphene: A concerted effect of temperature, retardation, and non-locality

    Science.gov (United States)

    Ambrosetti, Alberto; Silvestrelli, Pier Luigi

    2018-04-01

    Dispersion forces play a major role in graphene, largely influencing adhesion of adsorbate moieties and stabilization of functional multilayered structures. However, the reliable prediction of dispersion interactions on graphene up to the relevant ˜10 nm scale is an extremely challenging task: in fact, electromagnetic retardation effects and the highly non-local character of π electrons can imply sizeable qualitative variations of the interaction with respect to known pairwise approaches. Here we address both issues, determining the finite-temperature van der Waals (vdW)-Casimir interaction for point-like and extended adsorbates on graphene, explicitly accounting for the non-local dielectric permittivity. We find that temperature, retardation, and non-locality play a crucial role in determining the actual vdW scaling laws and the stability of both atomic and larger molecular adsorbates. Our results highlight the importance of these effects for a proper description of systems of current high interest, such as graphene interacting with biomolecules, and self-assembly of complex nanoscale structures. Due to the generality of our approach and the observed non-locality of other 2D materials, our results suggest non-trivial vdW interactions from hexagonal mono-layered materials from group 14 of the periodic table, to transition metal dichalcogenides.

  1. Casimir Forces and Quantum Friction from Ginzburg Radiation in Atomic Bose-Einstein Condensates.

    Science.gov (United States)

    Marino, Jamir; Recati, Alessio; Carusotto, Iacopo

    2017-01-27

    We theoretically propose an experimentally viable scheme to use an impurity atom in an atomic Bose-Einstein condensate, in order to realize condensed-matter analogs of quantum vacuum effects. In a suitable atomic level configuration, the collisional interaction between the impurity atom and the density fluctuations in the condensate can be tailored to closely reproduce the electric-dipole coupling of quantum electrodynamics. By virtue of this analogy, we recover and extend the paradigm of electromagnetic vacuum forces to the domain of cold atoms, showing in particular the emergence, at supersonic atomic speeds, of a novel power-law scaling of the Casimir force felt by the atomic impurity, as well as the occurrence of a quantum frictional force, accompanied by the Ginzburg emission of Bogoliubov quanta. Observable consequences of these quantum vacuum effects in realistic spectroscopic experiments are discussed.

  2. Pull-in voltage of microswitch rough plates in the presence of electromagnetic and acoustic Casimir forces

    NARCIS (Netherlands)

    Palasantzas, George

    2007-01-01

    In this work, we investigate the combined influence of electromagnetic and acoustic Casimir forces on the pull-in voltage of microswitches with self-affine rough plates. It is shown that for plate separations within the micron range the acoustic term arising from pressure fluctuations can influence

  3. Additional signature of the dynamical Casimir effect in a superconducting circuit

    International Nuclear Information System (INIS)

    Rego, Andreson L.C.; Farina, C.; Silva, Hector O.; Alves, Danilo T.

    2013-01-01

    Full text: The dynamical Casimir effect (DCE) is one of the most fascinating quantum vacuum effects that consists, essentially, on the particle creation as a result of the interaction between a quantized field and a moving mirror. In this sense, particle creation due to external time-dependent potentials or backgrounds, or even time dependent electromagnetic properties of a material medium can also be included in a general definition of DCE. For simplicity, this interaction is simulated, in general, by means of idealized boundary conditions (BC). As a consequence of the particle creation, the moving mirror experiences a dissipative radiation reaction force acting on it. In order to generate an appreciable number of photons to be observed, the DCE was investigated in other contexts, as for example, in the circuit quantum electrodynamics. This theory predicted high photon creation rate by the modulation of the length of an open transmission line coupled to a superconducting quantum interference device (SQUID), an extremely sensitive magnetometer (J.R. Johansson et al, 2009/2010). A time dependent magnetic flux can be applied to the SQUID changing its inductance, leading to a time-dependent BC which simulates a moving boundary It was in the last scenario that the first observation of the DCE was announced by Wilson and collaborators (Wilson et al, 2011). Taking as motivation the experiment that observed the DCE, we investigate the influence of the generalized time-dependent Robin BC, that presents an extra term involving the second order time derivative of the field, in the particle creation via DCE. This kind of BC may appear quite naturally in the context of circuit quantum electrodynamics and the extra term was neglected in the theoretical aspects of the first observation of the DCE. Appropriate adjustments of this new parameter can not only enhance the total number of created particles but also give rise to a non-parabolic shape of the particle creation spectral

  4. Constraints on Stable Equilibria with Fluctuation-Induced (Casimir) Forces

    International Nuclear Information System (INIS)

    Rahi, Sahand Jamal; Kardar, Mehran; Emig, Thorsten

    2010-01-01

    We examine whether fluctuation-induced forces can lead to stable levitation. First, we analyze a collection of classical objects at finite temperature that contain fixed and mobile charges and show that any arrangement in space is unstable to small perturbations in position. This extends Earnshaw's theorem for electrostatics by including thermal fluctuations of internal charges. Quantum fluctuations of the electromagnetic field are responsible for Casimir or van der Waals interactions. Neglecting permeabilities, we find that any equilibrium position of items subject to such forces is also unstable if the permittivities of all objects are higher or lower than that of the enveloping medium, the former being the generic case for ordinary materials in vacuum.

  5. Constraints on stable equilibria with fluctuation-induced (Casimir) forces.

    Science.gov (United States)

    Rahi, Sahand Jamal; Kardar, Mehran; Emig, Thorsten

    2010-08-13

    We examine whether fluctuation-induced forces can lead to stable levitation. First, we analyze a collection of classical objects at finite temperature that contain fixed and mobile charges and show that any arrangement in space is unstable to small perturbations in position. This extends Earnshaw's theorem for electrostatics by including thermal fluctuations of internal charges. Quantum fluctuations of the electromagnetic field are responsible for Casimir or van der Waals interactions. Neglecting permeabilities, we find that any equilibrium position of items subject to such forces is also unstable if the permittivities of all objects are higher or lower than that of the enveloping medium, the former being the generic case for ordinary materials in vacuum.

  6. Exact results for the behavior of the thermodynamic Casimir force in a model with a strong adsorption

    Science.gov (United States)

    Dantchev, Daniel M.; Vassilev, Vassil M.; Djondjorov, Peter A.

    2016-09-01

    When massless excitations are limited or modified by the presence of material bodies one observes a force acting between them generally called Casimir force. Such excitations are present in any fluid system close to its true bulk critical point. We derive exact analytical results for both the temperature and external ordering field behavior of the thermodynamic Casimir force within the mean-field Ginzburg-Landau Ising type model of a simple fluid or binary liquid mixture. We investigate the case when under a film geometry the boundaries of the system exhibit strong adsorption onto one of the phases (components) of the system. We present analytical and numerical results for the (temperature-field) relief map of the force in both the critical region of the film close to its finite-size or bulk critical points as well as in the capillary condensation regime below but close to the finite-size critical point.

  7. Casimir Energies for Isorefractive or Diaphanous Balls

    Directory of Open Access Journals (Sweden)

    Kimball A. Milton

    2018-03-01

    Full Text Available It is known that the Casimir self-energy of a homogeneous dielectric ball is divergent, although a finite self-energy can be extracted through second order in the deviation of the permittivity from the vacuum value. The exception occurs when the speed of light inside the spherical boundary is the same as that outside, so the self-energy of a perfectly conducting spherical shell is finite, as is the energy of a dielectric-diamagnetic sphere with ε μ = 1 , a so-called isorefractive or diaphanous ball. Here we re-examine that example and attempt to extend it to an electromagnetic δ -function sphere, where the electric and magnetic couplings are equal and opposite. Unfortunately, although the energy expression is superficially ultraviolet finite, additional divergences appear that render it difficult to extract a meaningful result in general, but some limited results are presented.

  8. A microscopic approach to Casimir and Casimir–Polder forces between metallic bodies

    International Nuclear Information System (INIS)

    Barcellona, Pablo; Passante, Roberto

    2015-01-01

    We consider the Casimir–Polder interaction energy between a metallic nanoparticle and a metallic plate, as well as the Casimir interaction energy between two macroscopic metal plates, in terms of the many-body dispersion interactions between their constituents. Expressions for two- and three-body dispersion interactions between the microscopic parts of a real metal are first obtained, both in the retarded and non-retarded limits. These expressions are then used to evaluate the overall two- and three-body contributions to the macroscopic Casimir–Polder and Casimir force, and to compare them with each other, for the two following geometries: metal nanoparticle/half-space and half-space/half-space, where all the materials are assumed perfect conductors. The above evaluation is obtained by summing up the contributions from the microscopic constituents of the bodies (metal nanoparticles). In the case of nanoparticle/half-space, our results fully agree with those that can be extracted from the corresponding macroscopic results, and explicitly show the non-applicability of the pairwise approximation for the geometry considered. In both cases, we find that, while the overall two-body contribution yields an attractive force, the overall three-body contribution is repulsive. Also, they turn out to be of the same order, consistently with the known non applicability of the pairwise approximation. The issue of the rapidity of convergence of the many-body expansion is also briefly discussed

  9. Energy loss mechanism for suspended micro- and nanoresonators due to the Casimir force

    OpenAIRE

    Gusso, André

    2011-01-01

    A so far not considered energy loss mechanism in suspended micro- and nanoresonators due to noncontact acoustical energy loss is investigated theoretically. The mechanism consists on the conversion of the mechanical energy from the vibratory motion of the resonator into acoustic waves on large nearby structures, such as the substrate, due to the coupling between the resonator and those structures resulting from the Casimir force acting over the separation gaps. Analytical expressions for the ...

  10. The Casimir Effect from the Point of View of Algebraic Quantum Field Theory

    Energy Technology Data Exchange (ETDEWEB)

    Dappiaggi, Claudio, E-mail: claudio.dappiaggi@unipv.it; Nosari, Gabriele [Università degli Studi di Pavia, Dipartimento di Fisica (Italy); Pinamonti, Nicola [Università di Genova, Dipartimento di Matematica (Italy)

    2016-06-15

    We consider a region of Minkowski spacetime bounded either by one or by two parallel, infinitely extended plates orthogonal to a spatial direction and a real Klein-Gordon field satisfying Dirichlet boundary conditions. We quantize these two systems within the algebraic approach to quantum field theory using the so-called functional formalism. As a first step we construct a suitable unital ∗-algebra of observables whose generating functionals are characterized by a labelling space which is at the same time optimal and separating and fulfils the F-locality property. Subsequently we give a definition for these systems of Hadamard states and we investigate explicit examples. In the case of a single plate, it turns out that one can build algebraic states via a pull-back of those on the whole Minkowski spacetime, moreover inheriting from them the Hadamard property. When we consider instead two plates, algebraic states can be put in correspondence with those on flat spacetime via the so-called method of images, which we translate to the algebraic setting. For a massless scalar field we show that this procedure works perfectly for a large class of quasi-free states including the Poincaré vacuum and KMS states. Eventually Wick polynomials are introduced. Contrary to the Minkowski case, the extended algebras, built in globally hyperbolic subregions can be collected in a global counterpart only after a suitable deformation which is expressed locally in terms of a *-isomorphism. As a last step, we construct explicitly the two-point function and the regularized energy density, showing, moreover, that the outcome is consistent with the standard results of the Casimir effect.

  11. Casimir Energy of the Nambu-Goto String with Gauss-Bonnet Term and Point-Like Masses at the Ends

    Science.gov (United States)

    Hadasz, Leszek

    1999-09-01

    We calculate the Casimir energy of the rotating Nambu-Goto string with the Gauss-Bonnet term in the action and point-like masses at the ends. This energy turns out to be negative for every values of the parameters of the model.

  12. Casimir Energy of the Nambu-Goto String with Gauss-Bonnet Term and Point-Like Masses at the Ends

    International Nuclear Information System (INIS)

    Hadasz, L.

    1999-01-01

    We calculate the Casimir energy of the rotating Nambu-Goto string with the Gauss-Bonnet term in the action and point-like masses at the ends. This energy turns out to be negative for every values of the parameters of the model. (author)

  13. Lifshitz-Matsubara sum formula for the Casimir pressure between magnetic metallic mirrors

    Science.gov (United States)

    Guérout, R.; Lambrecht, A.; Milton, K. A.; Reynaud, S.

    2016-02-01

    We examine the conditions of validity for the Lifshitz-Matsubara sum formula for the Casimir pressure between magnetic metallic plane mirrors. As in the previously studied case of nonmagnetic materials [Guérout et al., Phys. Rev. E 90, 042125 (2014), 10.1103/PhysRevE.90.042125], we recover the usual expression for the lossy model of optical response, but not for the lossless plasma model. We also show that the modes associated with the Foucault currents play a crucial role in the limit of vanishing losses, in contrast to expectations.

  14. Casimir energy of the Nambu-Goto string with Gauss-Bonnet term and point-like masses at the ends

    OpenAIRE

    Hadasz, Leszek

    1999-01-01

    We calculate (using zeta function regularization) the Casimir energy of the rotating Nambu-Goto string with the Gauss-Bonnet term in the action and point-like masses at the ends. The resulting value turns out to be negative for all values of the parameters of the model.

  15. Dynamics of the Vacuum and Casimir Analogs to the Hydrogen Atom

    Science.gov (United States)

    White, Harold; Vera, Jerry; Bailey, Paul; March, Paul; Lawrence, Tim; Sylvester, Andre; Brady, David

    2015-01-01

    This paper will discuss the current viewpoint of the vacuum state and explore the idea of a "natural" vacuum as opposed to immutable, non-degradable vacuum. This concept will be explored for all primary quantum numbers to show consistency with observation at the level of Bohr theory. A comparison with the Casimir force per unit area will be made, and an explicit function for the spatial variation of the vacuum density around the atomic nucleus will be derived. This explicit function will be numerically modeled using the industry multi-physics tool, COMSOL(trademark), and the eigenfrequencies for the n = 1 to n = 7 states will be found and compared to expectation.

  16. Casimir forces between compact objects: The scalar case

    International Nuclear Information System (INIS)

    Emig, T.; Graham, N.; Jaffe, R. L.; Kardar, M.

    2008-01-01

    We have developed an exact, general method to compute Casimir interactions between a finite number of compact objects of arbitrary shape and separation. Here, we present details of the method for a scalar field to illustrate our approach in its most simple form; the generalization to electromagnetic fields is outlined in Ref. [T. Emig, N. Graham, R. L. Jaffe, and M. Kardar, Phys. Rev. Lett. 99, 170403 (2007).]. The interaction between the objects is attributed to quantum fluctuations of source distributions on their surfaces, which we decompose in terms of multipoles. A functional integral over the effective action of multipoles gives the resulting interaction. Each object's shape and boundary conditions enter the effective action only through its scattering matrix. Their relative positions enter through universal translation matrices that depend only on field type and spatial dimension. The distinction of our method from the pairwise summation of two-body potentials is elucidated in terms of the scattering processes between three objects. To illustrate the power of the technique, we consider Robin boundary conditions φ-λ∂ n φ=0, which interpolate between Dirichlet and Neumann cases as λ is varied. We obtain the interaction between two such spheres analytically in a large separation expansion, and numerically for all separations. The cases of unequal radii and unequal λ are studied. We find sign changes in the force as a function of separation in certain ranges of λ and see deviations from the proximity force approximation even at short separations, most notably for Neumann boundary conditions

  17. Effect of intermolecular force on the static/dynamic behaviour of M/NEM devices

    Science.gov (United States)

    Kim, Namjung; Aluru, N. R.

    2014-12-01

    Advances made in the fabrication of micro/nano-electromechanical (M/NEM) devices over the last ten years necessitate the understanding of the attractive force that arises from quantum fluctuations (generally referred to as Casimir effects) [Casimir H B G 1948 Proc. K. Ned. Akad. Wet. 51 793]. The fundamental mechanisms underlying quantum fluctuations have been actively investigated through various theoretical and experimental approaches. However, the effect of the force on M/NEM devices has not been fully understood yet, especially in the transition region involving gaps ranging from 10 nm to 1 μm, due to the complexity of the force. Here, we numerically calculate the Casimir effects in M/NEM devices by using the Lifshitz formula, the general expression for the Casimir effects [Lifshitz E 1956 Sov. Phys. JETP 2 73]. Since the Casimir effects are highly dependent on the permittivity of the materials, the Kramer-Kronig relation [Landau L D, Lifshitz E M and Pitaevskii L P 1984 Electrodynamics of Continuous Media (New York: Pergamon Press)] and the optical data for metals and dielectrics are used in order to obtain the permittivity. Several simplified models for the permittivity of the materials, such as the Drude and Lorentz models [Jackson J D 1975 Classical Electrodynamics (New York: Wiley)], are also used to extrapolate the optical data. Important characteristic values of M/NEM devices, such as the pull-in voltage, pull-in gap, detachment length, etc, are calculated for devices operating in the transition region. Our results show that accurate predictions for the pull-in behaviour are possible when the Lifshitz formula is used instead of the idealized expressions for Casimir effects. We expand this study into the dynamics of M/NEM devices, so that the time and frequency response of M/NEM devices with Casimir effects can be explored.

  18. Effect of intermolecular force on the static/dynamic behaviour of M/NEM devices

    International Nuclear Information System (INIS)

    Kim, Namjung; Aluru, N R

    2014-01-01

    Advances made in the fabrication of micro/nano-electromechanical (M/NEM) devices over the last ten years necessitate the understanding of the attractive force that arises from quantum fluctuations (generally referred to as Casimir effects) [Casimir H B G 1948 Proc. K. Ned. Akad. Wet. 51 793]. The fundamental mechanisms underlying quantum fluctuations have been actively investigated through various theoretical and experimental approaches. However, the effect of the force on M/NEM devices has not been fully understood yet, especially in the transition region involving gaps ranging from 10 nm to 1 μm, due to the complexity of the force. Here, we numerically calculate the Casimir effects in M/NEM devices by using the Lifshitz formula, the general expression for the Casimir effects [Lifshitz E 1956 Sov. Phys. JETP 2 73]. Since the Casimir effects are highly dependent on the permittivity of the materials, the Kramer–Kronig relation [Landau L D, Lifshitz E M and Pitaevskii L P 1984 Electrodynamics of Continuous Media (New York: Pergamon Press)] and the optical data for metals and dielectrics are used in order to obtain the permittivity. Several simplified models for the permittivity of the materials, such as the Drude and Lorentz models [Jackson J D 1975 Classical Electrodynamics (New York: Wiley)], are also used to extrapolate the optical data. Important characteristic values of M/NEM devices, such as the pull-in voltage, pull-in gap, detachment length, etc, are calculated for devices operating in the transition region. Our results show that accurate predictions for the pull-in behaviour are possible when the Lifshitz formula is used instead of the idealized expressions for Casimir effects. We expand this study into the dynamics of M/NEM devices, so that the time and frequency response of M/NEM devices with Casimir effects can be explored. (paper)

  19. Irreversible dynamics, Onsager-Casimir symmetry, and an application to turbulence.

    Science.gov (United States)

    Ottinger, Hans Christian

    2014-10-01

    Irreversible contributions to the dynamics of nonequilibrium systems can be formulated in terms of dissipative, or irreversible, brackets. We discuss the structure of such irreversible brackets in view of a degeneracy implied by energy conservation, where we consider different types of symmetries of the bracket corresponding to the Onsager and Casimir symmetries of linear irreversible thermodynamics. Slip and turbulence provide important examples of antisymmetric irreversible brackets and offer guidance for the more general modeling of irreversible dynamics without entropy production. Conversely, turbulence modeling could benefit from elucidating thermodynamic structure. The examples suggest constructing antisymmetric irreversible brackets in terms of completely antisymmetric functions of three indices. Irreversible brackets without well-defined symmetry properties can arise for rare events, causing big configurational changes.

  20. Geometric Approach to Quantum Statistical Mechanics and Application to Casimir Energy and Friction Properties

    International Nuclear Information System (INIS)

    Ichinose, Shoichi

    2010-01-01

    A geometric approach to general quantum statistical systems (including the harmonic oscillator) is presented. It is applied to Casimir energy and the dissipative system with friction. We regard the (N+1)-dimensional Euclidean coordinate system (X i ,τ) as the quantum statistical system of N quantum (statistical) variables (X τ ) and one Euclidean time variable (t). Introducing paths (lines or hypersurfaces) in this space (X τ ,t), we adopt the path-integral method to quantize the mechanical system. This is a new view of (statistical) quantization of the mechanical system. The system Hamiltonian appears as the area. We show quantization is realized by the minimal area principle in the present geometric approach. When we take a line as the path, the path-integral expressions of the free energy are shown to be the ordinary ones (such as N harmonic oscillators) or their simple variation. When we take a hyper-surface as the path, the system Hamiltonian is given by the area of the hyper-surface which is defined as a closed-string configuration in the bulk space. In this case, the system becomes a O(N) non-linear model. We show the recently-proposed 5 dimensional Casimir energy (ArXiv:0801.3064,0812.1263) is valid. We apply this approach to the visco-elastic system, and present a new method using the path-integral for the calculation of the dissipative properties.

  1. Casimir friction between polarizable particle and half-space with radiation damping at zero temperature

    International Nuclear Information System (INIS)

    Høye, J S; I Brevik; Milton, K A

    2015-01-01

    Casimir friction between a polarizable particle and a semi-infinite space is a delicate physical phenomenon, as it concerns the interaction between a microscopic quantum particle and a semi-infinite reservoir. Not unexpectedly, results obtained in the past about the friction force obtained via different routes are sometimes, at least apparently, wildly different from each other. Recently, we considered the Casimir friction force for two dielectric semi-infinite plates moving parallel to each other Høye and Brevik (2014 Eur. Phys. J. D 68 61), and managed to get essential agreement with results obtained by Pendry (1997 J. Phys.: Condens. Matter 9 10301), Volokitin and Persson (2007 Rev. Mod. Phys. 79 1291), and Barton (2011 New J. Phys. 13 043023; 2011 J. Phys.: Condens. Matter 23 335004). Our method was based upon use of the Kubo formalism. In the present paper we focus on the interaction between a polarizable particle and a dielectric half-space again, and calculate the friction force using the same basic method as before. The new ingredient in the present analysis is that we take into account radiative damping, and derive the modifications thereof. Some comparisons are also made with works from others. Essential agreement with the results of Intravaia, Behunin, and Dalvit can also be achieved using the modification of the atomic polarizability by the metallic plate. (paper)

  2. Casimir interaction between gas media of excited atoms

    International Nuclear Information System (INIS)

    Sherkunov, Yury

    2007-01-01

    The retarded dispersion interaction (Casimir interaction) between two dilute dielectric media at high temperatures is considered. The excited atoms are taken into account. It is shown that the perturbation technique cannot be applied to this problem due to divergence of integrals. A non-perturbative approach based on kinetic Green functions is implemented. We consider the interaction between two atoms (one of them is excited) embedded in an absorbing dielectric medium. We take into account the possible absorption of photons in the medium, which solves the problem of divergence. The force between two plane dilute dielectric media is calculated at pair interaction approximation. We show that the result of quantum electrodynamics differs from the Lifshitz formula for dilute gas media at high temperatures (if the number of excited atoms is significant). According to quantum electrodynamics, the interaction may be either attractive or repulsive depending on the temperature and the density numbers of the media

  3. Derivation of the Lifshitz-Matsubara sum formula for the Casimir pressure between metallic plane mirrors

    Science.gov (United States)

    Guérout, R.; Lambrecht, A.; Milton, K. A.; Reynaud, S.

    2014-10-01

    We carefully reexamine the conditions of validity for the consistent derivation of the Lifshitz-Matsubara sum formula for the Casimir pressure between metallic plane mirrors. We recover the usual expression for the lossy Drude model but not for the lossless plasma model. We give an interpretation of this new result in terms of the modes associated with the Foucault currents, which play a role in the limit of vanishing losses, in contrast to common expectations.

  4. Three-body radiative heat transfer and Casimir-Lifshitz force out of thermal equilibrium for arbitrary bodies

    Science.gov (United States)

    Messina, Riccardo; Antezza, Mauro

    2014-05-01

    We study the Casimir-Lifshitz force and the radiative heat transfer in a system consisting of three bodies held at three independent temperatures and immersed in a thermal environment, the whole system being in a stationary configuration out of thermal equilibrium. The theory we develop is valid for arbitrary bodies, i.e., for any set of temperatures, dielectric, and geometrical properties, and describes each body by means of its scattering operators. For the three-body system we provide a closed-form unified expression of the radiative heat transfer and of the Casimir-Lifshitz force (both in and out of thermal equilibrium). This expression is thus first applied to the case of three planar parallel slabs. In this context we discuss the nonadditivity of the force at thermal equilibrium, as well as the equilibrium temperature of the intermediate slab as a function of its position between two external slabs having different temperatures. Finally, we consider the force acting on an atom inside a planar cavity. We show that, differently from the equilibrium configuration, the absence of thermal equilibrium admits one or more positions of minima for the atomic potential. While the corresponding atomic potential depths are very small for typical ground-state atoms, they may become particularly relevant for Rydberg atoms, becoming a promising tool to produce an atomic trap.

  5. Casimir quantum levitation tuned by means of material properties and geometries

    Science.gov (United States)

    Dou, Maofeng; Lou, Fei; Boström, Mathias; Brevik, Iver; Persson, Clas

    2014-05-01

    The Casimir force between two surfaces is attractive in most cases. Although stable suspension of nano-objects has been achieved, the sophisticated geometries make them difficult to be merged with well-established thin film processes. We find that by introducing thin film surface coating on porous substrates, a repulsive to attractive force transition is achieved when the separations are increased in planar geometries, resulting in a stable suspension of two surfaces near the force transition separation. Both the magnitude of the force and the transition distance can be flexibly tailored though modifying the properties of the considered materials, that is, thin film thickness, doping concentration, and porosity. This stable suspension can be used to design new nanodevices with ultralow friction. Moreover, it might be convenient to merge this thin film coating approach with micro- and nanofabrication processes in the future.

  6. Anharmonic 1D actuator model including electrostatic and Casimir forces with fractional damping perturbed by an external force

    Science.gov (United States)

    Mansoori Kermani, Maryam; Dehestani, Maryam

    2018-06-01

    We modeled a one-dimensional actuator including the Casimir and electrostatic forces perturbed by an external force with fractional damping. The movable electrode was assumed to oscillate by an anharmonic elastic force originated from Murrell-Mottram or Lippincott potential. The nonlinear equations have been solved via the Adomian decomposition method. The behavior of the displacement of the electrode from equilibrium position, its velocity and acceleration were described versus time. Also, the changes of the displacement have been investigated according to the frequency of the external force and the voltage of the electrostatic force. The convergence of the Adomian method and the effect of the orders of expansion on the displacement versus time, frequency, and voltage were discussed. The pull-in parameter was obtained and compared with the other models in the literature. This parameter was described versus the equilibrium position and anharmonicity constant.

  7. Anharmonic 1D actuator model including electrostatic and Casimir forces with fractional damping perturbed by an external force

    Science.gov (United States)

    Mansoori Kermani, Maryam; Dehestani, Maryam

    2018-03-01

    We modeled a one-dimensional actuator including the Casimir and electrostatic forces perturbed by an external force with fractional damping. The movable electrode was assumed to oscillate by an anharmonic elastic force originated from Murrell-Mottram or Lippincott potential. The nonlinear equations have been solved via the Adomian decomposition method. The behavior of the displacement of the electrode from equilibrium position, its velocity and acceleration were described versus time. Also, the changes of the displacement have been investigated according to the frequency of the external force and the voltage of the electrostatic force. The convergence of the Adomian method and the effect of the orders of expansion on the displacement versus time, frequency, and voltage were discussed. The pull-in parameter was obtained and compared with the other models in the literature. This parameter was described versus the equilibrium position and anharmonicity constant.

  8. The combinatorics computation for Casimir operators of the symplectic Lie algebra and the application for determining the center of the enveloping algebra of a semidirect product

    International Nuclear Information System (INIS)

    Le Van Hop.

    1989-12-01

    The combinatorics computation is used to describe the Casimir operators of the symplectic Lie Algebra. This result is applied for determining the Center of the enveloping Algebra of the semidirect Product of the Heisenberg Lie Algebra and the symplectic Lie Algebra. (author). 10 refs

  9. Energy-momentum tensor for a Casimir apparatus in a weak gravitational field

    International Nuclear Information System (INIS)

    Bimonte, Giuseppe; Calloni, Enrico; Esposito, Giampiero; Rosa, Luigi

    2006-01-01

    The influence of the gravity acceleration on the regularized energy-momentum tensor of the quantized electromagnetic field between two plane-parallel conducting plates is derived. We use Fermi coordinates and work to first order in the constant acceleration parameter. A perturbative expansion, to this order, of the Green functions involved and of the energy-momentum tensor is derived by means of the covariant geodesic point-splitting procedure. In correspondence to the Green functions satisfying mixed and gauge-invariant boundary conditions, and Ward identities, the energy-momentum tensor is covariantly conserved and satisfies the expected relation between gauge-breaking and ghost parts, while a new simple formula for the trace anomaly is obtained to first order in the constant acceleration. A more systematic derivation is therefore obtained of the theoretical prediction according to which the Casimir device in a weak gravitational field will experience a tiny push in the upwards direction

  10. Vacuum energy and Casimir force in the presence of a dimensional parameter in the boundary condition

    International Nuclear Information System (INIS)

    Lebedev, S.L.

    2001-01-01

    The Hamiltonian for a scalar field that satisfies the boundary condition -∂ n φ=(1/δ)φ must include a surface potential energy. The corresponding term in the Casimir energy E-tilde C proves to be a leading one when the dimension of the region is l ∼ δ. The energy E-tilde C does not involve arbitrariness associated with regularization and is an unambiguously determined function of the field mass m, the size l, and the penetration depth δ. The inclusion of the surface term is of importance for ensuring that the derivative -∂ E-tilde C /∂l is equal to the ll component of the vacuum energy-momentum tensor. The Casimir energy E-tilde C is related to its volume component E C by a Legendre transformation where the quantity conjugate to 1/δ is the product of the vacuum surface energy and δ. If δ is negative and if h-bar/mc> vertical bar δ vertical bar, there exists a critical value l=l c (δ) above which (l>l c ) the vacuum is unstable; if a self-interaction of the form φ 4 is taken into account, this will lead to a phase transition accompanied by the formation of a condensate of the field φ. If δ=+0 or ∞ and if the dimensionalities are even, it is possible to construct a vacuum energy-momentum tensor (not only energy) that is finite over the entire space. Specially chosen counterterms leave unchanged the analytic dependence of the vacuum energy on the dimensionality of space and the character of the coordinate dependence of the energy density for x>h-bar/mc

  11. Local effects of the quantum vacuum in Lorentz-violating electrodynamics

    Science.gov (United States)

    Martín-Ruiz, A.; Escobar, C. A.

    2017-02-01

    The Casimir effect is one of the most remarkable consequences of the nonzero vacuum energy predicted by quantum field theory. In this paper we use a local approach to study the Lorentz violation effects of the minimal standard model extension on the Casimir force between two parallel conducting plates in the vacuum. Using a perturbative method similar to that used for obtaining the Born series for the scattering amplitudes in quantum mechanics, we compute, at leading order in the Lorentz-violating coefficients, the relevant Green's function which satisfies given boundary conditions. The standard point-splitting technique allow us to express the vacuum expectation value of the stress-energy tensor in terms of the Green's function. We discuss its structure in the region between the plates. We compute the renormalized vacuum stress, which is obtained as the difference between the vacuum stress in the presence of the plates and that of the vacuum. The Casimir force is evaluated in an analytical fashion by two methods: by differentiating the renormalized global energy density and by computing the normal-normal component of the renormalized vacuum stress. We compute the local Casimir energy, which is found to diverge as approaching the plates, and we demonstrate that it does not contribute to the observable force.

  12. Thermal Casimir-Polder forces on a V-type three-level atom

    Science.gov (United States)

    Xu, Chen-Ran; Xu, Jing-Ping; Al-amri, M.; Zhu, Cheng-Jie; Xie, Shuang-Yuan; Yang, Ya-Ping

    2017-09-01

    We study the thermal Casimir-Polder (CP) forces on a V-type three-level atom. The competition between the thermal effect and the quantum interference of the two transition dipoles on the force is investigated. To shed light onto the role of the quantum interference, we analyze two kinds of initial states of the atom, i.e., the superradiant state and the subradiant state. Considering the atom being in the thermal reservoir, the resonant CP force arising from the real photon emission dominates in the evolution of the CP force. Under the zero-temperature condition, the quantum interference can effectively modify the amplitude and the evolution of the force, leading to a long-time force or even the cancellation of the force. Our results reveal that in the finite-temperature case, the thermal photons can enhance the amplitude of all force elements, but have no influence on the net resonant CP force in the steady state, which means that the second law of thermodynamics still works. For the ideal degenerate V-type atom with parallel dipoles under the initial subradiant state, the robust destructive quantum interference overrides the thermal fluctuations, leading to the trapping of the atom in the subradiant state and the disappearance of the CP force. However, in terms of a realistic Zeeman atom, the thermal photons play a significant role during the evolution of the CP force. The thermal fluctuations can enhance the amplitude of the initial CP force by increasing the temperature, and weaken the influence of the quantum interference on the evolution of the CP force from the initial superradiant (subradiant) state to the steady state.

  13. Lifshitz-type formulas for graphene and single-wall carbon nanotubes: van der Waals and Casimir interactions

    International Nuclear Information System (INIS)

    Bordag, M.; Geyer, B.; Klimchitskaya, G. L.; Mostepanenko, V. M.

    2006-01-01

    Lifshitz-type formulas are obtained for the van der Waals and Casimir interaction between graphene and a material plate, graphene and an atom or a molecule, and between a single-wall carbon nanotube and a plate. The reflection properties of electromagnetic oscillations on graphene are governed by the specific boundary conditions imposed on the infinitely thin positively charged plasma sheet, carrying a continuous fluid with some mass and charge density. The obtained formulas are applied to graphene interacting with Au and Si plates, to hydrogen atoms and molecules interacting with graphene, and to single-wall carbon nanotubes interacting with Au and Si plates. The generalizations to more complicated carbon nanostructures are discussed

  14. Local and nonlocal advected invariants and helicities in magnetohydrodynamics and gas dynamics: II. Noether's theorems and Casimirs

    International Nuclear Information System (INIS)

    Webb, G M; Dasgupta, B; McKenzie, J F; Hu, Q; Zank, G P

    2014-01-01

    Conservation laws in ideal gas dynamics and magnetohydrodynamics (MHD) associated with fluid relabeling symmetries are derived using Noether's first and second theorems. Lie dragged invariants are discussed in terms of the MHD Casimirs. A nonlocal conservation law for fluid helicity applicable for a non-barotropic fluid involving Clebsch variables is derived using Noether's theorem, in conjunction with a fluid relabeling symmetry and a gauge transformation. A nonlocal cross helicity conservation law involving Clebsch potentials, and the MHD energy conservation law are derived by the same method. An Euler–Poincaré variational approach is also used to derive conservation laws associated with fluid relabeling symmetries using Noether's second theorem. (paper)

  15. Obtainment of internal labelling operators as broken Casimir operators by means of contractions related to reduction chains in semisimple Lie algebras

    International Nuclear Information System (INIS)

    Campoamor-Stursberg, R

    2008-01-01

    We show that the Inoenue-Wigner contraction naturally associated to a reduction chain s implies s' of semisimple Lie algebras induces a decomposition of the Casimir operators into homogeneous polynomials, the terms of which can be used to obtain additional mutually commuting missing label operators for this reduction. The adjunction of these scalars that are no more invariants of the contraction allow to solve the missing label problem for those reductions where the contraction provides an insufficient number of labelling operators.

  16. Casimir meets Poisson: improved quark/gluon discrimination with counting observables

    Science.gov (United States)

    Frye, Christopher; Larkoski, Andrew J.; Thaler, Jesse; Zhou, Kevin

    2017-09-01

    Charged track multiplicity is among the most powerful observables for discriminating quark- from gluon-initiated jets. Despite its utility, it is not infrared and collinear (IRC) safe, so perturbative calculations are limited to studying the energy evolution of multiplicity moments. While IRC-safe observables, like jet mass, are perturbatively calculable, their distributions often exhibit Casimir scaling, such that their quark/gluon discrimination power is limited by the ratio of quark to gluon color factors. In this paper, we introduce new IRC-safe counting observables whose discrimination performance exceeds that of jet mass and approaches that of track multiplicity. The key observation is that track multiplicity is approximately Poisson distributed, with more suppressed tails than the Sudakov peak structure from jet mass. By using an iterated version of the soft drop jet grooming algorithm, we can define a "soft drop multiplicity" which is Poisson distributed at leading-logarithmic accuracy. In addition, we calculate the next-to-leading-logarithmic corrections to this Poisson structure. If we allow the soft drop groomer to proceed to the end of the jet branching history, we can define a collinear-unsafe (but still infrared-safe) counting observable. Exploiting the universality of the collinear limit, we define generalized fragmentation functions to study the perturbative energy evolution of collinear-unsafe multiplicity.

  17. De vette jaren: de Commissie-Casimir en het Nederlandse wetenschapsbeleid 1957-1970

    Directory of Open Access Journals (Sweden)

    David Baneke

    2012-11-01

    Full Text Available The Years of Abundance: the Casimir Committee and Dutch Science Policy 1957–1970 In October 1958, a committee of six prominent Dutch scientists and industrial managers presented a brief report in which they requested a major increase of the science budget. This report has been described as a turning point in the history of science in the Netherlands, signaling the beginning of a decade of rapid growth of funding for ‘pure’ research. Surprisingly little is known about the backgrounds of this report, however. In this paper, I analyze its origin, its relation to contemporary higher education policy, and its consequences. As it turns out, the report was less revolutionary than is usually assumed: it mostly reinforced developments that had already begun earlier. Furthermore, Sputnik and the Cold War were not as important as is often claimed. This paper also suggests a reinterpretation of the justification of the government spending on academic research after the Second World War. Producing skilled researchers for industry was at least as important as produc- ing new knowledge.

  18. Fermions on the low-buckled honey-comb structured lattice plane and classical Casimir-Polder force

    Science.gov (United States)

    Goswami, Partha

    2016-05-01

    We start with the well-known expression for the vacuum polarization and suitably modify it for 2+1-dimensional spin-orbit coupled (SOC) fermions on the low-buckled honey-comb structured lattice plane described by the low-energy Liu-Yao-Feng-Ezawa (LYFE) model Hamiltonian involving the Dirac matrices in the chiral representation obeying the Clifford algebra. The silicene and germanene fit this description suitably. They have the Dirac cones similar to those of graphene and SOC is much stronger. The system could be normal or ferromagnetic in nature. The silicene turns into the latter type if there is exchange field arising due to the proximity coupling to a ferromagnet (FM) such as depositing Fe atoms to the silicene surface. For the silicene, we find that the many-body effects considerably change the bare Coulomb potential by way of the dependence of the Coulomb propagator on the real-spin, iso-spin and the potential due to an electric field applied perpendicular to the silicene plane. The computation aspect of the Casimir-Polder force (CPF) needs to be investigated in this paper. An important quantity in this process is the dielectric response function (DRF) of the material. The plasmon branch was obtained by finding the zeros of DRF in the long-wavelength limit. This leads to the plasmon frequencies. We find that the collective charge excitations at zero doping, i.e., intrinsic plasmons, in this system, are absent in the Dirac limit. The valley-spin-split intrinsic plasmons, however, come into being in the case of the massive Dirac particles with characteristic frequency close to 10 THz. Our scheme to calculate the Casimir-Polder interaction (CPI) of a micro-particle with a sheet involves replacing the dielectric constant of the sample in the CPI expression obtained on the basis of the Lifshitz theory by the static DRF obtained using the expressions for the polarization function we started with. Though the approach replaces a macroscopic constant by a microscopic

  19. Quantum reflection times and space shifts for Casimir-van der Waals potential tails

    International Nuclear Information System (INIS)

    Jurisch, Alexander; Friedrich, Harald

    2004-01-01

    When cold atoms approach a surface, they can be quantum reflected by quantal regions in the tail of the atom-surface potential. We study the phase of the reflection amplitude for Casimir-van der Waals potential tails, depending on the critical parameter ρ=ρ(C 3 ,C 4 ), which describes the relative importance of the -C 3 /r 3 and -C 4 /r 4 parts of the potential. The phase is related to observable kinematic quantities, the space and time shifts, the reflected atom experiences. We study three different models for the shape of the potential between the asymptotic limits and observe that the phases are more sensitive to the potential shape than the quantum reflection probabilities. At threshold, there are always time delays in comparison to the free movement. This is in contrast to the classical movement, which shows time gains. Further above threshold, the quantum reflected atom experiences a time gain relative to free motion, but this time gain is generally smaller than that of the classical particle

  20. Casimir squared correction to the standard rotator Hamiltonian for the O( n) sigma-model in the delta-regime

    Science.gov (United States)

    Niedermayer, F.; Weisz, P.

    2018-05-01

    In a previous paper we found that the isospin susceptibility of the O( n) sigma-model calculated in the standard rotator approximation differs from the next-to-next-to leading order chiral perturbation theory result in terms vanishing like 1 /ℓ, for ℓ = L t /L → ∞ and further showed that this deviation could be described by a correction to the rotator spectrum proportional to the square of the quadratic Casimir invariant. Here we confront this expectation with analytic nonperturbative results on the spectrum in 2 dimensions, by Balog and Hegedüs for n = 3 , 4 and by Gromov, Kazakov and Vieira for n = 4, and find good agreement in both cases. We also consider the case of 3 dimensions.

  1. Casimir force, excess free energy and C-function in O(n) systems with long-range interactions in the n → ∞ limit

    International Nuclear Information System (INIS)

    Chamati, H.; Dantchev, D.M.

    2004-06-01

    We present exact results on the behavior of the thermodynamic Casimir force and the excess free energy and the C-function in the framework of the d-dimensional spherical model with a power law long-range interaction decaying at large distances r as r -d- σ, where σ c , as well as for T > Tc and T c . The universal finite-size scaling function governing the behavior of the force in the critical region is derived and its asymptotics are investigated. While in the critical and under -d -d-, critical region the force is of the order of L -d , for T > T c it decays as L -dσ , where L is the thickness of the film. We consider both the case of a finite system that has no phase transition of its own, when d - σ when one observes a dimensional crossover from d to a d - 1 dimensional critical behavior. The behavior of the force along the phase coexistence line for a magnetic field H = 0 and T c . is also derived. We have proven analytically that the excess free energy is always negative ad monotonically increasing function of T and H, while the C-function is always non-negative and monotonically decreasing function of T and H. For the Casimir force we have demonstrated that for any σ > it is everywhere negative, i.e. an attraction between the surfaces bounding the system is to be observed. At T = T c the force is an increasing function of T for σ > 1 and a decreasing one for σ c is always achieved at some H ≠ 0 . (author)

  2. Generalized closed form solutions for feasible dimension limit and pull-in characteristics of nanocantilever under the Influences of van der Waals and Casimir forces

    Science.gov (United States)

    Mukherjee, Banibrata; Sen, Siddhartha

    2018-04-01

    This paper presents generalized closed form expressions for determining the dimension limit for the basic design parameters as well as the pull-in characteristics of a nanocantilever beam under the influences of van der Waals and Casimir forces. The coupled nonlinear electromechanical problem of electrostatic nanocantilever is formulated in nondimensional form with Galerkin’s approximation considering the effects of these intermolecular forces and fringe field. The resulting integrals and higher order polynomials are solved numerically to derive the closed form expressions for maximum permissible detachment length, minimum feasible gap spacing and critical pull-in limit. The derived expressions are compared and validated as well with several reported literature showing reasonable agreement. The major advantages of the proposed closed form expressions are that, they do not contain any complex mathematical term or operation unlike in reported literature and thus they will serve as convenient tools for the NEMS community in successful design of various electrostatically actuated nanosystems.

  3. Dependence of the Casimir-Polder interaction between an atom and a cavity wall on atomic and material properties

    International Nuclear Information System (INIS)

    Mostepanenko, V M; Babb, J F; Caride, A O; Klimchitskaya, G L; Zanette, S I

    2006-01-01

    The Casimir-Polder and van der Waals interactions between an atom and a flat cavity wall are investigated under the influence of real conditions including the dynamic polarizability of the atom, actual conductivity of the wall material and nonzero temperature of the wall. The cases of different atoms near metal and dielectric walls are considered. It is shown that to obtain accurate results for the atom-wall interaction at short separations, one should use the complete tabulated optical data for the complex refractive index of the wall material and the accurate dynamic polarizability of an atom. At relatively large separations in the case of a metal wall, one may use the plasma model dielectric function to describe the dielectric properties of the wall material. The obtained results are important for the theoretical interpretation of experiments on quantum reflection and Bose-Einstein condensation

  4. Radion effective potential in the brane-world

    International Nuclear Information System (INIS)

    Garriga, Jaume; Pujolas, Oriol; Tanaka, Takahiro

    2001-01-01

    We show that in brane-world scenarios with warped extra dimensions, the Casimir force due to bulk matter fields may be sufficient to stabilize the radion field phi. In particular, we calculate one loop effective potential for phi induced by bulk gravitons and other possible massless bulk fields in the Randall-Sundrum background. This potential has a local extremum, which can be a maximum or a minimum depending on the detailed bulk matter content. If the parameters of the background are chosen so that the hierarchy problem is solved geometrically, then the radion mass induced by Casimir corrections is hierarchically smaller than the TeV. Hence, in this important case, we must invoke an alternative mechanism (classical or nonperturbative) which gives the radion a sizable mass, to make it compatible with observations

  5. Radion effective potential in the brane-world

    Energy Technology Data Exchange (ETDEWEB)

    Garriga, Jaume E-mail: garriga@ifae.es; Pujolas, Oriol; Tanaka, Takahiro

    2001-07-02

    We show that in brane-world scenarios with warped extra dimensions, the Casimir force due to bulk matter fields may be sufficient to stabilize the radion field phi. In particular, we calculate one loop effective potential for phi induced by bulk gravitons and other possible massless bulk fields in the Randall-Sundrum background. This potential has a local extremum, which can be a maximum or a minimum depending on the detailed bulk matter content. If the parameters of the background are chosen so that the hierarchy problem is solved geometrically, then the radion mass induced by Casimir corrections is hierarchically smaller than the TeV. Hence, in this important case, we must invoke an alternative mechanism (classical or nonperturbative) which gives the radion a sizable mass, to make it compatible with observations.

  6. Quantum electrodynamics based on self-energy, without second quantization: The Lamb shift and long-range Casimir-Polder van der Waals forces near boundaries

    International Nuclear Information System (INIS)

    Barut, A.O.; Dowling, J.P.

    1986-12-01

    Using a previously formulated theory of quantum electrodynamics based on self-energy, we give a general method for computing the Lamb shift and related Casimir-Polder energies for a quantum system in the vicinity of perfectly conducting boundaries. Our results are exact and easily extendable to a full covariant relativistic form. As a particular example we apply the method to an atom near an infinite conducting plane, and we recover the standard QED results (which are known only in the dipole approximation) in a simple and straightforward manner. This is accomplished in the context of the new theory which is not second quantized and contains no vacuum fluctuations. (author)

  7. A theoretical model for investigating the effect of vacuum fluctuations on the electromechanical stability of nanotweezers

    Science.gov (United States)

    Farrokhabadi, A.; Mokhtari, J.; Koochi, A.; Abadyan, M.

    2015-06-01

    In this paper, the impact of the Casimir attraction on the electromechanical stability of nanowire-fabricated nanotweezers is investigated using a theoretical continuum mechanics model. The Dirichlet mode is considered and an asymptotic solution, based on path integral approach, is applied to consider the effect of vacuum fluctuations in the model. The Euler-Bernoulli beam theory is employed to derive the nonlinear governing equation of the nanotweezers. The governing equations are solved by three different approaches, i.e. the modified variation iteration method, generalized differential quadrature method and using a lumped parameter model. Various perspectives of the problem, including the comparison with the van der Waals force regime, the variation of instability parameters and effects of geometry are addressed in present paper. The proposed approach is beneficial for the precise determination of the electrostatic response of the nanotweezers in the presence of Casimir force.

  8. Sign change in the net force in sphere-plate and sphere-sphere systems immersed in nonpolar critical fluid due to the interplay between the critical Casimir and dispersion van der Waals forces.

    Science.gov (United States)

    Valchev, Galin; Dantchev, Daniel

    2017-08-01

    We study systems in which both long-ranged van der Waals and critical Casimir interactions are present. The latter arise as an effective force between bodies when immersed in a near-critical medium, say a nonpolar one-component fluid or a binary liquid mixture. They are due to the fact that the presence of the bodies modifies the order parameter profile of the medium between them as well as the spectrum of its allowed fluctuations. We study the interplay between these forces, as well as the total force (TF) between a spherical colloid particle and a thick planar slab and between two spherical colloid particles. We do that using general scaling arguments and mean-field-type calculations utilizing the Derjaguin and the surface integration approaches. They both are based on data of the forces between two parallel slabs separated at a distance L from each other, confining the fluctuating fluid medium characterized by its temperature T and chemical potential μ. The surfaces of the colloid particles and the slab are coated by thin layers exerting strong preference to the liquid phase of the fluid, or one of the components of the mixture, modeled by strong adsorbing local surface potentials, ensuring the so-called (+,+) boundary conditions. On the other hand, the core region of the slab and the particles influence the fluid by long-ranged competing dispersion potentials. We demonstrate that for a suitable set of colloids-fluid, slab-fluid, and fluid-fluid coupling parameters, the competition between the effects due to the coatings and the core regions of the objects involved result, when one changes T, μ, or L, in sign change of the Casimir force (CF) and the TF acting between the colloid and the slab, as well as between the colloids. This can be used for governing the behavior of objects, say colloidal particles, at small distances, say in colloid suspensions for preventing flocculation. It can also provide a strategy for solving problems with handling, feeding

  9. Sign change in the net force in sphere-plate and sphere-sphere systems immersed in nonpolar critical fluid due to the interplay between the critical Casimir and dispersion van der Waals forces

    Science.gov (United States)

    Valchev, Galin; Dantchev, Daniel

    2017-08-01

    We study systems in which both long-ranged van der Waals and critical Casimir interactions are present. The latter arise as an effective force between bodies when immersed in a near-critical medium, say a nonpolar one-component fluid or a binary liquid mixture. They are due to the fact that the presence of the bodies modifies the order parameter profile of the medium between them as well as the spectrum of its allowed fluctuations. We study the interplay between these forces, as well as the total force (TF) between a spherical colloid particle and a thick planar slab and between two spherical colloid particles. We do that using general scaling arguments and mean-field-type calculations utilizing the Derjaguin and the surface integration approaches. They both are based on data of the forces between two parallel slabs separated at a distance L from each other, confining the fluctuating fluid medium characterized by its temperature T and chemical potential μ . The surfaces of the colloid particles and the slab are coated by thin layers exerting strong preference to the liquid phase of the fluid, or one of the components of the mixture, modeled by strong adsorbing local surface potentials, ensuring the so-called (+,+) boundary conditions. On the other hand, the core region of the slab and the particles influence the fluid by long-ranged competing dispersion potentials. We demonstrate that for a suitable set of colloids-fluid, slab-fluid, and fluid-fluid coupling parameters, the competition between the effects due to the coatings and the core regions of the objects involved result, when one changes T , μ , or L , in sign change of the Casimir force (CF) and the TF acting between the colloid and the slab, as well as between the colloids. This can be used for governing the behavior of objects, say colloidal particles, at small distances, say in colloid suspensions for preventing flocculation. It can also provide a strategy for solving problems with handling, feeding

  10. Study of atomic states in the vicinity of a massive surface - Application to the FORCA-G experiment

    International Nuclear Information System (INIS)

    Pelisson, Sophie

    2012-01-01

    This thesis presents the theoretical modeling of the experiment FORCA-G (FORce de CAsimir et Gravitation a courte distance) currently in progress at Paris Observatory. The purpose of this experiment is to measure short-range interactions between an atom and a massive surface. This interaction are of two kind: quantum electrodynamical (Casimir-Polder effect) and gravitational. The work presented here was to calculate the atomic states in the context of the experiment such that we can predict results and performances of the experiment. This has allowed to optimize the experimental scheme both for the high-precision measurement of the Casimir-Polder effect and for the search of deviation from the Newton's law of gravity predicted by unification theories. (author)

  11. Geometrical Dynamics in a Transitioning Superconducting Sphere

    Directory of Open Access Journals (Sweden)

    Claycomb J. R.

    2006-10-01

    Full Text Available Recent theoretical works have concentrated on calculating the Casimir effect in curved spacetime. In this paper we outline the forward problem of metrical variation due to the Casimir effect for spherical geometries. We consider a scalar quantum field inside a hollow superconducting sphere. Metric equations are developed describing the evolution of the scalar curvature after the sphere transitions to the normal state.

  12. Grain size and nanoscale effects on the nonlinear pull-in instability and vibrations of electrostatic actuators made of nanocrystalline material

    Science.gov (United States)

    Gholami, R.; Ansari, R.

    2018-01-01

    Presented herein is the study of grain size, grain surface energy and small scale effects on the nonlinear pull-in instability and free vibration of electrostatic nanoscale actuators made of nanocrystalline silicon (Nc-Si). A Mori-Tanaka micromechanical model is utilized to calculate the effective material properties of Nc-Si considering material structure inhomogeneity, grain size and grain surface energy. The small-scale effect is also taken into account using Mindlin’s strain gradient theory. Governing equations are derived in the discretized weak form using the variational differential quadrature method based on the third-order shear defamation beam theory in conjunction with the von Kármán hypothesis. The electrostatic actuation is modeled considering the fringing field effects based upon the parallel plate approximation. Moreover, the Casimir force effect is considered. The pseudo arc-length continuation technique is used to obtain the applied voltage-deflection curve of Nc-Si actuators. Then, a time-dependent small disturbance around the deflected configuration is assumed to solve the free vibration problem. By performing a numerical study, the influences of various factors such as length scale parameter, volume fraction of the inclusion phase, density ratio, average inclusion radius and Casimir force on the pull-in instability and free vibration of Nc-Si actuators are investigated.

  13. Thixotropic Phenomena in Water: Quantitative Indicators of Casimir-Magnetic Transformations from Vacuum Oscillations (Virtual Particles

    Directory of Open Access Journals (Sweden)

    Michael A. Persinger

    2015-09-01

    Full Text Available The ~1.5 × 10−20 J which is considered a universal quantity and is associated with the movement of protons in water also relates to the ratio of the magnetic moment of a proton divided by its unit charge, multiplied by viscosity and applied over the O-H distance. There is quantitative evidence that thixotropy, the “spontaneous” increased viscosity in water when undisturbed, originates from the transformation of virtual particles or vacuum oscillations to real states through conversion of Casimir-magnetic energies that involve the frequency of the neutral hydrogen line and the upper bound threshold value for intergalactic magnetic fields. The results indicate that ½ of a single electron orbit is real (particle and the other ½ is virtual (wave. The matter equivalent per s for virtual-to-real states for electrons in 1 mL of water with a neutral pH is consistent with the numbers of protons (H+ and the measured range of molecules in the coherent domains for both width and duration of growth and is similar to widths of intergalactic dust grains from which planets and stars may condense. The de Broglie momentum for the lower boundary of the width of coherent domains multiplied by the fine structure velocity of an electron is concurrent with the quantum when one proton is being removed from another and when the upper boundary of the rest mass of a photon is transformed by the product of velocities for putative “entanglement” and light. Theoretical and experimental results indicate that components of thixotropy, such as specific domains of intercalated water molecules, could display excess correlations over very large distances. Because the energies of the universal quantity and water converge it may be a special conduit for discrete transformations from virtual to real states.

  14. Ultrathin Metallic Coatings Can Induce Quantum Levitation between Nanosurfaces

    OpenAIRE

    Boström, Mathias; Ninham, Barry W.; Brevik, Iver; Persson, Clas; Parsons, Drew F.; Sernelius, Bo E.

    2012-01-01

    There is an attractive Casimir-Lifshitz force between two silica surfaces in a liquid (bromobenze or toluene). We demonstrate that adding an ultrathin (5-50 angstrom) metallic nanocoating to one of the surfaces results in repulsive Casimir-Lifshitz forces above a critical separation. The onset of such quantum levitation comes at decreasing separations as the film thickness decreases. Remarkably, the effect of retardation can turn attraction into repulsion. From that we explain how an ultrathi...

  15. Effective action, massive gravitons and the Cosmological Constant

    Energy Technology Data Exchange (ETDEWEB)

    Garattini, Remo [Universita degli Studi di Bergamo, Facolta di Ingegneria, Viale Marconi 5, 24044 Dalmine (Bergamo) (Italy); INFN - sezione di Milano, Via Celoria 16, Milan (Italy)

    2006-03-01

    The one loop effective action in a Schwarzschild background is here used to compute the cosmological constant in presence of massive gravitons. It is shown that the expression of the Zero Point Energy (ZPE) is equivalent to the one computed by means of a variational approach. To handle with ZPE divergences, we use the zeta function regularization. The regularization is closely related to the subtraction procedure appearing in the computation of Casimir energy in a curved background. A renormalization procedure is introduced to remove the infinities together with a renormalization group equation.

  16. Effective action, massive gravitons and the Cosmological Constant

    International Nuclear Information System (INIS)

    Garattini, Remo

    2006-01-01

    The one loop effective action in a Schwarzschild background is here used to compute the cosmological constant in presence of massive gravitons. It is shown that the expression of the Zero Point Energy (ZPE) is equivalent to the one computed by means of a variational approach. To handle with ZPE divergences, we use the zeta function regularization. The regularization is closely related to the subtraction procedure appearing in the computation of Casimir energy in a curved background. A renormalization procedure is introduced to remove the infinities together with a renormalization group equation

  17. Direct measurements of surface scattering in Si nanosheets using a microscale phonon spectrometer: implications for Casimir-limit predicted by Ziman theory.

    Science.gov (United States)

    Hertzberg, Jared B; Aksit, Mahmut; Otelaja, Obafemi O; Stewart, Derek A; Robinson, Richard D

    2014-02-12

    Thermal transport in nanostructures is strongly affected by phonon-surface interactions, which are expected to depend on the phonon's wavelength and the surface roughness. Here we fabricate silicon nanosheets, measure their surface roughness (∼ 1 nm) using atomic force microscopy (AFM), and assess the phonon scattering rate in the sheets with a novel technique: a microscale phonon spectrometer. The spectrometer employs superconducting tunnel junctions (STJs) to produce and detect controllable nonthermal distributions of phonons from ∼ 90 to ∼ 870 GHz. This technique offers spectral resolution nearly 10 times better than a thermal conductance measurement. We compare measured phonon transmission rates to rates predicted by a Monte Carlo model of phonon trajectories, assuming that these trajectories are dominated by phonon-surface interactions and using the Ziman theory to predict phonon-surface scattering rates based on surface topology. Whereas theory predicts a diffuse surface scattering probability of less than 40%, our measurements are consistent with a 100% probability. Our nanosheets therefore exhibit the so-called "Casimir limit" at a much lower frequency than expected if the phonon scattering rates follow the Ziman theory for a 1 nm surface roughness. Such a result holds implications for thermal management in nanoscale electronics and the design of nanostructured thermoelectrics.

  18. The mathematics of the Casimir effect

    International Nuclear Information System (INIS)

    Dowling, J.P.

    1987-02-01

    We show how a famous problem in theoretical physics leads to two classical formulas which allow one to compute the difference between a definite integral and an infinite sum of the same functional form f. (author). 5 refs, 3 figs

  19. A note on a boundary sine-Gordon model at the free-Fermion point

    Science.gov (United States)

    Murgan, Rajan

    2018-02-01

    We investigate the free-Fermion point of a boundary sine-Gordon model with nondiagonal boundary interactions for the ground state using auxiliary functions obtained from T  -  Q equations of a corresponding inhomogeneous open spin-\\frac{1}{2} XXZ chain with nondiagonal boundary terms. In particular, we obtain the Casimir energy. Our result for the Casimir energy is shown to agree with the result from the TBA approach. The analytical result for the effective central charge in the ultraviolet (UV) limit is also verified from the plots of effective central charge for intermediate values of volume.

  20. Critical Casimir effect in a polymer chain in supercritical solvents.

    Science.gov (United States)

    Sumi, Tomonari; Imazaki, Nobuyuki; Sekino, Hideo

    2009-03-01

    Density fluctuation effects on the conformation of a polymer chain in a supercritical solvent were investigated by performing a multiscale simulation based on the density-functional theory. We found (a) a universal swelling of the polymer chain near the critical point, irrespective of whether the polymer chain is solvophilic or solvophobic, and (b) a characteristic collapse of the polymer chain having a strong solvophilicity at a temperature slightly higher than the critical point, where the isothermal compressibility becomes less than the ideal one.

  1. A geometric theory of selective decay with applications in MHD

    International Nuclear Information System (INIS)

    Gay-Balmaz, François; Holm, Darryl D

    2014-01-01

    Modifications of the equations of ideal fluid dynamics with advected quantities are introduced that allow selective decay of either the energy h or the Casimir quantities C in the Lie–Poisson (LP) formulation. The dissipated quantity (energy or Casimir, respectively) is shown to decrease in time until the modified system reaches an equilibrium state consistent with ideal energy-Casimir equilibria, namely δ(h + C) = 0. The result holds for LP equations in general, independently of the Lie algebra and the choice of Casimir. This selective decay process is illustrated with a number of examples in 2D and 3D magnetohydrodynamics. (paper)

  2. Quantum dissipative effects in moving imperfect mirrors: Sidewise and normal motions

    International Nuclear Information System (INIS)

    Fosco, Cesar D.; Lombardo, Fernando C.; Mazzitelli, Francisco D.

    2011-01-01

    We extend our previous work on the functional approach to the dynamical Casimir effect, to compute dissipative effects due to the relative motion of two flat, parallel, imperfect mirrors in vacuum. The interaction between the internal degrees of freedom of the mirrors and the vacuum field is modeled with a nonlocal term in the vacuum field action. We consider two different situations: either the motion is 'normal', i.e., the mirrors advance or recede changing the distance a(t) between them; or it is 'parallel', namely, a remains constant, but there is a relative sliding motion of the mirrors' planes. For the latter, we show explicitly that there is a nonvanishing frictional force, even for a constant shifting speed.

  3. Boundaries immersed in a scalar quantum field

    International Nuclear Information System (INIS)

    Actor, A.A.; Bender, I.

    1996-01-01

    We study the interaction between a scalar quantum field φ(x), and many different boundary configurations constructed from (parallel and orthogonal) thin planar surfaces on which φ(x) is constrained to vanish, or to satisfy Neumann conditions. For most of these boundaries the Casimir problem has not previously been investigated. We calculate the canonical and improved vacuum stress tensors left angle T μv (x) right angle and left angle direct difference μv (x) right angle of φ(x) for each example. From these we obtain the local Casimir forces on all boundary planes. For massless fields, both vacuum stress tensors yield identical attractive local Casimir forces in all Dirichlet examples considered. This desirable outcome is not a priori obvious, given the quite different features of left angle T μv (x) right angle and left angle direct difference μv (x) right angle. For Neumann conditions, left angle T μv (x) right angle and left angle direct difference μv (x) right angle lead to attractive Casimir stresses which are not always the same. We also consider Dirichlet and Neumann boundaries immersed in a common scalar quantum field, and find that these repel. The extensive catalogue of worked examples presented here belongs to a large class of completely solvable Casimir problems. Casimir forces previously unknown are predicted, among them ones which might be measurable. (orig.)

  4. Schwinger's formula and the partition function for the bosonic and fermionic harmonic oscillators

    International Nuclear Information System (INIS)

    Albuquerque, L.C. de; Farina, C.; Rabello, S.J.

    1994-01-01

    We use Schwinger's formula, introduced by himself in the early fifties to compute effective actions for Qed, and recently applied to the Casimir effect, to obtain the partition functions for both the bosonic and fermionic harmonic oscillators. (author)

  5. Effective action in multidimensional quantum gravity and spontaneous compactification

    International Nuclear Information System (INIS)

    Bagrov, V.G.; Bukhbinder, I.L.; Odintsov, S.D.

    1987-01-01

    One-loop effective action (the Casimir energy) is obtained for a special model of multidimensional quantum gravity and several variants of the d-dimensional quantum R 2 gravity in the space M 4 xT d-4 , where M 4 is the Minkowski space and T d-4 is the (d-4)-dimensional torus. It is shown that the effective action for the conformal gravity and the R 2 gravity without cosmological and Einstein's terms lead to an instability of the classical compactification. A numerical calculation reveals that the effective action for the five-dimensional R 2 gravity with the cosmological term is compatible with a self-consistent spontaneous compactification. The one-loop effective action is also obtained for the five dimensional Einstein gravity with the antisymmetrical torsion in the space M 4 xS 1 , where S 1 is the one-dimensional sphere

  6. Effective action in multidimensional quantum gravity, and spontaneous compactification

    International Nuclear Information System (INIS)

    Bagrov, V.G.; Bukhbinder, I.L.; Odintsov, S.D.

    1987-01-01

    The one-loop effective action (Casimir energy) is obtained for a special form of model of multidimensional quantum gravity and for several variants of d-dimensional quantum R 2 -gravity on the space M 4 x T/sub d//sub -4/, where M 4 is Minkowski space and T/sub d//sub -4/ is the (d-4)-dimensional torus. It is shown that the effective action of the model of multidimensional quantum gravity and R 2 -gravity without the cosmological term and Einstein term leads to instability of the classical compactification. By a numerical calculation it is demonstrated that the effective action of five-dimensional R 2 -gravity with the cosmological term admits a self-consistent spontaneous compactification. The one-loop effective action is also found for five-dimensional Einstein gravity with antisymmetric torsion on the space M 4 x S 1 (S 1 is the one-dimensional sphere)

  7. Zero-point energy of confined fermions

    International Nuclear Information System (INIS)

    Milton, K.A.

    1980-01-01

    A closed form for the reduced Green's function of massless fermions in the interior of a spherical bag is obtained. In terms of this Green's function, the corresponding zero-point or Casimir energy is computed. It is proposed that a resulting quadratic divergence can be absorbed by renormalizing a suitable parameter in the bag model (that is, absorbed by a contact term). The residual Casimir stress is attractive, but smaller than the repulsive Casimir stress of gluons in the model. The result for the total zero-point energy is in substantial disagreement with bag model phenomenological values

  8. Casimir effects for a flat plasma sheet: II. Fields and stresses

    International Nuclear Information System (INIS)

    Barton, G

    2005-01-01

    We study the self-stresses experienced by the single plasma sheet modelled in the preceding paper, and determine the exact mean-squared Maxwell fields in vacuum around it. These are effects that probe the physics of such systems further than do the ground-state eigenvalues responsible for the cohesive energy β; in particular, unlike β they depend not only on the collective properties but also on the self-fields of the charge carriers. The classical part of the interaction between the sheet and a slowly moving charged particle follows as a byproduct. The main object is to illustrate, in simple closed or almost closed form, the consequences of imperfect (dispersive) reflectivity. The largely artificial limit of perfect reflection reduces all the results to those long familiar outside a half-space taken to reflect perfectly from the outset; but a careful examination of the approach to this limit is needed in order to resolve paradoxes associated with the surface energy, and with the mechanism which, in the limit, disjoins the two flanking half-spaces both electromagnetically and quantally

  9. The square lattice Ising model on the rectangle II: finite-size scaling limit

    Science.gov (United States)

    Hucht, Alfred

    2017-06-01

    Based on the results published recently (Hucht 2017 J. Phys. A: Math. Theor. 50 065201), the universal finite-size contributions to the free energy of the square lattice Ising model on the L× M rectangle, with open boundary conditions in both directions, are calculated exactly in the finite-size scaling limit L, M\\to∞ , T\\to Tc , with fixed temperature scaling variable x\\propto(T/Tc-1)M and fixed aspect ratio ρ\\propto L/M . We derive exponentially fast converging series for the related Casimir potential and Casimir force scaling functions. At the critical point T=Tc we confirm predictions from conformal field theory (Cardy and Peschel 1988 Nucl. Phys. B 300 377, Kleban and Vassileva 1991 J. Phys. A: Math. Gen. 24 3407). The presence of corners and the related corner free energy has dramatic impact on the Casimir scaling functions and leads to a logarithmic divergence of the Casimir potential scaling function at criticality.

  10. Diffusion of Wilson loops

    International Nuclear Information System (INIS)

    Brzoska, A.M.; Lenz, F.; Thies, M.; Negele, J.W.

    2005-01-01

    A phenomenological analysis of the distribution of Wilson loops in SU(2) Yang-Mills theory is presented in which Wilson loop distributions are described as the result of a diffusion process on the group manifold. It is shown that, in the absence of forces, diffusion implies Casimir scaling and, conversely, exact Casimir scaling implies free diffusion. Screening processes occur if diffusion takes place in a potential. The crucial distinction between screening of fundamental and adjoint loops is formulated as a symmetry property related to the center symmetry of the underlying gauge theory. The results are expressed in terms of an effective Wilson loop action and compared with various limits of SU(2) Yang-Mills theory

  11. The trace identity and the planar Casimir effect

    Indian Academy of Sciences (India)

    this paper we recall that the trace identity associated with the massless free real ... Let us now motivate the work reported here: Labelling the two terms in eq. (3) by I and J ... In contrast however, with the same model Lagrangian as in (6) below but in 1 + 1 ... below – there being none in 1 + 1 dimensions as d = 0 in this case.

  12. Topics in gauge theories and the unification of elementary particle interactions

    International Nuclear Information System (INIS)

    Srivastava, Y.N.; Vaughn, M.T.

    1992-02-01

    We report on work done by the principal investigators and their collaborators on: purely fermionic composite models, gravitational diamagnetism, dynamical Casimir effect, N-particle amplitudes for large N beyond the three approximation, and analysis of classical scalar φ 4 field theory

  13. Coupling of demixing and magnetic ordering phase transitions probed by turbidimetric measurements in a binary mixture doped with magnetic nanoparticles

    International Nuclear Information System (INIS)

    Hernandez-Diaz, Lorenzo; Hernandez-Reta, Juan Carlos; Encinas, Armando; Nahmad-Molinari, Yuri

    2010-01-01

    We present a novel study on the effect of a magnetic field applied on a binary mixture doped with magnetic nanoparticles close to its demixing transition. Turbidity measurements in the Faraday configuration show that the effect of applying an external field produces changes in the critical opalescence of the mixture that allow us to track an aggregation produced by critical Casimir forces and a reversible aggregation due to the formation of chain-like flocks in response to the external magnetic field. The observation of a crossover of the aggregation curves through optical signals is interpreted as the evolution from low to high power dispersion nuclei due to an increase in the radius of the condensation seed brought about by Casimir or magnetic interactions. Finally, evidence of an enhanced magnetocaloric effect due to the coupling between mixing and ordering phase transitions is presented which opens up a nonsolid state approach of designing refrigerating cycles and devices.

  14. Coupling of demixing and magnetic ordering phase transitions probed by turbidimetric measurements in a binary mixture doped with magnetic nanoparticles

    Science.gov (United States)

    Hernández-Díaz, Lorenzo; Hernández-Reta, Juan Carlos; Encinas, Armando; Nahmad-Molinari, Yuri

    2010-05-01

    We present a novel study on the effect of a magnetic field applied on a binary mixture doped with magnetic nanoparticles close to its demixing transition. Turbidity measurements in the Faraday configuration show that the effect of applying an external field produces changes in the critical opalescence of the mixture that allow us to track an aggregation produced by critical Casimir forces and a reversible aggregation due to the formation of chain-like flocks in response to the external magnetic field. The observation of a crossover of the aggregation curves through optical signals is interpreted as the evolution from low to high power dispersion nuclei due to an increase in the radius of the condensation seed brought about by Casimir or magnetic interactions. Finally, evidence of an enhanced magnetocaloric effect due to the coupling between mixing and ordering phase transitions is presented which opens up a nonsolid state approach of designing refrigerating cycles and devices.

  15. Coupling of demixing and magnetic ordering phase transitions probed by turbidimetric measurements in a binary mixture doped with magnetic nanoparticles

    Energy Technology Data Exchange (ETDEWEB)

    Hernandez-Diaz, Lorenzo; Hernandez-Reta, Juan Carlos; Encinas, Armando; Nahmad-Molinari, Yuri, E-mail: yuri@ifisica.uaslp.m [Instituto de Fisica, Universidad Autonoma de San Luis Potosi, Alvaro Obregon 64, 78000 San Luis Potosi (Mexico)

    2010-05-19

    We present a novel study on the effect of a magnetic field applied on a binary mixture doped with magnetic nanoparticles close to its demixing transition. Turbidity measurements in the Faraday configuration show that the effect of applying an external field produces changes in the critical opalescence of the mixture that allow us to track an aggregation produced by critical Casimir forces and a reversible aggregation due to the formation of chain-like flocks in response to the external magnetic field. The observation of a crossover of the aggregation curves through optical signals is interpreted as the evolution from low to high power dispersion nuclei due to an increase in the radius of the condensation seed brought about by Casimir or magnetic interactions. Finally, evidence of an enhanced magnetocaloric effect due to the coupling between mixing and ordering phase transitions is presented which opens up a nonsolid state approach of designing refrigerating cycles and devices.

  16. Macroscopic QED in linearly responding media and a Lorentz-Force approach to dispersion forces

    Energy Technology Data Exchange (ETDEWEB)

    Raabe, Christian

    2008-07-08

    In this thesis, a very general quantization scheme for the macroscopic electromagnetic field in arbitrary linearly responding media is presented. It offers a unified approach to QED in such media. Applying the quantization scheme, a theory of the dispersion forces on the basis of the Lorentz force is developed. By regarding the dispersion force as the (ground-state or thermal-state) expectation value of the Lorentz force that acts on appropriately defined charge and current densities, Casimir, Casimir-Polder, and van der Waals forces are united in a very natural way that makes transparent their common physical basis. Application of the theory to planar structures yields generalizations of well-known Lifschitz and Casimir-type formulas. (orig.)

  17. Macroscopic QED in linearly responding media and a Lorentz-Force approach to dispersion forces

    International Nuclear Information System (INIS)

    Raabe, Christian

    2008-01-01

    In this thesis, a very general quantization scheme for the macroscopic electromagnetic field in arbitrary linearly responding media is presented. It offers a unified approach to QED in such media. Applying the quantization scheme, a theory of the dispersion forces on the basis of the Lorentz force is developed. By regarding the dispersion force as the (ground-state or thermal-state) expectation value of the Lorentz force that acts on appropriately defined charge and current densities, Casimir, Casimir-Polder, and van der Waals forces are united in a very natural way that makes transparent their common physical basis. Application of the theory to planar structures yields generalizations of well-known Lifschitz and Casimir-type formulas. (orig.)

  18. Long Range Forces between Atomic Impurities in Liquid Helium

    International Nuclear Information System (INIS)

    Dupont-Roc, J.

    2002-01-01

    Van der Waals or Casimir interaction between neutral quantum objects in their ground state is known to be universally attractive. This is not necessarily so when these objects are embedded in a polarizable medium. We show that atomic impurities in liquid helium may indeed realize repulsive forces, and even Van der Waals and Casimir forces with different signs. (author)

  19. Stability and interactions of nanocolloids at fluid interfaces: effects of capillary waves and line tensions

    International Nuclear Information System (INIS)

    Lehle, H; Oettel, M

    2008-01-01

    We analyze the effective potential for nanoparticles trapped at a fluid interface within a simple model which incorporates surface and line tensions as well as a thermal average over interface fluctuations (capillary waves). For a single colloid, a reduced steepness of the potential well hindering movements out of the interface plane compared to rigid interface models is observed, and an instability of the capillary wave partition sum in the case of negative line tensions is pointed out. For two colloids, averaging over the capillary waves leads to an effective Casimir-type interaction which is long ranged, power-like in the inverse distance, but whose power sensitively depends on possible restrictions of the colloid degrees of freedom. A nonzero line tension leads to changes in the magnitude but not in the functional form of the effective potential asymptotics

  20. Different ways of looking at the electromagnetic vacuum

    International Nuclear Information System (INIS)

    Milonni, P.W.

    1987-01-01

    Some thoughts on the electromagnetic vacuum are presented in connection with the vacuum and source fields as alternative physical bases for understanding spontaneous emission, the Lamb shift, Casimir effects, van der Waals forces, and the ''thermalization'' of vacuum fluctuations for a uniformly accelerated observer

  1. [Gamma scattering in condensed matter with high intensity Moessbauer radiation

    International Nuclear Information System (INIS)

    1992-01-01

    This report discusses: quasielastic scattering studies on glycerol; gamma-ray scattering from alkali halides; lattice dynamics in metals; Moessbauer neutron scattering, x-ray diffraction, and macroscopic studies of high T c superconductors containing tungsten; NiAl scattering studies; and atomic interference factors and nuclear Casimir effect

  2. Influence of surface effects on the pull-in instability of NEMS electrostatic switches

    Energy Technology Data Exchange (ETDEWEB)

    Ma, Jianming Bryan; Jiang Liying; Asokanthan, Samuel F, E-mail: lyjiang@eng.uwo.ca, E-mail: sasokanthan@eng.uwo.ca [Department of Mechanical and Materials Engineering, University of Western Ontario, London, ON, N6A 5B9 (Canada)

    2010-12-17

    The influence of surface effects, including residual surface stress and surface elasticity, on the pull-in instability of electrostatic switches in nanoelectromechanical systems (NEMS) is studied using an Euler-Bernoulli beam model. This model is inherently nonlinear due to the driving electrostatic force and Casimir force which become dominant at the nanoscale. Since no exact solutions are available for the resulting nonlinear differential equation, He's homotopy perturbation method (HPM) is used to get the approximate analytical solutions to the static bending of NEMS switches, which are validated by numerical solutions of the finite difference method (FDM). The results demonstrate that surface effects play a significant role in the selection of basic design parameters of NEMS switches, such as static deflection, pull-in voltage and detachment length. Surface effects on low-voltage actuation windows are also characterized for these switches. The present study is envisaged to provide useful insights for the design of NEMS switches.

  3. Quantum effects of a massive 3-form coupled to a Dirac field

    International Nuclear Information System (INIS)

    Aurilia, Antonio; Spallucci, Euro

    2004-01-01

    The computation of the quantum vacuum pressure must take into account the contribution of zero-point oscillations of a rank-three gauge field A μνρ . This result was established in a previous paper where we calculated both the Casimir pressure within a region of vacuum simulating a hadronic bag and the Wilson factor for the three-index potential associated with the boundary of the bag. The resulting 'volume law' satisfied by the Wilson loop is consistent with the basic confining requirement that the static interquark potential increases with the distance between two test charges. As a sequel to that paper, we consider here the coupling of A μνρ to the generic current of a matter field, later identified with the spin density current of a Dirac field. In fact, one of the objectives of this paper is to investigate the impact of the quantum fluctuations of A μνρ on the effective dynamics of the spinor field. The consistency of the field equations, even at the classical level, requires the introduction of a mass term for A μνρ . In this case, the Casimir vacuum pressure includes a contribution that is explicitly dependent on the mass of A μνρ and leads us to conclude that the mass term plays the same role as the infrared cutoff needed to regularize the finite volume partition functional previously calculated in the massless case. Remarkably, even in the presence of a mass term, A μνρ contains a mixture of massless and massive spin-0 fields so that the resulting equation is still gauge invariant. This is yet another peculiar, but physically relevant property of A μνρ since it is reflected in the effective dynamics of the spinor fields and confirms the confining property of A μνρ already expected from the earlier calculation of the Wilson loop

  4. Electronic zero-point fluctuation forces inside circuit components

    Science.gov (United States)

    Leonhardt, Ulf

    2018-01-01

    One of the most intriguing manifestations of quantum zero-point fluctuations are the van der Waals and Casimir forces, often associated with vacuum fluctuations of the electromagnetic field. We study generalized fluctuation potentials acting on internal degrees of freedom of components in electrical circuits. These electronic Casimir-like potentials are induced by the zero-point current fluctuations of any general conductive circuit. For realistic examples of an electromechanical capacitor and a superconducting qubit, our results reveal the possibility of tunable forces between the capacitor plates, or the level shifts of the qubit, respectively. Our analysis suggests an alternative route toward the exploration of Casimir-like fluctuation potentials, namely, by characterizing and measuring them as a function of parameters of the environment. These tunable potentials may be useful for future nanoelectromechanical and quantum technologies. PMID:29719863

  5. Electronic zero-point fluctuation forces inside circuit components.

    Science.gov (United States)

    Shahmoon, Ephraim; Leonhardt, Ulf

    2018-04-01

    One of the most intriguing manifestations of quantum zero-point fluctuations are the van der Waals and Casimir forces, often associated with vacuum fluctuations of the electromagnetic field. We study generalized fluctuation potentials acting on internal degrees of freedom of components in electrical circuits. These electronic Casimir-like potentials are induced by the zero-point current fluctuations of any general conductive circuit. For realistic examples of an electromechanical capacitor and a superconducting qubit, our results reveal the possibility of tunable forces between the capacitor plates, or the level shifts of the qubit, respectively. Our analysis suggests an alternative route toward the exploration of Casimir-like fluctuation potentials, namely, by characterizing and measuring them as a function of parameters of the environment. These tunable potentials may be useful for future nanoelectromechanical and quantum technologies.

  6. Particle Creation in Oscillating Cavities with Cubic and Cylindrical Geometry

    Science.gov (United States)

    Setare, M. R.; Dinani, H. T.

    2008-04-01

    In the present paper we study the creation of massless scalar particles from the quantum vacuum due to the dynamical Casimir effect by oscillating cavities with cubic and cylindrical geometry. To the first order of the amplitude we derive the expressions for the number of the created particles.

  7. Tunable electromechanical coupling of a carbon nanotube-reinforced variable cross-section nanoswitch with a piezoelectric effect

    International Nuclear Information System (INIS)

    Yang, W D; Li, Y D; Wang, X

    2016-01-01

    An analytical method is presented to investigate the pull-in instability of a carbon nanotube (CNT)-reinforced variable cross-section nanoswitch with a piezoelectric effect. Governing equations with variable coefficients are derived based on the nonlocal beam model with geometrical nonlinearity and are solved using the shooting method. All the nonlinear effects of the piezoelectric voltage, van der Waals force, Casimir force, CNT volume fraction, nonlocal parameters and width ratio on the pull-in instability are investigated. The pull-in electrostatic voltage increases with the increment of nonlocal parameters, which exhibits the significant scale-dependent behavior of nanostructures. The results show that the variable cross-section improves the flexural rigidity of the cantilever-type nanoswitch effectively, and that the piezoelectric effect of the piezoelectric layer is utilized to control the electrostatic force induced by the voltage exerted on the elastic layer, owing to piezoelectric materials’ advantages of rapid response, light weight and low energy consumption. (paper)

  8. Conference on the occasion of the 60th Birthday of Professor Emilio Elizalde

    CERN Document Server

    Odintsov, Sergey D; Xambó-Descamps, Sebastian; Cosmology, Quantum Vacuum and Zeta Functions

    2011-01-01

    Some major developments of physics in the last three decades are addressed by highly qualified specialists in different specific fields. They include renormalization problems in QFT, vacuum energy fluctuations and the Casimir effect in different configurations, and a wealth of applications. A number of closely related issues are also considered. The cosmological applications of these theories play a crucial role and are at the very heart of the book; in particular, the possibility to explain in a unified way the whole history of the evolution of the Universe: from primordial inflation to the present day accelerated expansion. Further, a description of the mathematical background underlying many of the physical theories considered above is provided. This includes the uses of zeta functions in physics, as in the regularization problems in QFT already mentioned, specifically in curved space-time, and in Casimir problems as.

  9. Impulsive moving mirror model and the stability of Schroedinger equation with impulse effect in a Banach space

    International Nuclear Information System (INIS)

    Kostadinov, S.I.; Petrov, G.

    1992-01-01

    From a special class of systems has been used a Schroedinger equation with impulse effect in Minkowski space field theory with time dependent boundary conditions, i.e. those of moving mirrors. The field theoretical approach for studying the properties of the vacuum starts from an analysis of the behaviour of local field quantities in Minkowski space with uniformly moving mirrors. For the impulsive moving mirror model is the real process of interaction between the quantum field and the external mirror a subject to disturbances in its evolution acting in time very short compared with the entire duration of the process. So the stability of the solution of the Schroedinger evolution equation for the process in the stability of the vacuum of Casimir. 8 refs

  10. Singular Poisson tensors

    International Nuclear Information System (INIS)

    Littlejohn, R.G.

    1982-01-01

    The Hamiltonian structures discovered by Morrison and Greene for various fluid equations were obtained by guessing a Hamiltonian and a suitable Poisson bracket formula, expressed in terms of noncanonical (but physical) coordinates. In general, such a procedure for obtaining a Hamiltonian system does not produce a Hamiltonian phase space in the usual sense (a symplectic manifold), but rather a family of symplectic manifolds. To state the matter in terms of a system with a finite number of degrees of freedom, the family of symplectic manifolds is parametrized by a set of Casimir functions, which are characterized by having vanishing Poisson brackets with all other functions. The number of independent Casimir functions is the corank of the Poisson tensor J/sup ij/, the components of which are the Poisson brackets of the coordinates among themselves. Thus, these Casimir functions exist only when the Poisson tensor is singular

  11. How complete is the classification of W-symmetries?

    International Nuclear Information System (INIS)

    Eholzer, W.; Honecker, A.; Huebel, R.

    1993-02-01

    In 2D conformal quantum field theory, we continue a systematic study of W-algebras with two and three generators and their highest weight representations focussing mainly of rational models. We review the known facts about rational models of W(2,σ)-algebras, in particular those models that are not related to some generically existing algebra. However, our new rational models of W-algebras with two generators all belong to one of the known series. The majority of W-algebras with three generators-including the new ones constructed in this letter- can be explained as subalgebras of Casimir algebras. Nonetheless, for one solution of W(2,4,6) we reveal some features that do not fit into the pattern of Casimir algebras or orbifolds thereof. This shows that even a classification of all Casimir algebras (or Toda field theories) will probably fail to classify all rational conformal field theories. (orig.)

  12. Automorphisms of W-algebras and extended rational conformal field theories

    International Nuclear Information System (INIS)

    Honecker, A.

    1992-11-01

    Many extended conformal algebras with one generator in addition to the Virasoro field as well as Casimir algebras have non-trivial outer automorphisms which enables one to impose 'twisted' boundary conditions on the chiral fields. We study their effect on the highest weight representations. We give formulae for the enlarged rational conformal field theories in both series of W-algebras with two generators and conjecture a general formula for the additional models in the minimal series of Casimir algebras. A third series of W-algebras with two generators which includes the spin three algebra at c = -2 also has finitely many additional fields in the twisted sector although the model itself is apparently not rational. The additional fields in the twisted sector have applications in statistical mechanics as we demonstrate for Z n -quantum spin chains with a particular type of boundary conditions. (orig.)

  13. Mathematical Structure in Quantum Systems and applications

    International Nuclear Information System (INIS)

    Cavero-Pelaez, I.; Clemente-Gallardo, J.; Marmo, G.; Muñoz--Castañeda, J.M.

    2013-01-01

    This volume contains most of the contributions presented at the Conference 'Mathematical Structures in Quantum Systems and applications', held at the Centro de Ciencias de Benasque 'Pedro Pascual', Benasque (Spain) from 8-14 July 2012. The aim of the Conference was to bring together physicists working on different applications of mathematical methods to quantum systems in order to enable the different communities to become acquainted with other approaches and techniques that could be used in their own fields of expertise. We concentrated on three main subjects: – the geometrical description of Quantum Mechanics; – the Casimir effect and its mathematical implications; – the Quantum Zeno Effect and Open system dynamics. Each of these topics had a set of general lectures, aimed at presenting a global view on the subject, and other more technical seminars. We would like to thank all participants for their contribution to creating a wonderful scientific atmosphere during the Conference. We would especially like to thank the speakers and the authors of the papers contained in this volume, the members of the Scientific Committee for their guidance and support and, of course, the referees for their generous work. Special thanks are also due to the staff of the Centro de Ciencias de Benasque 'Pedro Pascual' who made this successful meeting possible. On behalf of the organising committee and the authors we would also like to acknowledge the partial support provided by the ESF-CASIMIR network ('New Trends and Applications of the Casimir Effect'), the QUITEMAD research Project (“Quantum technologies at Madrid”, Ref. Comunidad de Madrid P2009/ESP-1594), the MICINN Project (MTM2011-16027-E) and the Government from Arag´on (DGA) (DGA, Department of Industry and Innovation and the European Social Fund, DGA-Grant 24/1) who made the Conference and this Proceedings volume possible.

  14. On a non-local gas dynamics like integrable hierarchy

    International Nuclear Information System (INIS)

    Brunelli, Jose Carlos; Das, Ashok

    2004-01-01

    We study a new hierarchy of equations derived from the system of isentropic gas dynamics equations where the pressure is a non-local function of the density. We show that the hierarchy of equations is integrable. We construct the two compatible Hamiltonian structures and show that the first structure has three distinct Casimirs while the second has one. The existence of Casimirs allows us to extend the flows to local ones. We construct an infinite series of commuting local Hamiltonians as well as three infinite series (related to the three Casimirs) of non-local charges. We discuss the zero curvature formulation of the system where we obtain a simple expression for the non-local conserved charges, which also clarifies the existence of the three series from a Lie algebraic point of view. We point out that the non-local hierarchy of Hunter-Zheng equations can be obtained from our non-local flows when the dynamical variables are properly constrained. (author)

  15. Towards measuring quantum electrodynamic torque with a levitated nanorod

    Science.gov (United States)

    Xu, Zhujing; Bang, Jaehoon; Ahn, Jonghoon; Hoang, Thai M.; Li, Tongcang

    2017-04-01

    According to quantum electrodynamics, quantum fluctuations of electromagnetic fields give rise to a zero-point energy that never vanishes, even in the absence of electromagnetic sources. The interaction energy will not only lead to the well-known Casimir force but will also contribute to the Casimir torque for anisotropic materials. We propose to use an optically levitated nanorod in vacuum and a birefringent substrate to experimentally investigate the QED torque. We have previously observed the libration of an optically levitated non-spherical nanoparticle in vacuum and found it to be an ultrasensitive torque sensor. A nanorod with a long axis of 300nm and a diameter of 60nm levitated in vacuum at 10 (- 8) torr will have a remarkable torque detection sensitivity on the order of 10 (- 28) Nm/ √Hz, which will be sufficient to detect the Casimir torque. This work is partially supported by the National Science Foundation under Grant No.1555035-PHY.

  16. Casimir effect for closed cavities with conducting and permeable walls

    International Nuclear Information System (INIS)

    Ferreira, L.A.; Zimerman, A.H.; Ruggiero, J.R.

    1980-01-01

    The quantum electromagnetic zero point energy is calculated for rectangular cavities where some of the walls are perfect conductors and the others are made of infinitely permeable materials. It is found that for cubic systems, for some configurations the zero point electromagnetic energy is positive, while in other configurations this zero point energy is negative. The consequences of these results on possible models for the electron are discussed. (Author) [pt

  17. New aspects of the casimir effect: Fluctuations and radiative reaction

    International Nuclear Information System (INIS)

    Barton, G.

    1994-01-01

    But since I am among equally irrational men, I won't be criticized I hope for the fact that there is no possible, practical reason for making these calculations....We all realize that no matter how small a thing is, if it has physical interest and is thought about carefully enough, your're bound to think of something that's good for something else. 48 refs

  18. Finite-temperature Casimir effect in the presence of nonlinear dielectrics

    DEFF Research Database (Denmark)

    Kheirandish, Fardin; Amooghorban, Ehsan; Soltani, Morteza

    2011-01-01

    Starting from a Lagrangian, the electromagnetic field in the presence of a nonlinear dielectric medium is quantized using path-integral techniques, and correlation functions of different fields are calculated. The susceptibilities of the nonlinear medium are obtained, and their relations to coupl......Starting from a Lagrangian, the electromagnetic field in the presence of a nonlinear dielectric medium is quantized using path-integral techniques, and correlation functions of different fields are calculated. The susceptibilities of the nonlinear medium are obtained, and their relations...

  19. Analytical and numerical verification of the Nernst theorem for metals

    International Nuclear Information System (INIS)

    Hoeye, Johan S.; Brevik, Iver; Ellingsen, Simen A.; Aarseth, Jan B.

    2007-01-01

    In view of the current discussion on the subject, an effort is made to show very accurately both analytically and numerically how the Drude dispersion model gives consistent results for the Casimir free energy at low temperatures. Specifically, for the free energy near T=0 we find the leading term proportional to T 2 and the next-to-leading term proportional to T 5-2 . These terms give rise to zero Casimir entropy as T→0 and are thus in accordance with Nernst's theorem

  20. No quantum friction between uniformly moving plates

    International Nuclear Information System (INIS)

    Philbin, T G; Leonhardt, U

    2009-01-01

    The Casimir forces between two plates moving parallel to each other at arbitrary constant speed are found by calculating the vacuum electromagnetic stress tensor. The perpendicular force between the plates is modified by the motion but there is no lateral force on the plates. Electromagnetic vacuum fluctuations do not therefore give rise to 'quantum friction' in this case, contrary to previous assertions. The result shows that the Casimir-Polder force on a particle moving at constant speed parallel to a plate also has no lateral component.

  1. Spontaneous symmetry breaking and neutral stability in the noncanonical Hamiltonian formalism

    International Nuclear Information System (INIS)

    Morrison, P.J.; Eliezer, S.

    1985-10-01

    The noncanonical Hamiltonian formalism is based upon a generalization of the Poisson bracket, a particular form of which is possessed by continuous media fields. Associated with this generalization are special constants of motion called Casimirs. These are constants that can be viewed as being built into the phase space, for they are invariant for all Hamiltonians. Casimirs are important because when added to the Hamiltonian they yield an effective Hamiltonian that produces equilibrium states upon variation. The stability of these states can be ascertained by a second variation. Goldstone's theorem, in its usual context, determines zero eigenvalues of the mass matrix for a given vacuum state, the equilibrium with minimum energy. Here, since for fluids and plasmas the vacuum state is uninteresting, we examine symmetry breaking for general equilibria. Broken symmetries imply directions of neutral stability. Two examples are presented: the nonlinear Alfven wave of plasma physics and the Korteweg-de Vries soliton. 46 refs

  2. Sugawara operators for classical Lie algebras

    CERN Document Server

    Molev, Alexander

    2018-01-01

    The celebrated Schur-Weyl duality gives rise to effective ways of constructing invariant polynomials on the classical Lie algebras. The emergence of the theory of quantum groups in the 1980s brought up special matrix techniques which allowed one to extend these constructions beyond polynomial invariants and produce new families of Casimir elements for finite-dimensional Lie algebras. Sugawara operators are analogs of Casimir elements for the affine Kac-Moody algebras. The goal of this book is to describe algebraic structures associated with the affine Lie algebras, including affine vertex algebras, Yangians, and classical \\mathcal{W}-algebras, which have numerous ties with many areas of mathematics and mathematical physics, including modular forms, conformal field theory, and soliton equations. An affine version of the matrix technique is developed and used to explain the elegant constructions of Sugawara operators, which appeared in the last decade. An affine analogue of the Harish-Chandra isomorphism connec...

  3. No quantum friction between uniformly moving plates

    Energy Technology Data Exchange (ETDEWEB)

    Philbin, T G; Leonhardt, U [School of Physics and Astronomy, University of St Andrews, North Haugh St Andrews, Fife KY16 9SS, Scotland (United Kingdom)], E-mail: tgp3@st-andrews.ac.uk

    2009-03-15

    The Casimir forces between two plates moving parallel to each other at arbitrary constant speed are found by calculating the vacuum electromagnetic stress tensor. The perpendicular force between the plates is modified by the motion but there is no lateral force on the plates. Electromagnetic vacuum fluctuations do not therefore give rise to 'quantum friction' in this case, contrary to previous assertions. The result shows that the Casimir-Polder force on a particle moving at constant speed parallel to a plate also has no lateral component.

  4. Rayleigh-Benard convection as a Nambu-metriplectic problem

    International Nuclear Information System (INIS)

    Bihlo, A

    2008-01-01

    The traditional Hamiltonian structure of the equations governing conservative Rayleigh-Benard convection (RBC) is singular, i.e., its Poisson bracket possesses nontrivial Casimir functionals. We show that a special form of one of these Casimirs can be used to extend the bilinear Poisson bracket to a trilinear generalized Nambu bracket. It is further shown that the equations governing dissipative RBC can be written as the superposition of the conservative Nambu bracket with a dissipative symmetric bracket. This leads to a Nambu-metriplectic system, which completes the geometrical picture of RBC. (fast track communication)

  5. Quantum and classical vacuum forces at zero and finite temperature; Quantentheoretische und klassische Vakuum-Kraefte bei Temperatur Null und bei endlicher Temperatur

    Energy Technology Data Exchange (ETDEWEB)

    Niekerken, Ole

    2009-06-15

    In this diploma thesis the Casimir-Polder force at zero temperature and at finite temperatures is calculated by using a well-defined quantum field theory (formulated in position space) and the method of image charges. For the calculations at finite temperature KMS-states are used. The so defined temperature describes the temperature of the electromagnetic background. A one oscillator model for inhomogeneous dispersive absorbing dielectric material is introduced and canonically quantized to calculate the Casimir-Polder force at a dielectric interface at finite temperature. The model fulfils causal commutation relations and the dielectric function of the model fulfils the Kramer-Kronig relations. We then use the same methods to calculate the van der Waals force between two neutral atoms at zero temperature and at finite temperatures. It is shown that the high temperature behaviour of the Casimir-Polder force and the van der Waals force are independent of {Dirac_h}. This means that they have to be understood classically, what is then shown in an algebraic statistical theory by using classical KMS states. (orig.)

  6. Quantum and classical vacuum forces at zero and finite temperature

    International Nuclear Information System (INIS)

    Niekerken, Ole

    2009-06-01

    In this diploma thesis the Casimir-Polder force at zero temperature and at finite temperatures is calculated by using a well-defined quantum field theory (formulated in position space) and the method of image charges. For the calculations at finite temperature KMS-states are used. The so defined temperature describes the temperature of the electromagnetic background. A one oscillator model for inhomogeneous dispersive absorbing dielectric material is introduced and canonically quantized to calculate the Casimir-Polder force at a dielectric interface at finite temperature. The model fulfils causal commutation relations and the dielectric function of the model fulfils the Kramer-Kronig relations. We then use the same methods to calculate the van der Waals force between two neutral atoms at zero temperature and at finite temperatures. It is shown that the high temperature behaviour of the Casimir-Polder force and the van der Waals force are independent of ℎ. This means that they have to be understood classically, what is then shown in an algebraic statistical theory by using classical KMS states. (orig.)

  7. Interaction of a charge with a thin plasma sheet

    International Nuclear Information System (INIS)

    Bordag, M.

    2007-01-01

    The interaction of the electromagnetic field with a two-dimensional plasma sheet intended to describe the pi-electrons of a carbon nanotube or a C 60 molecule is investigated. By first integrating out the displacement field of the plasma or the electromagnetic field, different representations for quantities like the Casimir energy are derived which are shown to be consistent with one another. Starting from the covariant gauge for the electromagnetic field, it is shown that the matching conditions to which the presence of the plasma sheet can be reduced are different from the commonly used ones. The difference in the treatments does not show up in the Casimir force between two parallel sheets, but it is present in the Casimir-Polder force between a charge or a neutral atom and a sheet. At once, since the plasma sheet is a regularization of the conductor boundary conditions, this sheds light on the difference in physics found earlier in the realization of conductor boundary conditions as 'thin' or 'thick' boundary conditions in Phys. Rev. D 70, 085010 (2004)

  8. The spin-orbit interaction and SU(3) generators in superdeformation

    Energy Technology Data Exchange (ETDEWEB)

    Sugawara-Tanabe, K [School of Social Information, Otsuma Women` s University, Tokyo (Japan); Arima, A [Tokyo Univ. (Japan). Dept. of Physics

    1992-08-01

    The authors found that the effect of spin-orbit coupling becomes smaller for the parity doublet level and for some other levels around superdeformation. This is because of the strongly deformed quadrupole field, which indicates the L-S coupling scheme is recovered for these levels. These levels can be described by an SU-3 group with eight generators and a Casimir operator. 6 refs., 3 figs.

  9. Cardy-Verlinde entropy formula in viscous cosmology

    International Nuclear Information System (INIS)

    Brevik, I.; Odintsov, S.D.

    2002-01-01

    The results of a paper by Verlinde (hep-th/0008140), discussing the holographic principle in a radiation dominated universe, are extended when allowing the cosmic fluid to possess a bulk viscosity. This corresponds to a nonconformally invariant theory. The generalization of the Cardy-Verlinde entropy formula to the case of a viscous universe seems from a formal point of view to be possible, although we question on physical grounds some elements of this kind of theory, especially the manner in which the Casimir energy is evaluated. Our discussion suggests that for nonconformally invariant theories the holographic definition of Casimir energy should be modified

  10. The energy–momentum tensor, the trace identity and the Casimir effect

    Indian Academy of Sciences (India)

    ˆΘµν is defined [1] in terms of the canonical energy-momentum tensor. ˆΘµν ... we shall first use standard methods in the sequel to check that the trace identity ... with a short Appendix that includes a derivation of some of the relevant equations ..... in (19), but after contraction with gαβ, remembering that the partial derivative.

  11. Finite temperature instability for compactification

    International Nuclear Information System (INIS)

    Accetta, F.S.; Kolb, E.W.

    1986-03-01

    We consider finite temperature effects upon theories with extra dimensions compactified via vacuum stress energy (Casimir) effects. For sufficiently high temperature, a static configuration for the internal space is impossible. At somewhat lower temperatures, there is an instability due to thermal fluctuations of radius of the compact dimensions. For both cases, the Universe can evolve to a de Sitter-like expansion of all dimensions. Stability to late times constrains the initial entropy of the universe. 28 refs., 1 fig., 2 tabs

  12. Research in theoretical particle physics

    International Nuclear Information System (INIS)

    McKay, D.W.; Munczek, H.; Ralston, J.

    1992-05-01

    This report discusses the following topics in high energy physics: dynamical symmetry breaking and Schwinger-Dyson equation; consistency bound on the minimal model Higgs mass; tests of physics beyond the standard model; particle astrophysics; the interface between perturbative and non-perturbative QCD; cosmology; anisotropy in quantum networks and integer quantum hall behavior; anomalous color transparency; quantum treatment of solitons; color transparency; quantum stabilization of skyrmions; and casimir effect

  13. Dark energy and the hierarchy problem

    International Nuclear Information System (INIS)

    Chen, Pisin

    2007-01-01

    The well-known hierarchy between the Planck scale (∼10 19 GeV) and the TeV scale, namely a ratio of ∼10 16 between the two, is coincidentally repeated in a inverted order between the TeV scale and the dark energy scale at ∼10 -3 eV implied by the observations. We argue that this is not a numerical coincidence. The same brane-world setups to address the first hierarchy problem may also in principle address this second hierarchy issue. Specifically, we consider supersymmetry in the bulk and its breaking on the brane and resort to the Casimir energy induced by the bulk graviton-gravitino mass-shift on the brane as the dark energy. For the ADD model we found that our notion is sensible only if the number of extra dimension n=2. We extend our study to the Randall-Sundrum model. Invoking the chirality-flip on the boundaries for SUSY-breaking, the zero-mode gravitino contribution to the Casimir energy does give rise to the double hierarchy. Unfortunately since the higher Kaluza-Klein modes acquire relative mass-shifts at the TeV level, the zero-mode contribution to Casimir energy is overshadowed

  14. What measurable zero point fluctuations can(not) tell us about dark energy

    International Nuclear Information System (INIS)

    Doran, M.

    2006-05-01

    We show that laboratory experiments cannot measure the absolute value of dark energy. All known experiments rely on electromagnetic interactions. They are thus insensitive to particles and fields that interact only weakly with ordinary matter. In addition, Josephson junction experiments only measure differences in vacuum energy similar to Casimir force measurements. Gravity, however, couples to the absolute value. Finally we note that Casimir force measurements have tested zero point fluctuations up to energies of ∝ 10 eV, well above the dark energy scale of ∝ 0.01 eV. Hence, the proposed cut-off in the fluctuation spectrum is ruled out experimentally. (Orig.)

  15. Photon density of states for deformed surfaces

    International Nuclear Information System (INIS)

    Emig, T

    2006-01-01

    A new approach to the Helmholtz spectrum for arbitrarily shaped boundaries and a rather general class of boundary conditions is introduced. We derive the boundary induced change of the density of states in terms of the free Green's function from which we obtain both perturbative and non-perturbative results for the Casimir interaction between deformed surfaces. As an example, we compute the lateral electrodynamic Casimir force between two corrugated surfaces over a wide parameter range. Universal behaviour, fixed only by the largest wavelength component of the surface shape, is identified at large surface separations. This complements known short distance expansions which are also reproduced

  16. Cardy-Verlinde Formula of Noncommutative Schwarzschild Black Hole

    Directory of Open Access Journals (Sweden)

    G. Abbas

    2014-01-01

    Full Text Available Few years ago, Setare (2006 has investigated the Cardy-Verlinde formula of noncommutative black hole obtained by noncommutativity of coordinates. In this paper, we apply the same procedure to a noncommutative black hole obtained by the coordinate coherent approach. The Cardy-Verlinde formula is entropy formula of conformal field theory in an arbitrary dimension. It relates the entropy of conformal field theory to its total energy and Casimir energy. In this paper, we have calculated the total energy and Casimir energy of noncommutative Schwarzschild black hole and have shown that entropy of noncommutative Schwarzschild black hole horizon can be expressed in terms of Cardy-Verlinde formula.

  17. Vacuum in the presence of electromagnetic fields and rotating boundaries

    International Nuclear Information System (INIS)

    Manogue, C.A.

    1984-01-01

    Two investigations of the properties of the vacuum are made. The first is a reconsideration of the classic Klein paradox, particle creation due to the presence of very strong external electromagnetic potentials. Expectation values of the current, momentum, and number operators, each of which is a measure of particle creation, are calculated for both massive spin zero and massive spin one half fields. The relationship between super-radiance and pair creation is explained. A review of past work by other authors is included and common conceptual errors are pointed out. The second investigation concerns the rotation of the vacuum caused by the rotation of boundaries. Just as the presence of boundaries can create a change in the vacuum expectation value of the energy density (the Casimir effect), the rotation of such boundaries can create changes in the vacuum expectation value of the momentum density. Calculations of the Casimir effect are made for a massless scalar field confined to an infinitely long square box. The change in the vacuum expectation value of the momentum density is calculated if this same box is rotating around its long central axis. In contrast, it is shown that for an infinitely long circular cylinder there is no change in the momentum density

  18. Equilibrium & Nonequilibrium Fluctuation Effects in Biopolymer Networks

    Science.gov (United States)

    Kachan, Devin Michael

    Fluctuation-induced interactions are an important organizing principle in a variety of soft matter systems. In this dissertation, I explore the role of both thermal and active fluctuations within cross-linked polymer networks. The systems I study are in large part inspired by the amazing physics found within the cytoskeleton of eukaryotic cells. I first predict and verify the existence of a thermal Casimir force between cross-linkers bound to a semi-flexible polymer. The calculation is complicated by the appearance of second order derivatives in the bending Hamiltonian for such polymers, which requires a careful evaluation of the the path integral formulation of the partition function in order to arrive at the physically correct continuum limit and properly address ultraviolet divergences. I find that cross linkers interact along a filament with an attractive logarithmic potential proportional to thermal energy. The proportionality constant depends on whether and how the cross linkers constrain the relative angle between the two filaments to which they are bound. The interaction has important implications for the synthesis of biopolymer bundles within cells. I model the cross-linkers as existing in two phases: bound to the bundle and free in solution. When the cross-linkers are bound, they behave as a one-dimensional gas of particles interacting with the Casimir force, while the free phase is a simple ideal gas. Demanding equilibrium between the two phases, I find a discontinuous transition between a sparsely and a densely bound bundle. This discontinuous condensation transition induced by the long-ranged nature of the Casimir interaction allows for a similarly abrupt structural transition in semiflexible filament networks between a low cross linker density isotropic phase and a higher cross link density bundle network. This work is supported by the results of finite element Brownian dynamics simulations of semiflexible filaments and transient cross-linkers. I

  19. Surface modes in physics

    CERN Document Server

    Sernelius, Bo E

    2011-01-01

    Electromagnetic surface modes are present at all surfaces and interfaces between material of different dielectric properties. These modes have very important effects on numerous physical quantities: adhesion, capillary force, step formation and crystal growth, the Casimir effect etc. They cause surface tension and wetting and they give rise to forces which are important e.g. for the stability of colloids.This book is a useful and elegant approach to the topic, showing how the concept of electromagnetic modes can be developed as a unifying theme for a range of condensed matter physics. The

  20. Autonomous quantum rotator

    DEFF Research Database (Denmark)

    Fogedby, Hans C.; Imparato, Alberto

    2018-01-01

    to a directed rotary motion. At variance with the classical case, the thermal fluctuations in the baths give rise to a non-vanishing average torque contribution; this is a genuine quantum effect akin to the Casimir effect. In the steady state the heat current flowing between the two baths is systematically......, the rotator cannot work either as a heat pump or as a heat engine. We finally use our exact results to extend an ab initio quantum simulation algorithm to the out-of-equilibrium regime. Copyright (C) EPLA, 2018...

  1. Quantum vacuum energy in graphs and billiards

    International Nuclear Information System (INIS)

    Kaplan, L.

    2010-01-01

    The vacuum (Casimir) energy in quantum field theory is a problem relevant both to new nanotechnology devices and to dark energy in cosmology. The crucial question is the dependence of the energy on the system geometry. Despite much progress since the first prediction of the Casimir effect in 1948 and its subsequent experimental verification in simple geometries, even the sign of the force in nontrivial situations is still a matter of controversy. Mathematically, vacuum energy fits squarely into the spectral theory of second-order self-adjoint elliptic linear differential operators. Specifically one promising approach is based on the small-t asymptotics of the cylinder kernel e -t√(H) , where H is the self-adjoint operator under study. In contrast with the well-studied heat kernel e -tH , the cylinder kernel depends in a non-local way on the geometry of the problem. We discuss some results by the Louisiana-Oklahoma-Texas collaboration on vacuum energy in model systems, including quantum graphs and two-dimensional cavities. The results may shed light on general questions, including the relationship between vacuum energy and periodic or closed classical orbits, and the contribution to vacuum energy of boundaries, edges, and corners.

  2. Spectral methods in quantum field theory

    International Nuclear Information System (INIS)

    Graham, Noah; Quandt, Markus; Weigel, Herbert

    2009-01-01

    This concise text introduces techniques from quantum mechanics, especially scattering theory, to compute the effects of an external background on a quantum field in general, and on the properties of the quantum vacuum in particular. This approach can be succesfully used in an increasingly large number of situations, ranging from the study of solitons in field theory and cosmology to the determination of Casimir forces in nano-technology. The method introduced and applied in this book is shown to give an unambiguous connection to perturbation theory, implementing standard renormalization conditions even for non-perturbative backgrounds. It both gives new theoretical insights, for example illuminating longstanding questions regarding Casimir stresses, and also provides an efficient analytic and numerical tool well suited to practical calculations. Last but not least, it elucidates in a concrete context many of the subtleties of quantum field theory, such as divergences, regularization and renormalization, by connecting them to more familiar results in quantum mechanics. While addressed primarily at young researchers entering the field and nonspecialist researchers with backgrounds in theoretical and mathematical physics, introductory chapters on the theoretical aspects of the method make the book self-contained and thus suitable for advanced graduate students. (orig.)

  3. Gap Dependent Bifurcation Behavior of a Nano-Beam Subjected to a Nonlinear Electrostatic Pressure

    Directory of Open Access Journals (Sweden)

    Mohammad Fathalilou

    Full Text Available This paper presents a study on the gap dependent bifurcation behavior of an electro statically-actuated nano-beam. The sizedependent behavior of the beam was taken into account by applying the couple stress theory. Two small and large gap distance regimes have been considered in which the intermolecular vdW and Casimir forces are dominant, respectively. It has been shown that changing the gap size can affect the fundamental frequency of the beam. The bifurcation diagrams for small gap distance revealed that by changing the gap size, the number and type of the fixed points can change. However, for large gap regime, where the Casimir force is the dominant intermolecular force, changing the gap size does not affect the quality of the bifurcation behavior.

  4. Principles and applications of nanomems physics

    CERN Document Server

    Santos, Hector

    2005-01-01

    ""Principles and Applications of NanoMEMS Physics"" presents the first unified exposition of the physical principles at the heart of NanoMEMS-based devices and applications. In particular, after beginning with a comprehensive presentation of the fundamentals and limitations of nanotechnology and MEMS fabrication techniques, the book addresses the physics germane to this dimensional regime, namely, quantum wave-particle phenomena, including, the manifestation of charge discreteness, quantized electrostatic actuation, and the Casimir effect, and quantum wave phenomena, including, quantized elect

  5. Quantum creation of the universe in N = 8 supergravity

    International Nuclear Information System (INIS)

    Goncharov, Yu.P.; Bytsenko, A.A.

    1988-01-01

    We discuss the possibility of quantum creation of an inflationary universe filled with the fields of maximal extended N = 8 supergravity. If the created universe has spatial topology (S 1 ) 3 and after the creation Starobinskii's inflationary scenario through the topological Casimir effect in N = 8 supergravity is realized, the probability of creation of such a universe can be estimated in the semiclassical approximation. The estimate shows that the creation of a universe with a more isotropic topology is more probable

  6. Eternal and evanescent black holes and accelerating mirror analogs

    Science.gov (United States)

    Good, Michael R. R.; Linder, Eric V.

    2018-03-01

    The analogy between black hole radiation and accelerating mirror radiation (the dynamical Casimir effect) is particularly strong for mirror trajectories giving rise to a constant thermal flux of particles. We present new ways to achieve such thermal plateaus, and customize their finite, semi-infinite, and eternal presence, corresponding to forming/collapsing, complete-evaporation/remnants, and eternal black holes. We find simple expressions for the energy flux in terms of the mirror rapidity as a function of proper time and null time.

  7. 77 FR 63707 - General Pulaski Memorial Day, 2012

    Science.gov (United States)

    2012-10-16

    ... men from Europe and America alike, Brigadier General Casimir Pulaski battled to extend the principles... standing proudly with its strong ally, a free and independent Poland. On General Pulaski Memorial Day, we...

  8. Q-creation and annihilation tensors for the two parameters deformation of U(SU(2))

    International Nuclear Information System (INIS)

    Wehrhahn, R.F.; Vraceanu, D.

    1993-03-01

    The Jordan-Schwinger construction for the Hopf algebra U qp (su(2)) is realized. The creation and annihilation tensor operators together with their tensor products including the Casimir operators are calculated. (orig.)

  9. Surface dependency in thermodynamics of ideal gases

    International Nuclear Information System (INIS)

    Sisman, Altug

    2004-01-01

    The Casimir-like size effect rises in ideal gases confined in a finite domain due to the wave character of atoms. By considering this effect, thermodynamic properties of an ideal gas confined in spherical and cylindrical geometries are derived and compared with those in rectangular geometry. It is seen that an ideal gas exhibits an unavoidable quantum surface free energy and surface over volume ratio becomes a control variable on thermodynamic state functions in microscale. Thermodynamics turns into non-extensive thermodynamics and geometry difference becomes a driving force since the surface over volume ratio depends on the geometry

  10. Quantum levitation of nanoparticles seen with ultracold neutrons

    Energy Technology Data Exchange (ETDEWEB)

    Nesvizhevsky, V. V., E-mail: nesvizhevsky@ill.eu [Institut Laue-Langevin (France); Voronin, A. Yu. [Lebedev Institute (Russian Federation); Lambrecht, A.; Reynaud, S. [Laboratoire Kastler-Brossel, CNRS, ENS, UPMC (France); Lychagin, E. V.; Muzychka, A. Yu.; Strelkov, A. V. [Joint Institute for Nuclear Research (Russian Federation)

    2013-09-15

    Analyzing new experiments with ultracold neutrons (UCNs) we show that physical adsorption of nanoparticles/nanodroplets, levitating in high-excited states in a deep and broad potential well formed by van der Waals/Casimir-Polder (vdW/CP) forces results in new effects on a cross-road of the fields of fundamental interactions, neutron, surface and nanoparticle physics. Accounting for the interaction of UCNs with nanoparticles explains a recently discovered intriguing so-called 'small heating' of UCNs in traps. It might be relevant to the striking conflict of the neutron lifetime experiments with smallest reported uncertainties by adding false effects there.

  11. Quantum levitation of nanoparticles seen with ultracold neutrons

    International Nuclear Information System (INIS)

    Nesvizhevsky, V. V.; Voronin, A. Yu.; Lambrecht, A.; Reynaud, S.; Lychagin, E. V.; Muzychka, A. Yu.; Strelkov, A. V.

    2013-01-01

    Analyzing new experiments with ultracold neutrons (UCNs) we show that physical adsorption of nanoparticles/nanodroplets, levitating in high-excited states in a deep and broad potential well formed by van der Waals/Casimir-Polder (vdW/CP) forces results in new effects on a cross-road of the fields of fundamental interactions, neutron, surface and nanoparticle physics. Accounting for the interaction of UCNs with nanoparticles explains a recently discovered intriguing so-called “small heating” of UCNs in traps. It might be relevant to the striking conflict of the neutron lifetime experiments with smallest reported uncertainties by adding false effects there

  12. Maximal Fluctuations of Confined Actomyosin Gels: Dynamics of the Cell Nucleus.

    Science.gov (United States)

    Rupprecht, J-F; Singh Vishen, A; Shivashankar, G V; Rao, M; Prost, J

    2018-03-02

    We investigate the effect of stress fluctuations on the stochastic dynamics of an inclusion embedded in a viscous gel. We show that, in nonequilibrium systems, stress fluctuations give rise to an effective attraction towards the boundaries of the confining domain, which is reminiscent of an active Casimir effect. We apply this generic result to the dynamics of deformations of the cell nucleus, and we demonstrate the appearance of a fluctuation maximum at a critical level of activity, in agreement with recent experiments [E. Makhija, D. S. Jokhun, and G. V. Shivashankar, Proc. Natl. Acad. Sci. U.S.A. 113, E32 (2016)PNASA60027-842410.1073/pnas.1513189113].

  13. Dispersive force between dissimilar materials: Geometrical effects

    International Nuclear Information System (INIS)

    Noguez, Cecilia; Roman-Velazquez, C.E.

    2004-01-01

    We calculate the Casimir force or dispersive van der Waals force between a spherical nanoparticle and a planar substrate, both with arbitrary dielectric properties. We show that the force between the sphere and half-space can be calculated through the interacting surface plasmons of the bodies. Using a Spectral Representation formalism, we show that the force of a sphere made of a material A and a half-space made of a material B differs from the case when the sphere is made of B, and the half-space is made of A. We find that the difference depends on the plasma frequency of the materials, the geometry, and the distance of separation between the sphere and half-space. The differences show the importance of the geometry, and make evident the necessity of realistic descriptions of the system beyond the Derjaguin Approximation or Proximity Theorem Approximation

  14. Pull-in instability of paddle-type and double-sided NEMS sensors under the accelerating force

    Science.gov (United States)

    Keivani, M.; Khorsandi, J.; Mokhtari, J.; Kanani, A.; Abadian, N.; Abadyan, M.

    2016-02-01

    Paddle-type and double-sided nanostructures are potential for use as accelerometers in flying vehicles and aerospace applications. Herein the pull-in instability of the cantilever paddle-type and double-sided sensors in the Casimir regime are investigated under the acceleration. The D'Alembert principle is employed to transform the accelerating system into an equivalent static system by incorporating the accelerating force. Based on the couple stress theory (CST), the size-dependent constitutive equations of the sensors are derived. The governing nonlinear equations are solved by two approaches, i.e. modified variational iteration method and finite difference method. The influences of the Casimir force, geometrical parameters, acceleration and the size phenomenon on the instability performance have been demonstrated. The obtained results are beneficial to design and fabricate paddle-type and double-sided accelerometers.

  15. 2190-IJBCS-Article-Casimir Anouma

    African Journals Online (AJOL)

    hp

    evaluation test indicated a significant difference (p<0.05) between the placali .... with a knife and cut into large longitudinal .... If necessary, Tukey HSD multiple ..... physicochemical characteristics of yace fermented flours. Error source. Test.

  16. Cardy-Verlinde Formula and Its Self-Gravitational Corrections for Regular Black Holes

    International Nuclear Information System (INIS)

    Saleem, Rabia; Sharif, M.

    2014-01-01

    We check the consistency of the entropy of Bardeen and Ayón Beato-García-Bronnikov black holes with the entropy of particular conformal field theory via Cardy-Verlinde formula. We also compute the first-order semiclassical corrections of this formula due to self-gravitational effects by modifying pure extensive and Casimir energy in the context of Keski-Vakkuri, Kraus and Wilczek analysis. It is concluded that the correction term remains positive for both black holes, which leads to the violation of the holographic bound

  17. Aspects of quantum field theory in curved space-time

    International Nuclear Information System (INIS)

    Fulling, S.A.

    1989-01-01

    The theory of quantum fields on curved spacetimes has attracted great attention since the discovery, by Stephen Hawking, of black-hole evaporation. It remains an important subject for the understanding of such contemporary topics as inflationary cosmology, quantum gravity and superstring theory. The topics covered include normal-mode expansions for a general elliptic operator, Fock space, the Casimir effect, the Klein 'paradox', particle definition and particle creation in expanding universes, asymptotic expansion of Green's functions and heat kernels, and renormalization of the stress tensor. (author)

  18. Basal electric and magnetic fields of celestial bodies come from positive-negative charge separation caused by gravitation of quasi-Casimir pressure in weak interaction

    Science.gov (United States)

    Chen, Shao-Guang

    According to f =d(mv)/dt=m(dv/dt)+ v(dm/dt), a same gravitational formula had been de-duced from the variance in physical mass of QFT and from the variance in mass of inductive energy-transfer of GR respectively: f QF T = f GR = -G (mM/r2 )((r/r)+(v/c)) when their interaction-constants are all taken the experimental values (H05-0029-08, E15-0039-08). f QF T is the quasi-Casimir pressure. f GR is equivalent to Einstein's equation, then more easy to solve it. The hypothesis of the equivalent principle is not used in f QF T , but required by f GR . The predictions of f QF T and f GR are identical except that f QF T has quantum effects but f GR has not and f GR has Lense-Thirring effect but f QF T has not. The quantum effects of gravitation had been verified by Nesvizhevsky et al with the ultracold neutrons falling in the earth's gravitational field in 2002. Yet Lense-Thirring effect had not been measured by GP-B. It shows that f QF T is essential but f GR is phenomenological. The macro-f QF T is the statistic average pressure collided by net virtual neutrinos ν 0 flux (after self-offset in opposite directions) and in direct proportion to the mass. But micro-f QF T is in direct proportion to the scattering section. The electric mass (in inverse proportion to de Broglie wavelength λ) far less than nucleonic mass and the electric scattering section (in direct proportion to λ2 ) far large than that of nucleon, then the net ν 0 flux pressure exerted to electron far large than that to nucleon and the electric displacement far large than that of nucleon, it causes the gravitational polarization of positive-negative charge center separation. Because the gravity far less than the electromagnetic binding force, in atoms the gravitational polarization only produces a little separation. But the net ν 0 flux can press a part freedom electrons in plasma of ionosphere into the earth's surface, the static electric force of redundant positive ions prevents electrons from further

  19. New interpretation of matter-antimatter asymmetry based on branes and possible observational consequences

    International Nuclear Information System (INIS)

    Cai Ronggen; Li Tong; Li Xueqian; Wang Xun

    2007-01-01

    Motivated by the alpha-magnetic-spectrometer (AMS) project, we assume that after the big bang or inflation epoch, antimatter was repelled onto one brane which is separated from our brane where all the observational matter resides. It is suggested that CP may be spontaneously broken, the two branes would correspond to ground states for matter and antimatter, respectively. Generally a complex scalar field which is responsible for the spontaneous CP violation, exists in the space between the branes. The matter and antimatter on the two branes attract each other via gravitational force, meanwhile the scalar field causes a Casimir effect to result in a repulsive force against the gravitation. We find that the Casimir force is much stronger than the gravitational force, as long as the separation of the two branes is small. Thus at early epoch after the big bang, the two branes were closer and then have been separated by the Casimir repulsive force from each other. The trend will continue until the separation is sufficiently large and then the gravitational force observed in our four-space would obviously deviate from the Newton's universal gravitational law. We suppose that there is a potential barrier at the brane boundary, which is similar to the surface tension for a water membrane. The barrier prevents the matter (antimatter) particles from entering the space between two branes and jump from one brane to another. However, by the quantum tunneling, a sizable antimatter flux may come to our brane and be observed by the AMS. In this work by considering two possible models, i.e. the naive flat space-time and Randall-Sundrum models, and using the observational data on the visible matter in our universe as inputs, we derive the antimatter flux which comes to our detector in the nonrelativistic approximation and make a rough numerical estimate of possible numbers of antihelium at AMS

  20. Nonlinear stability of ideal fluid equilibria

    International Nuclear Information System (INIS)

    Holm, D.D.

    1988-01-01

    The Lyapunov method for establishing stability is related to well- known energy principles for nondissipative dynamical systems. A development of the Lyapunov method for Hamiltonian systems due to Arnold establishes sufficient conditions for Lyapunov stability by using the energy plus other conserved quantities, together with second variations and convexity estimates. When treating the stability of ideal fluid dynamics within the Hamiltonian framework, a useful class of these conserved quantities consists of the Casimir functionals, which Poisson-commute with all functionals of the dynamical fluid variables. Such conserved quantities, when added to the energy, help to provide convexity estimates that bound the growth of perturbations. These convexity estimates, in turn, provide norms necessary for establishing Lyapunov stability under the nonlinear evolution. In contrast, the commonly used second variation or spectral stability arguments only prove linearized stability. As ideal fluid examples, in these lectures we discuss planar barotropic compressible fluid dynamics, the three-dimensional hydrostatic Boussinesq model, and a new set of shallow water equations with nonlinear dispersion due to Basdenkov, Morosov, and Pogutse[1985]. Remarkably, all three of these samples have the same Hamiltonian structure and, thus, possess the same Casimir functionals upon which their stability analyses are based. We also treat stability of modified quasigeostrophic flow, a problem whose Hamiltonian structure and Casimirs closely resemble Arnold's original example. Finally, we discuss some aspects of conditional stability and the applicability of Arnold's development of the Lyapunov technique. 100 refs

  1. Indexes to Volume 56

    Indian Academy of Sciences (India)

    The gravitational wave symphony of the Universe. B S Sathyaprakash ... A verification of quantum field theory – measurement of Casimir force. Anushree Roy and U ... stability in the presence of parallel electric field. Harsha Jalori and A K ...

  2. Aspects of quantum field theory in curved space-time

    Energy Technology Data Exchange (ETDEWEB)

    Fulling, S.A. (Texas A and M Univ., College Station, TX (USA). Dept. of Mathematics)

    1989-01-01

    The theory of quantum fields on curved spacetimes has attracted great attention since the discovery, by Stephen Hawking, of black-hole evaporation. It remains an important subject for the understanding of such contemporary topics as inflationary cosmology, quantum gravity and superstring theory. The topics covered include normal-mode expansions for a general elliptic operator, Fock space, the Casimir effect, the Klein 'paradox', particle definition and particle creation in expanding universes, asymptotic expansion of Green's functions and heat kernels, and renormalization of the stress tensor. (author).

  3. Heavy fermion stabilization of solitons in 1+1 dimensions

    International Nuclear Information System (INIS)

    Farhi, E.; Graham, N.; Jaffe, R.L.; Weigel, H.

    2000-01-01

    We find static solitons stabilized by quantum corrections in a (1+1) -dimensional model with a scalar field chirally coupled to fermions. This model does not support classical solitons. We compute the renormalized energy functional including one-loop quantum corrections. We carry out a variational search for a configuration that minimizes the energy functional. We find a nontrivial configuration with fermion number whose energy is lower than the same number of free fermions quantized about the translationally invariant vacuum. In order to compute the quantum corrections for a given background field we use a phase-shift parameterization of the Casimir energy. We identify orders of the Born series for the phase shift with perturbative Feynman diagrams in order to renormalize the Casimir energy using perturbatively determined counterterms. Generalizing dimensional regularization, we demonstrate that this procedure yields a finite and unambiguous energy functional

  4. The Polyakov loop and its correlators in higher representations of SU(3) at finite temperature

    International Nuclear Information System (INIS)

    Huebner, K.A.

    2006-09-01

    We have calculated the Polyakov loop in representations D=3,6,8,10,15,15',24,27 and diquark and baryonic Polyakov loop correlation functions with fundamental sources in SU(3) pure gauge theory and 2-flavour QCD with staggered quarks and Q anti Q-singlet correlation functions with sources in the fundamental and adjoint representation in SU(3) pure gauge theory. We have tested a new renormalisation procedure for the Polyakov loop and extracted the adjoint Polyakov loop below T c , binding energy of the gluelump and string breaking distances. Moreover, we could show Casimir scaling for the Polyakov loop in different representations in SU(3) pure gauge theory above T c . Diquark antitriplet and baryonic singlet free energies are related to the Q anti Q-singlet free energies by the Casimir as well. (orig.)

  5. The Polyakov loop and its correlators in higher representations of SU(3) at finite temperature

    Energy Technology Data Exchange (ETDEWEB)

    Huebner, K.A.

    2006-09-15

    We have calculated the Polyakov loop in representations D=3,6,8,10,15,15',24,27 and diquark and baryonic Polyakov loop correlation functions with fundamental sources in SU(3) pure gauge theory and 2-flavour QCD with staggered quarks and Q anti Q-singlet correlation functions with sources in the fundamental and adjoint representation in SU(3) pure gauge theory. We have tested a new renormalisation procedure for the Polyakov loop and extracted the adjoint Polyakov loop below T{sub c}, binding energy of the gluelump and string breaking distances. Moreover, we could show Casimir scaling for the Polyakov loop in different representations in SU(3) pure gauge theory above T{sub c}. Diquark antitriplet and baryonic singlet free energies are related to the Q anti Q-singlet free energies by the Casimir as well. (orig.)

  6. The localized quantum vacuum field

    International Nuclear Information System (INIS)

    Dragoman, D

    2008-01-01

    A model for the localized quantum vacuum is proposed in which the zero-point energy (ZPE) of the quantum electromagnetic field originates in energy- and momentum-conserving transitions of material systems from their ground state to an unstable state with negative energy. These transitions are accompanied by emissions and re-absorptions of real photons, which generate a localized quantum vacuum in the neighborhood of material systems. The model could help resolve the cosmological paradox associated with the ZPE of electromagnetic fields, while reclaiming quantum effects associated with quantum vacuum such as the Casimir effect and the Lamb shift. It also offers a new insight into the Zitterbewegung of material particles

  7. The localized quantum vacuum field

    Energy Technology Data Exchange (ETDEWEB)

    Dragoman, D [Physics Department, University of Bucharest, PO Box MG-11, 077125 Bucharest (Romania)], E-mail: danieladragoman@yahoo.com

    2008-03-15

    A model for the localized quantum vacuum is proposed in which the zero-point energy (ZPE) of the quantum electromagnetic field originates in energy- and momentum-conserving transitions of material systems from their ground state to an unstable state with negative energy. These transitions are accompanied by emissions and re-absorptions of real photons, which generate a localized quantum vacuum in the neighborhood of material systems. The model could help resolve the cosmological paradox associated with the ZPE of electromagnetic fields, while reclaiming quantum effects associated with quantum vacuum such as the Casimir effect and the Lamb shift. It also offers a new insight into the Zitterbewegung of material particles.

  8. Properties of the stress tensor in more than two dimensions

    International Nuclear Information System (INIS)

    Cappelli, A.

    1988-03-01

    Some aspects of conformal invariance in more than two dimensions are analysed. In this case conformal (Weyl) transformations of the metric are not realized in general by coordinate transformations. The operator product expansion of the stress tensor is investigated by means of examples in the free bosonic and fermionic theories. The effective action for the general form of the trace anomaly is built in four dimensions and the Wess-Zumino consistency conditions are discussed. This gives the anomalous transformation law of the stress tensor and the relation to the Casimir effect in the geometry R x S 3 . The explicit computation of the bosonic partition function provides a check

  9. PREFACE: Quantum Field Theory Under the Influence of External Conditions (QFEXT07)

    Science.gov (United States)

    Bordag, M.; Mostepanenko, V. M.

    2008-04-01

    This special issue contains papers reflecting talks presented at the 8th Workshop on Quantum Field Theory Under the Influence of External Conditions (QFEXT07), held on 17 21 September 2007, at Leipzig University. This workshop gathered 108 physicists and mathematicians working on problems which are focused on the following topics: •Casimir and van der Waals forces—progress in theory and new experiments, applications at micro- and nano-scale •Casimir effect—exact results, approximate methods and mathematical problems •Vacuum quantum effects in classical background fields—renormalization issues, singular backgrounds, applications to particle and high energy physics •Vacuum energy and gravity, vacuum energy in supersymmetric and noncommutative theories. This workshop is part of a series started in 1989 and 1992 in Leipzig by Dieter Robaschik, and continued in 1995, 1998 and 2001 in Leipzig by Michael Bordag. In 2003 this Workshop was organized by Kimball A Milton in Oklahoma, in 2005 by Emilio Elizalde in Barcelona and in 2007 it returned to Leipzig. The field of physics after which this series of workshops is named is remarkably broad. It stretches from experimental work on the measurement of dispersion forces between macroscopic bodies to quantum corrections in the presence of classical background fields. The underlying physical idea is that even in its ground state (vacuum) a quantum system responds to changes in its environment. The universality of this idea makes the field of its application so very broad. The most prominent manifestation of vacuum energy is the Casimir effect. This is, in its original formulation, the attraction between conducting planes due to the vacuum fluctuations of the electromagnetic field. In a sense, this is the long-range tail of the more general dispersion forces acting between macroscopic bodies. With the progress in nanotechnology, dispersion forces become of direct practical significance. On a more theoretical side

  10. Invariants and labels for Lie-Poisson Systems

    International Nuclear Information System (INIS)

    Thiffeault, J.L.; Morrison, P.J.

    1998-04-01

    Reduction is a process that uses symmetry to lower the order of a Hamiltonian system. The new variables in the reduced picture are often not canonical: there are no clear variables representing positions and momenta, and the Poisson bracket obtained is not of the canonical type. Specifically, we give two examples that give rise to brackets of the noncanonical Lie-Poisson form: the rigid body and the two-dimensional ideal fluid. From these simple cases, we then use the semidirect product extension of algebras to describe more complex physical systems. The Casimir invariants in these systems are examined, and some are shown to be linked to the recovery of information about the configuration of the system. We discuss a case in which the extension is not a semidirect product, namely compressible reduced MHD, and find for this case that the Casimir invariants lend partial information about the configuration of the system

  11. Micro-/nanoscaled irreversible Otto engine cycle with friction loss and boundary effects and its performance characteristics

    International Nuclear Information System (INIS)

    Nie, Wenjie; Liao, Qinghong; Zhang, ChunQiang; He, Jizhou

    2010-01-01

    An irreversible cycle model of the micro-/nanoscaled Otto engine cycle with internal friction loss is established. The general expressions of the work output and efficiency of the cycle are calculated based on the finite system thermodynamic theory, in which the quantum boundary effect of gas particles as working substance and the mechanical Casimir effect of gas system are considered. It is found that, for a micro-/nanoscaled Otto cycle devices, the work output W and efficiency η of the cycle can be expressed as the functions of the temperature ratio τ of the two heat reservoirs, the volume ratio r V and the surface area ratio r A of the two isochoric processes, the dimensionless thermal wavelength λ and other parameters of cycle, while for a macroscaled Otto cycle devices, the work output W 0 and efficiency η 0 of the cycle are independent of the surface area ratio r A and the dimensionless thermal wavelength λ. Further, the influence of boundary of cycle on the performance characteristics of the micro-/nanoscaled Otto cycle are analyzed in detail by introducing the output ratio W/W 0 and efficiency ratio η/η 0 . The results present the general performance characteristics of a micro-/nanoscaled Otto cycle and may serve as the basis for the design of a realistic Otto cycle device in micro-/nanoscale.

  12. Influence of random roughness on the adhesion between metal surfaces due to capillary condensation

    NARCIS (Netherlands)

    van Zwol, P. J.; Palasantzas, G.; De Hosson, J. Th. M.

    2007-01-01

    The capillary force was measured by atomic force microscopy between a gold coated sphere mounted on a cantilever and gold surfaces with different roughnesses. For smooth surfaces the capillary adhesive force surpasses in magnitude any dispersion, e.g., van der Waals/Casimir and/or electrostatic

  13. Is the Free Vacuum Energy Infinite?

    International Nuclear Information System (INIS)

    Shirazi, S. M.; Razmi, H.

    2015-01-01

    Considering the fundamental cutoff applied by the uncertainty relations’ limit on virtual particles’ frequency in the quantum vacuum, it is shown that the vacuum energy density is proportional to the inverse of the fourth power of the dimensional distance of the space under consideration and thus the corresponding vacuum energy automatically regularized to zero value for an infinitely large free space. This can be used in regularizing a number of unwanted infinities that happen in the Casimir effect, the cosmological constant problem, and so on without using already known mathematical (not so reasonable) techniques and tricks

  14. Alpenglow. A signature for chameleons in axion-like particle search experiments

    International Nuclear Information System (INIS)

    Ahlers, M.; Lindner, A.; Ringwald, A.; Schrempp, L.; Weniger, C.

    2007-10-01

    We point out that chameleon field theories might reveal themselves as an ''afterglow'' effect in axion-like particle search experiments due to chameleon-photon conversion in a magnetic field. We estimate the parameter space which is accessible by currently available technology and find that afterglow experiments could constrain this parameter space in a way complementary to gravitational and Casimir force experiments.In addition, one could reach photon-chameleon couplings which are beyond the sensitivity of common laser polarization experiments. We also sketch the idea of a Fabry-Perot cavity with chameleons which could increase the experimental sensitivity significantly. (orig.)

  15. Remark on the computation of mode sums

    International Nuclear Information System (INIS)

    Allen, Theodore J.; Olsson, M. G.; Schmidt, Jeffrey R.

    2000-01-01

    The computation of mode sums of the types encountered in basic quantum field theoretic applications is addressed with an emphasis on their expansions into functions of distance that can be interpreted as potentials. We show how to regularize and calculate the Casimir energy for the continuum Nambu-Goto string with massive ends as well as for the discrete Isgur-Paton non-relativistic string with massive ends. As an additional example, we examine the effect on the interquark potential of a constant Kalb-Ramond field strength interacting with a QCD string. (c) 2000 The American Physical Society

  16. Alpenglow: A signature for chameleons in axionlike particle search experiments

    International Nuclear Information System (INIS)

    Ahlers, M.; Lindner, A.; Ringwald, A.; Schrempp, L.; Weniger, C.

    2008-01-01

    We point out that chameleon field theories might reveal themselves as an afterglow effect in axionlike particle search experiments due to chameleon-photon conversion in a magnetic field. We estimate the parameter space which is accessible by currently available technology and find that afterglow experiments could constrain this parameter space in a way complementary to gravitational and Casimir force experiments. In addition, one could reach photon-chameleon couplings which are beyond the sensitivity of common laser polarization experiments. We also sketch the idea of a Fabry-Perot cavity with chameleons which could increase the experimental sensitivity significantly

  17. Alpenglow. A signature for chameleons in axion-like particle search experiments

    Energy Technology Data Exchange (ETDEWEB)

    Ahlers, M.; Lindner, A.; Ringwald, A.; Schrempp, L.; Weniger, C.

    2007-10-15

    We point out that chameleon field theories might reveal themselves as an ''afterglow'' effect in axion-like particle search experiments due to chameleon-photon conversion in a magnetic field. We estimate the parameter space which is accessible by currently available technology and find that afterglow experiments could constrain this parameter space in a way complementary to gravitational and Casimir force experiments.In addition, one could reach photon-chameleon couplings which are beyond the sensitivity of common laser polarization experiments. We also sketch the idea of a Fabry-Perot cavity with chameleons which could increase the experimental sensitivity significantly. (orig.)

  18. Non-equilibrium concentration fluctuations in binary liquids with realistic boundary conditions.

    Science.gov (United States)

    Ortiz de Zárate, J M; Kirkpatrick, T R; Sengers, J V

    2015-09-01

    Because of the spatially long-ranged nature of spontaneous fluctuations in thermal non-equilibrium systems, they are affected by boundary conditions for the fluctuating hydrodynamic variables. In this paper we consider a liquid mixture between two rigid and impervious plates with a stationary concentration gradient resulting from a temperature gradient through the Soret effect. For liquid mixtures with large Lewis and Schmidt numbers, we are able to obtain explicit analytical expressions for the intensity of the non-equilibrium concentration fluctuations as a function of the frequency ω and the wave number q of the fluctuations. In addition we elucidate the spatial dependence of the intensity of the non-equilibrium fluctuations responsible for a non-equilibrium Casimir effect.

  19. Extended inflation from higher-dimensional theories

    International Nuclear Information System (INIS)

    Holman, R.; Kolb, E.W.; Vadas, S.L.; Wang, Y.

    1991-01-01

    We consider the possibility that higher-dimensional theories may, upon reduction to four dimensions, allow extended inflation to occur. We analyze two separate models. One is a very simple toy model consisting of higher-dimensional gravity coupled to a scalar field whose potential allows for a first-order phase transition. The other is a more sophisticated model incorporating the effects of nontrivial field configurations (monopole, Casimir, and fermion bilinear condensate effects) that yield a nontrivial potential for the radius of the internal space. We find that extended inflation does not occur in these models. We also find that the bubble nucleation rate in these theories is time dependent unlike the case in the original version of extended inflation

  20. Quantum electrodynamical torques in the presence of Brownian motion

    NARCIS (Netherlands)

    Munday, J. N.; Iannuzzi, D.; Capasso, F.

    2006-01-01

    Quantum fluctuations of the electromagnetic field give rise to a zero-point energy that persists even in the absence of electromagnetic sources. One striking consequence of the zero-point energy is manifested in the Casimir force, which causes two electrically neutral metallic plates to attract in

  1. Critical Casimir forces and anomalous wetting

    Indian Academy of Sciences (India)

    (3) With Dirichlet boundary conditions, the critical temperature in the film is sig- ... studies: new experiments should identify the origin of the L-dependence, and ... and complete wetting should occur as T approaches Tt. The above argument is ...

  2. Classification and identification of Lie algebras

    CERN Document Server

    Snobl, Libor

    2014-01-01

    The purpose of this book is to serve as a tool for researchers and practitioners who apply Lie algebras and Lie groups to solve problems arising in science and engineering. The authors address the problem of expressing a Lie algebra obtained in some arbitrary basis in a more suitable basis in which all essential features of the Lie algebra are directly visible. This includes algorithms accomplishing decomposition into a direct sum, identification of the radical and the Levi decomposition, and the computation of the nilradical and of the Casimir invariants. Examples are given for each algorithm. For low-dimensional Lie algebras this makes it possible to identify the given Lie algebra completely. The authors provide a representative list of all Lie algebras of dimension less or equal to 6 together with their important properties, including their Casimir invariants. The list is ordered in a way to make identification easy, using only basis independent properties of the Lie algebras. They also describe certain cl...

  3. Enhanced symmetries of gauge theory and resolving the spectrum of local operators

    International Nuclear Information System (INIS)

    Kimura, Yusuke; Ramgoolam, Sanjaye

    2008-01-01

    Enhanced global non-Abelian symmetries at zero coupling in Yang Mills theory play an important role in diagonalizing the two-point functions of multimatrix operators. Generalized Casimirs constructed from the iterated commutator action of these enhanced symmetries resolve all the multiplicity labels of the bases of matrix operators which diagonalize the two-point function. For the case of U(N) gauge theory with a single complex matrix in the adjoint of the gauge group we have a U(N) x4 global symmetry of the scaling operator at zero coupling. Different choices of commuting sets of Casimirs, for the case of a complex matrix, lead to the restricted Schur basis previously studied in connection with string excitations of giant gravitons and the Brauer basis studied in connection with brane-antibrane systems. More generally these remarks can be extended to the diagonalization for any global symmetry group G. Schur-Weyl duality plays a central role in connecting the enhanced symmetries and the diagonal bases.

  4. Fluctuation-induced forces on an atom near a photonic topological material

    Science.gov (United States)

    Silveirinha, Mário G.; Gangaraj, S. Ali Hassani; Hanson, George W.; Antezza, Mauro

    2018-02-01

    We theoretically study the Casimir-Polder force on an atom in an arbitrary initial state in a rather general electromagnetic environment wherein the materials may have a nonreciprocal bianisotropic dispersive response. It is shown that under the Markov approximation the force has resonant and nonresonant contributions. We obtain explicit expressions for the optical force both in terms of the system Green function and of the electromagnetic modes. We apply the theory to the particular case wherein a two-level system interacts with a topological gyrotropic material, showing that the nonreciprocity enables exotic light-matter interactions and the opportunity to sculpt and tune the Casimir-Polder forces on the nanoscale. With a quasistatic approximation, we obtain a simple analytical expression for the optical force and unveil the crucial role of surface plasmons in fluctuation-induced forces. Finally, we derive the Green function for a gyrotropic material half-space in terms of a Sommerfeld integral.

  5. Success of Arnol'd's method in hierarchy of ocean models

    International Nuclear Information System (INIS)

    Ripa, P.

    1993-01-01

    The method of Arnol'd is used to derive stability conditions of Hamiltonian systems with singular Poisson brackets; notably, those of fluid mechanics. Let the field(s) var-phi(x,t) represent the state variables, and Hamiltonian H [var-phi] and Poisson bracket (.,.) be such that ∂ t var-phi = (var-phi, H). The bracket must have the usual properties; in addition, it may be singular, i.e. there may exist non-trivial functional(s) of state C(var-phi) - called Casimir(s) - such that (C,F) ≡ 0, for any admissible functional of state F(var-phi). Arnol'd's theorms on stability are applied to put constraints on the solutions var-phi(x,t). This model is then applied to the problem of circulation within ocean models, in particular to two families of classical ocean models, primitive equations (PEN) and quasi-geostrophic (QGM) models. These models are layered vertical structures with top and bottom boundaries which may be either rigid or free

  6. From spinning conformal blocks to matrix Calogero-Sutherland models

    Science.gov (United States)

    Schomerus, Volker; Sobko, Evgeny

    2018-04-01

    In this paper we develop further the relation between conformal four-point blocks involving external spinning fields and Calogero-Sutherland quantum mechanics with matrix-valued potentials. To this end, the analysis of [1] is extended to arbitrary dimensions and to the case of boundary two-point functions. In particular, we construct the potential for any set of external tensor fields. Some of the resulting Schrödinger equations are mapped explicitly to the known Casimir equations for 4-dimensional seed conformal blocks. Our approach furnishes solutions of Casimir equations for external fields of arbitrary spin and dimension in terms of functions on the conformal group. This allows us to reinterpret standard operations on conformal blocks in terms of group-theoretic objects. In particular, we shall discuss the relation between the construction of spinning blocks in any dimension through differential operators acting on seed blocks and the action of left/right invariant vector fields on the conformal group.

  7. A Few Integrable Dynamical Systems, Recurrence Operators, Expanding Integrable Models and Hamiltonian Structures by the r -Matrix Method

    International Nuclear Information System (INIS)

    Zhang Yu-Feng; Muhammad, Iqbal; Yue Chao

    2017-01-01

    We extend two known dynamical systems obtained by Blaszak, et al. via choosing Casimir functions and utilizing Novikov–Lax equation so that a series of novel dynamical systems including generalized Burgers dynamical system, heat equation, and so on, are followed to be generated. Then we expand some differential operators presented in the paper to deduce two types of expanding dynamical models. By taking the generalized Burgers dynamical system as an example, we deform its expanding model to get a half-expanding system, whose recurrence operator is derived from Lax representation, and its Hamiltonian structure is also obtained by adopting a new way. Finally, we expand the generalized Burgers dynamical system to the (2+1)-dimensional case whose Hamiltonian structure is derived by Poisson tensor and gradient of the Casimir function. Besides, a kind of (2+1)-dimensional expanding dynamical model of the (2+1)-dimensional dynamical system is generated as well. (paper)

  8. The Treaty of Naples. The closured of the Prince John Casimir and the Polish levy of Medina de las Torres (1638-1642 El Tratado de Nápoles. El encierro del príncipe JuanCasimiro y la leva de polacos de Medina de las Torres (1638-1642

    Directory of Open Access Journals (Sweden)

    Miguel Conde Pazos

    2012-03-01

    Full Text Available Throughout the seventeenth century, the Vasa of Poland and the Habsburg family established a series of contacts which would link to the Catholic Monarchy with the events in Eastern Europe. This article addresses a specific event of these relationships: the closure by the French of Prince Casimir on his way to Spain, and subse-quent negotiations between his half-brother, King Ladislaus IV, and the viceroy of Naples, the Duke of Medina de las Torres, to raise an army of punishment to free the prince. In this negotiation between Naples, Madrid, Vienna and Warsaw, the catholic king diplomacy interacted with leading personalities of the Polish court.Durante todo el siglo XVII los Vasa de Polonia y la familia Habsburgo establecieron una serie de contactos que vincularían a la Monarquía Católica con los acontecimientos de la Europa Oriental. El presente artículo trata un suceso concreto de estas relaciones: el encierro por parte de los franceses del príncipe Casimiro cuando se dirigía hacia España, y las ulteriores negociaciones entre su medio hermano, el rey Ladislao IV, y el virrey de Nápoles, el duque de Medina de las Torres, para levantar un ejército de castigo que liberara al príncipe. En esta negociación entre Nápoles, Madrid, Viena y Varsovia, la diplomacia del rey Católico interactuó con los más destacados personajes de la corte polaca.

  9. Investigations of radiation pressure : optical side-band cooling of a trampoline resonator and the effect of superconductivity on the Casimir force

    NARCIS (Netherlands)

    Eerkens, H.J.

    2017-01-01

    This thesis consists of two subjects, that are both a consequence of radiation pressure. In optomechanics, light is used to influence the motion of a trampoline resonator. It is possible to slow down this motion, cooling it from room temperature to an effective temperature of several milllikelvins,

  10. Vacuum fluctuations and topological Casimir effect in Friedmann-Robertson-Walker cosmologies with compact dimensions

    International Nuclear Information System (INIS)

    Saharian, A.A.; Mkhitaryan, A.L.

    2010-01-01

    We investigate the Wightman function, the vacuum expectation values of the field squared and the energy-momentum tensor for a massless scalar field with general curvature coupling parameter in spatially flat Friedmann-Robertson-Walker universes with an arbitrary number of toroidally compactified dimensions. The topological parts in the expectation values are explicitly extracted and in this way the renormalization is reduced to that for the model with trivial topology. In the limit when the comoving lengths of the compact dimensions are very short compared to the Hubble length, the topological parts coincide with those for a conformal coupling and they are related to the corresponding quantities in the flat spacetime by standard conformal transformation. This limit corresponds to the adiabatic approximation. In the opposite limit of large comoving lengths of the compact dimensions, in dependence of the curvature coupling parameter, two regimes are realized with monotonic or oscillatory behavior of the vacuum expectation values. In the monotonic regime and for non-conformally and non-minimally coupled fields the vacuum stresses are isotropic and the equation of state for the topological parts in the energy density and pressures is of barotropic type. For conformal and minimal couplings the leading terms in the corresponding asymptotic expansions vanish and the vacuum stresses, in general, are anisotropic, though the equation of state remains of barotropic type. In the oscillatory regime, the amplitude of the oscillations for the topological part in the expectation value of the field squared can be either decreasing or increasing with time, whereas for the energy-momentum tensor the oscillations are damping. The limits of validity of the adiabatic approximation are discussed. (orig.)

  11. The impact of telecommuting on the division of labour in the domestic setting

    NARCIS (Netherlands)

    Casimir, G.J.

    2001-01-01

    When people start working at home, it is plausible that the division of labour within the home will change, in particular the division between men and women. Gerda Casimir studied these changes, by analysing the results of an Internet survey, to which 171 respondents reacted. The core of

  12. van der Waals interaction of excited media

    International Nuclear Information System (INIS)

    Sherkunov, Yury

    2005-01-01

    The Casimir interaction between two media of ground-state atoms is well described with the help of the Lifshitz formula depending upon the permittivity of the media. We will show that this formula is in contradiction with experimental evidence for excited atoms. We calculate the Casimir force between two atoms if one or both of them are excited. We use methods of quantum electrodynamics specially derived for the problem. It enables us to take into account the excited-state radiation widths of atoms. Then we calculate the force between the excited atom and medium of ground-state atoms. The results are in agreement with the ones obtained by other authors who used perturbation theory or linear response theory. Generalization of our results to the case of the interaction between two media of excited atoms results in a formula, which is in not only in quantitative, but in qualitative contradiction with the Lifshitz formula. This contradiction disappears if the media of ground-state atoms are considered. Moreover, our result does not include the permittivity of the media. It includes a quantity which differs from the permittivity only for excited atoms. The main features of our results are as follows. The interaction is resonant, the force may be either attractive or repulsive depending on the resonant frequencies of the atoms of different media, and the value of the Casimir force may be several orders of magnitude lager than that predicted by the Lifshitz formula. The features mentioned here are in agreement with known experimental and theoretical evidence obtained by many authors for the interaction of a single excited atom with dielectric media

  13. Quantum effects in the Gowdy T3 cosmology

    International Nuclear Information System (INIS)

    Berger, B.K.

    1984-01-01

    The Gowdy T 3 Cosmology is an exact solution to the vacuum Einstein equations interpreted to be a single polarization of gravitational waves propagating in an anisotropic, spatially inhomogeneous background. The classical behavior is reviewed and related to standard cosmological parameters. Canonical quantization of the dynamical degrees of freedom is reviewed. An adiabatic vacuum state is constructed. Adiabatic regularization if used to obtain non-divergent stress-energy tensor vacuum expectation values. Casimir energy terms due to T 3 imposed discrete modes are evaluated. The vacuum expectation values are analyzed in early and late time limits and evaluated numerically. The regularized expectation value is used as a source for the classical background spacetime in the spirit of semi-classical gravity. An entirely vacuum expectation value source term produces essentially the time reverse of the classical evolution. Classical stress-energy added to the source restores the classical behavior at lates times only. The combined system collapses from infinite to small but non-zero volume and reexpands. The classical singularity is replaced by a symmetric bounce

  14. Zero-point energy of N perfectly conducting concentric cylindrical shells

    International Nuclear Information System (INIS)

    Tatur, K.; Woods, L.M.

    2008-01-01

    The zero-point (Casimir) energy of N perfectly conducting, infinitely long, concentric cylindrical shells is calculated utilizing the mode summation technique. The obtained convergent expression is studied as a function of size, curvature and number of shells. Limiting cases, such as infinitely close shells or infinite radius shells are also investigated

  15. Diagrammatic group theory in quark models

    International Nuclear Information System (INIS)

    Canning, G.P.

    1977-05-01

    A simple and systematic diagrammatic method is presented for calculating the numerical factors arising from group theory in quark models: dimensions, casimir invariants, vector coupling coefficients and especially recoupling coefficients. Some coefficients for the coupling of 3 quark objects are listed for SU(n) and SU(2n). (orig.) [de

  16. Nonabelian gauge fields in the background of magnetic strings

    International Nuclear Information System (INIS)

    Wieczorek, E.

    1993-01-01

    Quantized nonabelian gauge fields are studied in the external classical background of a linear magnetic string. The determination of the gauge field propagator demands a specification of the string by suitable physical limiting procedures. The vacuum energy density is obtained after transforming the background problem into a Casimir problem. (orig.)

  17. Bulk renormalization and particle spectrum in codimension-two brane worlds

    International Nuclear Information System (INIS)

    Salvio, Alberto

    2013-01-01

    We study the Casimir energy due to bulk loops of matter fields in codimension-two brane worlds and discuss how effective field theory methods allow us to use this result to renormalize the bulk and brane operators. In the calculation we explicitly sum over the Kaluza-Klein (KK) states with a new convenient method, which is based on a combined use of zeta function and dimensional regularization. Among the general class of models we consider we include a supersymmetric example, 6D gauged chiral supergravity. Although much of our discussion is more general, we treat in some detail a class of compactifications, where the extra dimensions parametrize a rugby ball shaped space with size stabilized by a bulk magnetic flux. The rugby ball geometry requires two branes, which can host the Standard Model fields and carry both tension and magnetic flux (of the bulk gauge field), the leading terms in a derivative expansion. The brane properties have an impact on the KK spectrum and therefore on the Casimir energy as well as on the renormalization of the brane operators. A very interesting feature is that when the two branes carry exactly the same amount of flux, one half of the bulk supersymmetries survives after the compactification, even if the brane tensions are large. We also discuss the implications of these calculations for the natural value of the cosmological constant when the bulk has two large extra dimensions and the bulk supersymmetry is partially preserved (or completely broken).

  18. Modeling the size dependent pull-in instability of beam-type NEMS using strain gradient theory

    Directory of Open Access Journals (Sweden)

    Ali Koochi

    Full Text Available It is well recognized that size dependency of materials characteristics, i.e. size-effect, often plays a significant role in the performance of nano-structures. Herein, strain gradient continuum theory is employed to investigate the size dependent pull-in instability of beam-type nano-electromechanical systems (NEMS. Two most common types of NEMS i.e. nano-bridge and nano-cantilever are considered. Effects of electrostatic field and dispersion forces i.e. Casimir and van der Waals (vdW attractions have been considered in the nonlinear governing equations of the systems. Two different solution methods including numerical and Rayleigh-Ritz have been employed to solve the constitutive differential equations of the system. Effect of dispersion forces, the size dependency and the importance of coupling between them on the instability performance are discussed.

  19. Extended inflation from higher dimensional theories

    International Nuclear Information System (INIS)

    Holman, R.; Kolb, E.W.; Vadas, S.L.; Wang, Yun.

    1990-04-01

    The possibility is considered that higher dimensional theories may, upon reduction to four dimensions, allow extended inflation to occur. Two separate models are analayzed. One is a very simple toy model consisting of higher dimensional gravity coupled to a scalar field whose potential allows for a first-order phase transition. The other is a more sophisticated model incorporating the effects of non-trivial field configurations (monopole, Casimir, and fermion bilinear condensate effects) that yield a non-trivial potential for the radius of the internal space. It was found that extended inflation does not occur in these models. It was also found that the bubble nucleation rate in these theories is time dependent unlike the case in the original version of extended inflation

  20. Ten physical applications of spectral zeta functions

    CERN Document Server

    Elizalde, Emilio

    1995-01-01

    Zeta-function regularization is a powerful method in perturbation theory. This book is meant as a guide for the student of this subject. Everything is explained in detail, in particular the mathematical difficulties and tricky points, and several applications are given to show how the procedure works in practice (e.g. Casimir effect, gravity and string theory, high-temperature phase transition, topological symmetry breaking). The formulas some of which are new can be used for accurate numerical calculations. The book is to be considered as a basic introduction and a collection of exercises for those who want to apply this regularization procedure in practice.

  1. On the zero point energy of the electromagnetic field in the presence of material media

    International Nuclear Information System (INIS)

    Ferreira, L.A.

    1980-12-01

    The Van der Waals force between two semi-infinite material media separated by a piece of a third material is calculated. In this calculation, a generalization of some works on this theme is made, considering the radiation field delay effect, and impose no kind of electric and magnetic permeability dependence on the field frequency. The zero point energy of electromagnetic field in the presence of rectangular cavities with perfectly conducting walls (epsilon →i infinite) and/or infinitely permeable walls (μ→ infinite), is also calculated. Two kinds of regularization are made. In view of the results obtained modifications in the Casimir's model for the electron are suggested [pt

  2. On boundary superalgebras

    International Nuclear Information System (INIS)

    Doikou, Anastasia

    2010-01-01

    We examine the symmetry breaking of superalgebras due to the presence of appropriate integrable boundary conditions. We investigate the boundary breaking symmetry associated with both reflection algebras and twisted super-Yangians. We extract the generators of the resulting boundary symmetry as well as we provide explicit expressions of the associated Casimir operators.

  3. Superstrate loading effects on the resonant characteristics of high Tc superconducting circular patch printed on anisotropic materials

    Science.gov (United States)

    Bedra, Sami; Bedra, Randa; Benkouda, Siham; Fortaki, Tarek

    2017-12-01

    In this paper, the effects of both anisotropies in the substrate and superstrate loading on the resonant frequency and bandwidth of high-Tc superconducting circular microstrip patch in a substrate-superstrate configuration are investigated. A rigorous analysis is performed using a dyadic Galerkin's method in the vector Hankel transform domain. Galerkin's procedure is employed in the spectral domain where the TM and TE modes of the cylindrical cavity with magnetic side walls are used in the expansion of the disk current. The effect of the superconductivity of the patch is taken into account using the concept of the complex resistive boundary condition. London's equations and the two-fluid model of Gorter and Casimir are used in the calculation of the complex surface impedance of the superconducting circular disc. The accuracy of the analysis is tested by comparing the computed results with previously published data for several anisotropic substrate-superstrate materials. Good agreement is found among all sets of results. The numerical results obtained show that important errors can be made in the computation of the resonant frequencies and bandwidths of the superconducting resonators when substrate dielectric anisotropy, and/or superstrate anisotropy are ignored. Other theoretical results obtained show that the superconducting circular microstrip patch on anisotropic substrate-superstrate with properly selected permittivity values along the optical and the non-optical axes combined with optimally chosen structural parameters is more advantageous than the one on isotropic substrate-superstrate by exhibiting wider bandwidth characteristic.

  4. Finite-size effects in the spectrum of the OSp (3 | 2) superspin chain

    Science.gov (United States)

    Frahm, Holger; Martins, Márcio J.

    2015-05-01

    The low energy spectrum of a spin chain with OSp (3 | 2) supergroup symmetry is studied based on the Bethe ansatz solution of the related vertex model. This model is a lattice realization of intersecting loops in two dimensions with loop fugacity z = 1 which provides a framework to study the critical properties of the unusual low temperature Goldstone phase of the O (N) sigma model for N = 1 in the context of an integrable model. Our finite-size analysis provides strong evidence for the existence of continua of scaling dimensions, the lowest of them starting at the ground state. Based on our data we conjecture that the so-called watermelon correlation functions decay logarithmically with exponents related to the quadratic Casimir operator of OSp (3 | 2). The presence of a continuous spectrum is not affected by a change to the boundary conditions although the density of states in the continua appears to be modified.

  5. Finite-size effects in the spectrum of the OSp(3|2 superspin chain

    Directory of Open Access Journals (Sweden)

    Holger Frahm

    2015-05-01

    Full Text Available The low energy spectrum of a spin chain with OSp(3|2 supergroup symmetry is studied based on the Bethe ansatz solution of the related vertex model. This model is a lattice realization of intersecting loops in two dimensions with loop fugacity z=1 which provides a framework to study the critical properties of the unusual low temperature Goldstone phase of the O(N sigma model for N=1 in the context of an integrable model. Our finite-size analysis provides strong evidence for the existence of continua of scaling dimensions, the lowest of them starting at the ground state. Based on our data we conjecture that the so-called watermelon correlation functions decay logarithmically with exponents related to the quadratic Casimir operator of OSp(3|2. The presence of a continuous spectrum is not affected by a change to the boundary conditions although the density of states in the continua appears to be modified.

  6. Singularities of Poisson structures and Hamiltonian bifurcations

    NARCIS (Netherlands)

    Meer, van der J.C.

    2010-01-01

    Consider a Poisson structure on C8(R3,R) with bracket {, } and suppose that C is a Casimir function. Then {f, g} =<¿C, (¿g x ¿f) > is a possible Poisson structure. This confirms earlier observations concerning the Poisson structure for Hamiltonian systems that are reduced to a one degree of freedom

  7. Force Analysis and Energy Operation of Chaotic System of Permanent-Magnet Synchronous Motor

    Science.gov (United States)

    Qi, Guoyuan; Hu, Jianbing

    2017-12-01

    The disadvantage of a nondimensionalized model of a permanent-magnet synchronous Motor (PMSM) is identified. The original PMSM model is transformed into a Kolmogorov system to aid dynamic force analysis. The vector field of the PMSM is analogous to the force field including four types of torque — inertial, internal, dissipative, and generalized external. Using the feedback thought, the error torque between external torque and dissipative torque is identified. The pitchfork bifurcation of the PMSM is performed. Four forms of energy are identified for the system — kinetic, potential, dissipative, and supplied. The physical interpretations of the decomposition of force and energy exchange are given. Casimir energy is stored energy, and its rate of change is the error power between the dissipative energy and the energy supplied to the motor. Error torque and error power influence the different types of dynamic modes. The Hamiltonian energy and Casimir energy are compared to find the function of each in producing the dynamic modes. A supremum bound for the chaotic attractor is proposed using the error power and Lagrange multiplier.

  8. Statistical Equilibria of Turbulence on Surfaces of Different Symmetry

    Science.gov (United States)

    Qi, Wanming; Marston, Brad

    2012-02-01

    We test the validity of statistical descriptions of freely decaying 2D turbulence by performing direct numerical simulations (DNS) of the Euler equation with hyperviscosity on a square torus and on a sphere. DNS shows, at long times, a dipolar coherent structure in the vorticity field on the torus but a quadrapole on the sphereootnotetextJ. Y-K. Cho and L. Polvani, Phys. Fluids 8, 1531 (1996).. A truncated Miller-Robert-Sommeria theoryootnotetextA. J. Majda and X. Wang, Nonlinear Dynamics and Statistical Theories for Basic Geophysical Flows (Cambridge University Press, 2006). can explain the difference. The theory conserves up to the second-order Casimir, while also respecting conservation laws that reflect the symmetry of the domain. We further show that it is equivalent to the phenomenological minimum-enstrophy principle by generalizing the work by Naso et al.ootnotetextA. Naso, P. H. Chavanis, and B. Dubrulle, Eur. Phys. J. B 77, 284 (2010). to the sphere. To explain finer structures of the coherent states seen in DNS, especially the phenomenon of confinement, we investigate the perturbative inclusion of the higher Casimir constraints.

  9. The Trace Anomaly and Dynamical Vacuum Energy in Cosmology

    CERN Document Server

    Mottola, Emil

    2010-01-01

    The trace anomaly of conformal matter implies the existence of massless scalar poles in physical amplitudes involving the stress-energy tensor. These poles may be described by a local effective action with massless scalar fields, which couple to classical sources, contribute to gravitational scattering processes, and can have long range gravitational effects at macroscopic scales. In an effective field theory approach, the effective action of the anomaly is an infrared relevant term that should be added to the Einstein-Hilbert action of classical General Relativity to take account of macroscopic quantum effects. The additional scalar degrees of freedom contained in this effective action may be understood as responsible for both the Casimir effect in flat spacetime and large quantum backreaction effects at the horizon scale of cosmological spacetimes. These effects of the trace anomaly imply that the cosmological vacuum energy is dynamical, and its value depends on macroscopic boundary conditions at the cosmol...

  10. Quantum field between moving mirrors: A three dimensional example

    Science.gov (United States)

    Hacyan, S.; Jauregui, Roco; Villarreal, Carlos

    1995-01-01

    The scalar quantum field uniformly moving plates in three dimensional space is studied. Field equations for Dirichlet boundary conditions are solved exactly. Comparison of the resulting wavefunctions with their instantaneous static counterpart is performed via Bogolubov coefficients. Unlike the one dimensional problem, 'particle' creation as well as squeezing may occur. The time dependent Casimir energy is also evaluated.

  11. Projection operators and supplementary conditions for superfields with an arbitrary spin

    International Nuclear Information System (INIS)

    Sokatchev, E.

    1975-01-01

    It is shown that a superfield with an external spin j and a nonzero mass contains four non reducible representations of supersymmetry algebra. A general method is proposed for the evolution the representations out of the superfield by using projection operators, derived from Casimir operators. This expansion is also expressed in terms of additional differential conditions

  12. Fundamental Relativistic Rotator

    International Nuclear Information System (INIS)

    Staruszkiewicz, A.

    2008-01-01

    Professor Jan Weyssenhoff was Myron Mathisson's sponsor and collaborator. He introduced a class of objects known in Cracow as '' kreciolki Weyssenhoffa '', '' Weyssenhoff's rotating little beasts ''. The Author describes a particularly simple object from this class. The relativistic rotator described in the paper is such that its both Casimir invariants are parameters rather than constants of motion. (author)

  13. Investigation of paramagnetic saturation in lanthanum manganese nitrate

    NARCIS (Netherlands)

    Flokstra, Jakob; Meijer, H.C.; Bots, G.J.C.; Verheij, W.A.; van der Marel, L.C.

    1973-01-01

    Paramagnetic saturation of lanthanum manganese nitrate, La2Mn3(NO3)12·24H2O, has been investigated at liquid He temperatures in a static as well as a dynamical way. With the aid of the molecular-field theory the Casimir and Du Pré dispersion and absorption curves are adapted explicitly to the

  14. Charge-Induced Fluctuation Forces in Graphitic Nanostructures

    Directory of Open Access Journals (Sweden)

    D. Drosdoff

    2016-01-01

    Full Text Available Charge fluctuations in nanocircuits with capacitor components are shown to give rise to a novel type of long-ranged interaction, which coexist with the regular Casimir–van der Waals force. The developed theory distinguishes between thermal and quantum mechanical effects, and it is applied to capacitors involving graphene nanostructures. The charge fluctuations mechanism is captured via the capacitance of the system with geometrical and quantum mechanical components. The dependence on the distance separation, temperature, size, and response properties of the system shows that this type of force can have a comparable and even dominant effect to the Casimir interaction. Our results strongly indicate that fluctuation-induced interactions due to various thermodynamic quantities can have important thermal and quantum mechanical contributions at the microscale and the nanoscale.

  15. A signature for chameleons in axion-like particle search experiments

    Energy Technology Data Exchange (ETDEWEB)

    Weniger, Christoph [DESY Hamburg (Germany)

    2008-07-01

    Scalar-Tensor theories are well known and viable generalizations of General Relativity. In recent publications, it was shown that these theories can satisfy all astronomical bounds even if the scalar field couples to matter much stronger than gravity. This is due to the fact that the effective mass of the scalar field strongly depends on the density of the ambient matter. We point out that these strongly coupled fields, which were dubbed chameleons, might reveal themselves as an aefterglow'' effect in axion-like particle search experiments due to chameleon photon conversion in a magnetic field. We estimate the parameter space which is accessible by currently available technology and find that afterglow experiments could constrain this parameter space in a way complementary to gravitational and Casimir force experiments.

  16. Laboratory tests on dark energy

    International Nuclear Information System (INIS)

    Beck, Christian

    2006-01-01

    The physical nature of the currently observed dark energy in the universe is completely unclear, and many different theoretical models co-exist. Nevertheless, if dark energy is produced by vacuum fluctuations then there is a chance to probe some of its properties by simple laboratory tests based on Josephson junctions. These electronic devices can be used to perform 'vacuum fluctuation spectroscopy', by directly measuring a noise spectrum induced by vacuum fluctuations. One would expect to see a cutoff near 1.7 THz in the measured power spectrum, provided the new physics underlying dark energy couples to electric charge. The effect exploited by the Josephson junction is a subtile nonlinear mixing effect and has nothing to do with the Casimir effect or other effects based on van der Waals forces. A Josephson experiment of the suggested type will now be built, and we should know the result within the next 3 years

  17. Light moduli in almost no-scale models

    International Nuclear Information System (INIS)

    Buchmueller, Wilfried; Moeller, Jan; Schmidt, Jonas

    2009-09-01

    We discuss the stabilization of the compact dimension for a class of five-dimensional orbifold supergravity models. Supersymmetry is broken by the superpotential on a boundary. Classically, the size L of the fifth dimension is undetermined, with or without supersymmetry breaking, and the effective potential is of no-scale type. The size L is fixed by quantum corrections to the Kaehler potential, the Casimir energy and Fayet-Iliopoulos (FI) terms localized at the boundaries. For an FI scale of order M GUT , as in heterotic string compactifications with anomalous U(1) symmetries, one obtains L∝1/M GUT . A small mass is predicted for the scalar fluctuation associated with the fifth dimension, m ρ 3/2 /(L M). (orig.)

  18. Cross-coupling effects in chemically non-equilibrium viscous compressible flows

    International Nuclear Information System (INIS)

    Kustova, E.V.; Giordano, D.

    2011-01-01

    Graphical abstract: Self-cosistent kinetic-theory description of chemical-reaction rates and mean normal stress in one-temperature viscous compressible gas flows. Reaearch highlights: → In chemically non-equilibrium viscous compressible flows, the rate of each reaction depends on the velocity divergence and rates of all other reactions. → Cross effects between the rates of chemical reactions and normal mean stress can be found in the symmetric form and expressed in terms of the reaction affinities. → In the case of small affinities, the entropy production is unconditionally non-negative; in the case of finite affinities, the entropy production related to the scalar forces has no definite sign. - Abstract: A closed self-consistent description of a one-temperature non-equilibrium reacting flow is presented on the basis of the kinetic theory methods. A general case including internal degrees of freedom, dissociation-recombination and exchange reactions, and arbitrary values of affinities of chemical reactions is considered. Chemical-reaction rates and mean normal stress in viscous compressible flows are studied and a symmetric cross coupling between these terms is found. It is shown that the rate of each chemical reaction and the mean normal stress depend on velocity divergence and affinities of all chemical reactions; the law of mass action is violated in viscous flows. The results obtained in the frame of linear irreversible thermodynamics can be deduced from the proposed model for the particular case of small affinities. The reciprocal Onsager-Casimir relations are verified, the symmetry of kinetic coefficients is demonstrated, and the entropy production in a viscous flow is studied.

  19. Group theoretic derivation of angular functions for the non-relativistic A-body problem in the K-harmonics approach

    International Nuclear Information System (INIS)

    Alcaras, J.A.C.; Ferreira, J.L.

    1975-01-01

    A derivation of an angular basis for the A-body problem, suitable for the K-harmonics method, is presented. Those angular functions are obtained from homogeneous and harmonic polynomials, which are completely specified by labels associated to eigenvalues of the Casimir invariants of subgroups of the 3(A-1)-dimensional orthogonal group, among them, the total angular momentum and its z-projection [pt

  20. A conformal invariant model of localized spinning test particles

    International Nuclear Information System (INIS)

    Duval, C.; Centre National de la Recherche Scientifique, 13 - Marseille; Fliche, H.H.; Centre National de la Recherche Scientifique, 13 - Marseille

    1977-02-01

    A purely classical model of massless test particle with spin s is introduced as the dynamical system defined by the 10 dimensional 0(4,2) co-adjoint orbit with Casimir numbers (s 2 ,0,0). The Mathisson Papapetrou et al. equations of motion in a gravitational field are recovered, and moreover the particle appears to travel on null geodesics. Several implications are discussed

  1. Some activities at CEA related to behaviour of core internals

    International Nuclear Information System (INIS)

    Petrequin, P.

    1998-01-01

    Eighteen transparencies where presented, elaborating some activities at CEA related to behaviour of core internals. After some introduction, ten of the transparencies are essentially a copy of the table of contents of the AMES report no. 11 (report no: EUR 17694 EN). The remaining 6 foils concerned themselves with irradiation experiments in test reactors, namely the IDAHO, CASIMIR and ALEXANDRA experiments

  2. Defects in conformal field theory

    International Nuclear Information System (INIS)

    Billò, Marco; Gonçalves, Vasco; Lauria, Edoardo; Meineri, Marco

    2016-01-01

    We discuss consequences of the breaking of conformal symmetry by a flat or spherical extended operator. We adapt the embedding formalism to the study of correlation functions of symmetric traceless tensors in the presence of the defect. Two-point functions of a bulk and a defect primary are fixed by conformal invariance up to a set of OPE coefficients, and we identify the allowed tensor structures. A correlator of two bulk primaries depends on two cross-ratios, and we study its conformal block decomposition in the case of external scalars. The Casimir equation in the defect channel reduces to a hypergeometric equation, while the bulk channel blocks are recursively determined in the light-cone limit. In the special case of a defect of codimension two, we map the Casimir equation in the bulk channel to the one of a four-point function without defect. Finally, we analyze the contact terms of the stress-tensor with the extended operator, and we deduce constraints on the CFT data. In two dimensions, we relate the displacement operator, which appears among the contact terms, to the reflection coefficient of a conformal interface, and we find unitarity bounds for the latter.

  3. Defects in conformal field theory

    Energy Technology Data Exchange (ETDEWEB)

    Billò, Marco [Dipartimento di Fisica, Università di Torino, and Istituto Nazionale di Fisica Nucleare - sezione di Torino,Via P. Giuria 1 I-10125 Torino (Italy); Gonçalves, Vasco [Centro de Física do Porto,Departamento de Física e Astronomia Faculdade de Ciências da Universidade do Porto, Rua do Campo Alegre 687, 4169-007 Porto (Portugal); ICTP South American Institute for Fundamental Research Instituto de Física Teórica,UNESP - University Estadual Paulista,Rua Dr. Bento T. Ferraz 271, 01140-070, São Paulo, SP (Brazil); Lauria, Edoardo [Institute for Theoretical Physics, KU Leuven, Celestijnenlaan 200D, B-3001 Leuven (Belgium); Meineri, Marco [Perimeter Institute for Theoretical Physics,Waterloo, Ontario, N2L 2Y5 (Canada); Scuola Normale Superiore, and Istituto Nazionale di Fisica Nucleare - sezione di Pisa,Piazza dei Cavalieri 7 I-56126 Pisa (Italy)

    2016-04-15

    We discuss consequences of the breaking of conformal symmetry by a flat or spherical extended operator. We adapt the embedding formalism to the study of correlation functions of symmetric traceless tensors in the presence of the defect. Two-point functions of a bulk and a defect primary are fixed by conformal invariance up to a set of OPE coefficients, and we identify the allowed tensor structures. A correlator of two bulk primaries depends on two cross-ratios, and we study its conformal block decomposition in the case of external scalars. The Casimir equation in the defect channel reduces to a hypergeometric equation, while the bulk channel blocks are recursively determined in the light-cone limit. In the special case of a defect of codimension two, we map the Casimir equation in the bulk channel to the one of a four-point function without defect. Finally, we analyze the contact terms of the stress-tensor with the extended operator, and we deduce constraints on the CFT data. In two dimensions, we relate the displacement operator, which appears among the contact terms, to the reflection coefficient of a conformal interface, and we find unitarity bounds for the latter.

  4. FDE-vdW: A van der Waals inclusive subsystem density-functional theory

    Energy Technology Data Exchange (ETDEWEB)

    Kevorkyants, Ruslan; Pavanello, Michele, E-mail: m.pavanello@rutgers.edu [Department of Chemistry, Rutgers University, Newark, New Jersey 07102 (United States); Eshuis, Henk [Department of Chemistry and Biochemistry, Montclair State University, Montclair, New Jersey 07043 (United States)

    2014-07-28

    We present a formally exact van der Waals inclusive electronic structure theory, called FDE-vdW, based on the Frozen Density Embedding formulation of subsystem Density-Functional Theory. In subsystem DFT, the energy functional is composed of subsystem additive and non-additive terms. We show that an appropriate definition of the long-range correlation energy is given by the value of the non-additive correlation functional. This functional is evaluated using the fluctuation–dissipation theorem aided by a formally exact decomposition of the response functions into subsystem contributions. FDE-vdW is derived in detail and several approximate schemes are proposed, which lead to practical implementations of the method. We show that FDE-vdW is Casimir-Polder consistent, i.e., it reduces to the generalized Casimir-Polder formula for asymptotic inter-subsystems separations. Pilot calculations of binding energies of 13 weakly bound complexes singled out from the S22 set show a dramatic improvement upon semilocal subsystem DFT, provided that an appropriate exchange functional is employed. The convergence of FDE-vdW with basis set size is discussed, as well as its dependence on the choice of associated density functional approximant.

  5. Action principles for the Vlasov equation: Four old, one new

    International Nuclear Information System (INIS)

    Ye, Huanchun; Morrison, P.J.

    1991-01-01

    Action principles for the Vlasov equation are presented. Four previously known action principles, which differ by the choice of dynamical variables, are described and the interrelationship between them discussed. A new action principle called the leaf action, which manifestly preserves the Casimir invariants and possess a single function as the dynamical variable, is presented. The relationship to the noncanonical Hamiltonian formalism is also explored. 21 refs

  6. On the problem of vacuum energy in brane theories

    International Nuclear Information System (INIS)

    Gurwich, Ilya; Rubin, Shimon; Davidson, Aharon

    2009-01-01

    We point out that modern brane theories suffer from a severe vacuum energy problem. To be specific, the Casimir energy associated with the matter fields confined to the brane, is stemming from the one and the same localization mechanism which forms the brane itself, and is thus generically unavoidable. Possible practical solutions are discussed, including in particular spontaneously broken supersymmetry, and quantum mechanically induced brane tension.

  7. Canonical realizations of the Lie algebra sp(2n,R)

    International Nuclear Information System (INIS)

    Havlicek, M.; Lassner, W.

    1975-01-01

    The generators of the Lie algebra of the symplectic group sp(2n,R) are, rezcurently, realied by means of polynomials in the quantum canonical variables qsub(i) and psub(i), i=1,...,d(2n-d);d=1,...,n. These realisations are skew-hermitean, the Casimir operators are realised by constant multiples of identity element and they depend on d free real parameters

  8. Relabeling symmetries in hydrodynamics and magnetohydrodynamics

    International Nuclear Information System (INIS)

    Padhye, N.; Morrison, P.J.

    1996-04-01

    Lagrangian symmetries and concomitant generalized Bianchi identities associated with the relabeling of fluid elements are found for hydrodynamics and magnetohydrodynamics (MHD). In hydrodynamics relabeling results in Ertel's theorem of conservation of potential vorticity, while in MHD it yields the conservation of cross helicity. The symmetries of the reduction from Lagrangian (material) to Eulerian variables are used to construct the Casimir invariants of the Hamiltonian formalism

  9. Chameleon vector bosons

    International Nuclear Information System (INIS)

    Nelson, Ann E.; Walsh, Jonathan

    2008-01-01

    We show that for a force mediated by a vector particle coupled to a conserved U(1) charge, the apparent range and strength can depend on the size and density of the source, and the proximity to other sources. This chameleon effect is due to screening from a light charged scalar. Such screening can weaken astrophysical constraints on new gauge bosons. As an example we consider the constraints on chameleonic gauged B-L. We show that although Casimir measurements greatly constrain any B-L force much stronger than gravity with range longer than 0.1 μm, there remains an experimental window for a long-range chameleonic B-L force. Such a force could be much stronger than gravity, and long or infinite range in vacuum, but have an effective range near the surface of the earth which is less than a micron.

  10. The energy spectrum of electromagnetic normal modes in dissipative media: modes between two metal half spaces

    International Nuclear Information System (INIS)

    Sernelius, Bo E

    2008-01-01

    The energy spectrum of electromagnetic normal modes plays a central role in the theory of the van der Waals and Casimir interaction. Here we study the modes in connection with the van der Waals interaction between two metal half spaces. Neglecting dissipation leads to distinct normal modes with real-valued frequencies. Including dissipation seems to have the effect that these distinct modes move away from the real axis into the complex frequency plane. The summation of the zero-point energies of these modes render a complex-valued result. Using the contour integration, resulting from the use of the generalized argument principle, gives a real-valued and different result. We resolve this contradiction and show that the spectrum of true normal modes forms a continuum with real frequencies

  11. Hairy AdS solitons

    International Nuclear Information System (INIS)

    Anabalón, Andrés; Astefanesei, Dumitru; Choque, David

    2016-01-01

    We construct exact hairy AdS soliton solutions in Einstein-dilaton gravity theory. We examine their thermodynamic properties and discuss the role of these solutions for the existence of first order phase transitions for hairy black holes. The negative energy density associated to hairy AdS solitons can be interpreted as the Casimir energy that is generated in the dual filed theory when the fermions are antiperiodic on the compact coordinate.

  12. Note on the narrow 3.1 GeV (Λ p-bar + pions)

    International Nuclear Information System (INIS)

    Chan Hongmo; Tsou Sheungtsun

    1987-02-01

    It is pointed out that the narrow exotic U(3.105) (Λ p-bar + pions) state reported at CERN and Serpukhov and its companion at 3.410 GeV, fall neatly on top of the spectrum predicted nine years ago for 'M-baryoniums' and agree with the expected decay characteristics. Further, when so interpreted, their spacing gives a direct measure of the colour Casimir factor in the string tension. (author)

  13. Degenerate odd Poisson bracket on Grassmann variables

    International Nuclear Information System (INIS)

    Soroka, V.A.

    2000-01-01

    A linear degenerate odd Poisson bracket (antibracket) realized solely on Grassmann variables is proposed. It is revealed that this bracket has at once three Grassmann-odd nilpotent Δ-like differential operators of the first, second and third orders with respect to the Grassmann derivatives. It is shown that these Δ-like operators, together with the Grassmann-odd nilpotent Casimir function of this bracket, form a finite-dimensional Lie superalgebra

  14. Quantum levitation by left-handed metamaterials

    Energy Technology Data Exchange (ETDEWEB)

    Leonhardt, Ulf; Philbin, Thomas G [School of Physics and Astronomy, University of St Andrews, North Haugh, St Andrews KY16 9SS (United Kingdom)

    2007-08-15

    Left-handed metamaterials make perfect lenses that image classical electromagnetic fields with significantly higher resolution than the diffraction limit. Here, we consider the quantum physics of such devices. We show that the Casimir force of two conducting plates may turn from attraction to repulsion if a perfect lens is sandwiched between them. For optical left-handed metamaterials, this repulsive force of the quantum vacuum may levitate ultra-thin mirrors.

  15. Quantum levitation by left-handed metamaterials

    International Nuclear Information System (INIS)

    Leonhardt, Ulf; Philbin, Thomas G

    2007-01-01

    Left-handed metamaterials make perfect lenses that image classical electromagnetic fields with significantly higher resolution than the diffraction limit. Here, we consider the quantum physics of such devices. We show that the Casimir force of two conducting plates may turn from attraction to repulsion if a perfect lens is sandwiched between them. For optical left-handed metamaterials, this repulsive force of the quantum vacuum may levitate ultra-thin mirrors

  16. Gravitational states of antihydrogen near material surface

    Energy Technology Data Exchange (ETDEWEB)

    Voronin, Alexei Yu., E-mail: dr.a.voronin@gmail.com [P.N. Lebedev Physical Institute (Russian Federation); Froelich, Piotr [Uppsala University, Department of Quantum Chemistry (Sweden); Nesvizhevsky, Valery V. [Institut Laue-Langevin (ILL) (France)

    2012-12-15

    We present a theoretical study of the motion of antihydrogen atoms in the Earth's gravitational field near a material surface. We predict the existence of long-living quasistationary states of antihydrogen in a superposition of the gravitational and Casimir-van der Waals potentials of the surface. We suggest an interferometric method of measuring the energy difference between such gravitational states, hence the gravitational mass of antihydrogen.

  17. Infra-red fixed points in supersymmetry

    Indian Academy of Sciences (India)

    ¾c /font>, and c stands for the color quadratic Casimir of the field. Fixed points arise when R* ¼ or when R*. /nobr>. ´S-½. µ ´r ·b¿µ. The stability of the solutions may be tested by linearizing the system about the fixed points. For the non-trivial fixed points we need to consider the eigenvalues of the stability matrix whose ...

  18. Hairy AdS solitons

    Energy Technology Data Exchange (ETDEWEB)

    Anabalón, Andrés, E-mail: andres.anabalon@uai.cl [Departamento de Ciencias, Facultad de Artes Liberales and Facultad de Ingeniería y Ciencias, Universidad Adolfo Ibáñez, Av. Padre Hurtado 750, Viña del Mar (Chile); Astefanesei, Dumitru, E-mail: dumitru.astefanesei@pucv.cl [Instituto de Física, Pontificia Universidad Católica de Valparaíso, Casilla 4059, Valparaíso (Chile); Choque, David, E-mail: brst1010123@gmail.com [Instituto de Física, Pontificia Universidad Católica de Valparaíso, Casilla 4059, Valparaíso (Chile); Universidad Técnica Federico Santa María, Av. España 1680, Valparaíso (Chile)

    2016-11-10

    We construct exact hairy AdS soliton solutions in Einstein-dilaton gravity theory. We examine their thermodynamic properties and discuss the role of these solutions for the existence of first order phase transitions for hairy black holes. The negative energy density associated to hairy AdS solitons can be interpreted as the Casimir energy that is generated in the dual filed theory when the fermions are antiperiodic on the compact coordinate.

  19. Multiplet mass splitting in a gravitational field

    International Nuclear Information System (INIS)

    Maia, M.D.

    An expression for the mass splitting of particles belonging to the same spin multiplet defined in a space-time of general relativity is derived. The geometrical symmetry is a subgroup of SO(r,s), 9 >=r > 3, 5 >=s >=1, the mass operator being proportional to the second order Casimir operator of that subgroup. A brief analysis of the calculated values as compared to the experimental data is included. (Author) [pt

  20. Fluctuation-induced long-range interactions in polymer systems

    International Nuclear Information System (INIS)

    Semenov, A N; Obukhov, S P

    2005-01-01

    We discover a new universal long-range interaction between solid objects in polymer media. This polymer-induced interaction is directly opposite to the van der Waals attraction. The predicted effect is deeply related to the classical Casimir interactions, providing a unique example of universal fluctuation-induced repulsion rather than normal attraction. This universal repulsion comes from the subtracted soft fluctuation modes in the ideal counterpart of the real polymer system. The effect can also be interpreted in terms of subtracted (ghost) large-scale polymer loops. We establish the general expressions for the energy of polymer-induced interactions for arbitrary solid particles in a concentrated polymer system. We find that the correlation function of the polymer density in a concentrated solution of very long chains follows a scaling law rather than an exponential decay at large distances. These novel universal long-range interactions can be of importance in various polymer systems. We discuss the ways to observe/simulate these fluctuation-induced effects

  1. Quantum surface tension in ideal gases

    International Nuclear Information System (INIS)

    Sisman, A.

    2005-01-01

    Due to wave character of atoms, an ideal gas confined in a finite domain exhibits Casimir like size effects. These effects become appreciable in a domain with at least one dimension in the order of micron. On this scale, thermodynamic state functions of an ideal gas become shape and size dependent and some new effects appear. In the literature, only some domains of regular shapes have been considered. In this study, the results are generalized to a domain of an arbitrary shape by using Weyl s conjecture for density of states. It is seen that free energy expression of an ideal Maxwellian gas consists of a classical volume dependent term and also a quantum originated surface dependent term, which causes a quantum surface tension. In a rectangular box filled by an ideal gas and separated by a movable wall into two parts, it is shown that a lateral force appears on the movable wall due to quantum surface tension

  2. On boson condensation considering a generalized Casimir example

    Science.gov (United States)

    Voigt, K.

    1990-12-01

    From the concept of generalized condensation [M. Van den Berg, J. T. Lewis, and J. V. Pulè, Helv. Phys. Acta 59, 1271 (1986)] it is known that two critical densities ρc and ρm exist for a free boson gas. Density ρc is the classical one and ρm is the critical density below which there can be no macroscopic occupation of ground state. A free boson gas is studied in a weak external potential which behaves asymptotically like ||x1||α1+||x2||α2+ṡṡṡ +||xd||αd near the origin. It is shown that there are only two possibilities to get ρc<ρm<∞, namely, α1=α2=∞ and d≥3 (this corresponds to Dirichlet boundary conditions), and α1=2 and d≥2 (i.e., a harmonic oscillator).

  3. Spinor Casimir densities for a spherical shell in the global monopole spacetime

    International Nuclear Information System (INIS)

    Saharian, A A; Mello, E R Bezerra de

    2004-01-01

    We investigate the vacuum expectation values of the energy-momentum tensor and the fermionic condensate associated with a massive spinor field obeying the MIT bag boundary condition on a spherical shell in the global monopole spacetime. In order to do that, we use the generalized Abel-Plana summation formula. As we shall see, this procedure allows us to extract from the vacuum expectation values the contribution coming from the unbounded spacetime and to explicitly present the boundary induced parts. As regards the boundary induced contribution, two distinct situations are examined: the vacuum average effects inside and outside the spherical shell. The asymptotic behaviour of the vacuum densities is investigated near the sphere centre and near the surface, and at large distances from the sphere. In the limit of strong gravitational field corresponding to small values of the parameter describing the solid angle deficit in the global monopole geometry, the sphere induced expectation values are exponentially suppressed. We discuss, as a special case, the fermionic vacuum densities for the spherical shell on the background of the Minkowski spacetime. Previous approaches to this problem within the framework of the QCD bag models have been global and our calculation is a local extension of these contributions

  4. Antimatter Production at a Potential Boundary

    Science.gov (United States)

    LaPointe, Michael R.; Reddy, Dhanireddy (Technical Monitor)

    2001-01-01

    Current antiproton production techniques rely on high-energy collisions between beam particles and target nuclei to produce particle and antiparticle pairs, but inherently low production and capture efficiencies render these techniques impractical for the cost-effective production of antimatter for space propulsion and other commercial applications. Based on Dirac's theory of the vacuum field, a new antimatter production concept is proposed in which particle-antiparticle pairs are created at the boundary of a steep potential step formed by the suppression of the local vacuum fields. Current antimatter production techniques are reviewed, followed by a description of Dirac's relativistic quantum theory of the vacuum state and corresponding solutions for particle tunneling and reflection from a potential barrier. The use of the Casimir effect to suppress local vacuum fields is presented as a possible technique for generating the sharp potential gradients required for particle-antiparticle pair creation.

  5. Lie superalgebras

    International Nuclear Information System (INIS)

    Berezin, F.A.

    1977-01-01

    Generalization of the Laplace-Casimir operator theory on the Lie supergroups is considered. The main result is the formula for radial parts of the Laplace operators under some general assumptions about the Lie supergroup. In particular these assumptions are valid for the Lie suppergroups U(p,g) and C (m,n). The first one is the analogue of the unitary group, the second one is the analogue of the linear group of canonical transformations

  6. The Cardy-Verlinde formula and asymptotically de Sitter brane universe

    International Nuclear Information System (INIS)

    Youm, Donam

    2001-11-01

    We consider the brane universe in the bulk background of the topological AdS-Schwarzschild black holes, where the brane tension takes larger value than the fine-tuned value. The resulting universe is radiation dominated and has positive cosmological constant. We obtain the associated cosmological Cardy formula and the Cardy-Verlinde formula. We also derive the Hubble and the Bekenstein entropy bounds from the conjectured holography bound on the Casimir entropy. (author)

  7. Quantum deformed magnon kinematics

    OpenAIRE

    Gómez, César; Hernández Redondo, Rafael

    2007-01-01

    The dispersion relation for planar N=4 supersymmetric Yang-Mills is identified with the Casimir of a quantum deformed two-dimensional kinematical symmetry, E_q(1,1). The quantum deformed symmetry algebra is generated by the momentum, energy and boost, with deformation parameter q=e^{2\\pi i/\\lambda}. Representing the boost as the infinitesimal generator for translations on the rapidity space leads to an elliptic uniformization with crossing transformations implemented through translations by t...

  8. Adjoint string breaking in the pseudoparticle approach

    International Nuclear Information System (INIS)

    Szasz, Christian; Wagner, Marc

    2008-01-01

    We apply the pseudoparticle approach to SU(2) Yang-Mills theory and perform a detailed study of the potential between two static charges for various representations. Whereas for charges in the fundamental representation we find a linearly rising confining potential, we clearly observe string breaking, when considering charges in the adjoint representation. We also demonstrate Casimir scaling and compute gluelump masses for different spin and parity. Numerical results are in qualitative agreement with lattice results.

  9. Atomic interferometers in an optical lattice

    International Nuclear Information System (INIS)

    Pelle, Bruno

    2013-01-01

    The aim of the ForCa-G project, for Casimir force and short range Gravitation, lies into the measurement of short range forces between atoms and a mirror using atomic interferometry techniques. Particularly, the Casimir-Polder force and the pursuit of short range gravitational tests in the frame of potential deviations of Newton's law are aimed. This experiment is based on the trapping of neutral atoms in a 1D vertical optical lattice, where the energy eigenvalues of the Hamiltonian describing this system is the so-called Wannier-Stark ladder of discrete energy states localized in each lattice well. This work constitutes a demonstration of principle of this project with atoms set far from the mirror. Each energy state is thus separated from the one of the adjacent well by the potential energy increment between those two wells, called the Bloch frequency ν B . Then, atomic interferometers are realized in the lattice using Raman or microwave pulses where the trapped atomic wave functions are placed, and then recombined, in a superposition of states between different energy states localized either in the same well, either in adjacent wells. This work presents the study of different kinds of atomic interferometers in this optical lattice, characterized in terms of sensibility and systematic effects on the Bloch frequency measurement. One of the studied interferometers accessed to a sensitivity on the Bloch frequency of σ δ ν B /ν B =9.0x10 -6 at 1∼s in relative, which integrates until σ δ ν B /ν B =1. 10 -7 in 2800∼s. This corresponds to a state-of-the-art measurement of the gravity acceleration g for a trapped atomic gravimeter. (author)

  10. Relativistic quantum channel of communication through field quanta

    International Nuclear Information System (INIS)

    Cliche, M.; Kempf, A.

    2010-01-01

    Setups in which a system Alice emits field quanta that a system Bob receives are prototypical for wireless communication and have been extensively studied. In the most basic setup, Alice and Bob are modeled as Unruh-DeWitt detectors for scalar quanta, and the only noise in their communication is due to quantum fluctuations. For this basic setup, we construct the corresponding information-theoretic quantum channel. We calculate the classical channel capacity as a function of the spacetime separation, and we confirm that the classical as well as the quantum channel capacity are strictly zero for spacelike separations. We show that this channel can be used to entangle Alice and Bob instantaneously. Alice and Bob are shown to extract this entanglement from the vacuum through a Casimir-Polder effect.

  11. On a low energy, strong interaction model, unifying mesons and baryons

    International Nuclear Information System (INIS)

    Kalafatis, D.

    1993-03-01

    This thesis is concerned with the study of a unified theory of mesons and baryons. An effective Lagrangian with the low mass mesons, generalizing the Skyrme model, is constructed. The vector meson fields are introduced as gauge fields in the linear sigma model instead of the non linear sigma model. Topological soliton solutions of the model are examined and the nucleon-nucleon interaction in the product approximation is investigated. The leading correction to the classical skyrmion mass, the Casimir energy, is evaluated. The problem of the stability of topological solitons when vector fields enter the chiral Lagrangian is also studied. It is shown that the soliton is stable in very much the same way as with the ωmeson and that peculiar classical doublet solutions do not exist

  12. A Hamiltonian five-field gyrofluid model

    Energy Technology Data Exchange (ETDEWEB)

    Keramidas Charidakos, I.; Waelbroeck, F. L.; Morrison, P. J. [Institute for Fusion Studies and Department of Physics, The University of Texas at Austin, Austin, TX 78712 (United States)

    2015-11-15

    A Lie-Poisson bracket is presented for a five-field gyrofluid model, thereby showing the model to be Hamiltonian. The model includes the effects of magnetic field curvature and describes the evolution of the electron and ion gyro-center densities, the parallel component of the ion and electron velocities, and the ion temperature. The quasineutrality property and Ampère's law determine, respectively, the electrostatic potential and magnetic flux. The Casimir invariants are presented, and shown to be associated with five Lagrangian invariants advected by distinct velocity fields. A linear, local study of the model is conducted both with and without Landau and diamagnetic resonant damping terms. Stability criteria and dispersion relations for the electrostatic and the electromagnetic cases are derived and compared with their analogs for fluid and kinetic models.

  13. Green's dyadic approach of the self-stress on a dielectric-diamagnetic cylinder with non-uniform speed of light

    International Nuclear Information System (INIS)

    Cavero-Pelaez, I; Milton, K A

    2006-01-01

    We present a Green's dyadic formulation to calculate the Casimir energy for a dielectric-diamagnetic cylinder with the speed of light differing inside and outside. Although the result is in general divergent, special cases are meaningful. It is pointed out how the self-stress on a purely dielectric cylinder vanishes through second order in the deviation of the permittivity from its vacuum value, in agreement with the result calculated from the sum of van der Waals forces

  14. Loop averages and partition functions in U(N) gauge theory on two-dimensional manifolds

    International Nuclear Information System (INIS)

    Rusokov, B.Y.

    1990-01-01

    Loop averages and partition functions in the U(N) gauge theory are calculated for loops without intersections on arbitrary two-dimensional manifolds including non-orientable one. The physical quantities are directly expressed through geometrical characteristics of a manifold (areas enclosed by loops and the genus) and gauge group parameters (Casimir eigenvalues and dimensions of the irreducible representations). It is shown that, from the physical quantities' point of view, non-orientability of the manifold is equivalent to its non-compactness

  15. Hamiltonian formalism of Whitham-type hierarchies and topological Landau-Ginsburg models

    International Nuclear Information System (INIS)

    Dubrovin, B.A.

    1992-01-01

    We show that the bi-hamiltonian structure of the averaged Gelfand-Dikii hierarchy is involved in the Landau-Ginsburg topological models (for A n -Series): The Casimirs for the first P.B. give the correct coupling parameters for the perturbed topological minimal model; the correspondence {coupling parameters}→{primary fields} is determined by the second P.B. The partition function (at the tree level) and the chiral algebra for LG minimal models are calculated for any genus g. (orig.)

  16. Influence of random roughness on the adhesion between metal surfaces due to capillary condensation

    OpenAIRE

    van Zwol, P. J.; Palasantzas, G.; De Hosson, J. Th. M.

    2007-01-01

    The capillary force was measured by atomic force microscopy between a gold coated sphere mounted on a cantilever and gold surfaces with different roughnesses. For smooth surfaces the capillary adhesive force surpasses in magnitude any dispersion, e.g., van der Waals/Casimir and/or electrostatic forces. A substantial decrease in the capillary force was observed by increasing the roughness ampltitude a few nanometers in the range of 1-10 nm. From these measurements two limits can be defined: a ...

  17. MOVEMENT AND MANEUVER IN DEEP SPACE: A Framework to Leverage Advanced Propulsion

    Science.gov (United States)

    2018-04-01

    the Casimir force—which is analogous to a pressure imbalance created by a reduction in air density ( think Bernoulli’s principle).53 Because the...many bets ” scenario. If the bets are well vetted, like the BPP model, then even a null or sub-optimal result is a valuable 37 pay-off in terms of...we must think of deep space exploration as imperative–too important to be relegated to simple political interest. 115 “Worldometers” on Worldometers

  18. Dynamical symmetries of two-dimensional systems in relativistic quantum mechanics

    International Nuclear Information System (INIS)

    Zhang Fulin; Song Ci; Chen Jingling

    2009-01-01

    The two-dimensional Dirac Hamiltonian with equal scalar and vector potentials has been proved commuting with the deformed orbital angular momentum L. When the potential takes the Coulomb form, the system has an SO(3) symmetry, and similarly the harmonic oscillator potential possesses an SU(2) symmetry. The generators of the symmetric groups are derived for these two systems separately. The corresponding energy spectra are yielded naturally from the Casimir operators. Their non-relativistic limits are also discussed

  19. Stiff self-interacting strings at high temperature QCD

    Directory of Open Access Journals (Sweden)

    S Bakry A.

    2018-01-01

    Full Text Available We investigate the implications of Nambu-Goto (NG, Lüscher Weisz (LW and Polyakov-Kleinert (PK effective string actions for the Casimir energy and the width of the quantum delocalization of the string in 4-dim pure SU(3 Yang-Mills lattice gauge theory. At a temperature closer to the critical point T/Tc=0.9, we found that the next to leading-order (NLO contributions from the expansion of the NG string in addition to the boundary terms in LW action to decrease the deviations from the lattice data in the intermediate distance scales for both the quark-antiquark QQ̅ potential and broadening of the color tube compared to the free string approximation. We conjecture possible stiffness of the QCD string through studying the effects of extrinsic curvature term in PK action and find a good fitting behavior for the lattice Monte-Carlo data at both long and intermediate quark separations regions.

  20. Stiff self-interacting strings at high temperature QCD

    Science.gov (United States)

    S Bakry, A.; Chen, X.; Deliyergiyev, M.; Galal, A.; Khalaf, A.; M Pengming, P.

    2018-03-01

    We investigate the implications of Nambu-Goto (NG), Lüscher Weisz (LW) and Polyakov-Kleinert (PK) effective string actions for the Casimir energy and the width of the quantum delocalization of the string in 4-dim pure SU(3) Yang-Mills lattice gauge theory. At a temperature closer to the critical point T/Tc=0.9, we found that the next to leading-order (NLO) contributions from the expansion of the NG string in addition to the boundary terms in LW action to decrease the deviations from the lattice data in the intermediate distance scales for both the quark-antiquark QQ̅ potential and broadening of the color tube compared to the free string approximation. We conjecture possible stiffness of the QCD string through studying the effects of extrinsic curvature term in PK action and find a good fitting behavior for the lattice Monte-Carlo data at both long and intermediate quark separations regions.

  1. Effect of the Gribov horizon on the Polyakov loop and vice versa

    Energy Technology Data Exchange (ETDEWEB)

    Canfora, F.E. [Centro de Estudios Cientificos (CECS), Valdivia (Chile); Dudal, D. [KU Leuven Campus Kortrijk, KULAK, Department of Physics, Kortrijk (Belgium); Ghent University, Department of Physics and Astronomy, Gent (Belgium); Justo, I.F. [Ghent University, Department of Physics and Astronomy, Gent (Belgium); UERJ, Universidade do Estado do Rio de Janeiro, Departamento de Fisica Teorica, Instituto de Fisica, Maracana, Rio de Janeiro (Brazil); Pais, P. [Centro de Estudios Cientificos (CECS), Valdivia (Chile); Universite Libre de Bruxelles and International Solvay Institutes, Physique Theorique et Mathematique, Brussels (Belgium); Rosa, L. [Universita di Napoli Federico II, Dipartimento di Fisica, Monte S. Angelo (Italy); INFN, Sezione di Napoli, Monte S. Angelo (Italy); Vercauteren, D. [Duy Tan University, Institute of Research and Development, Da Nang (Viet Nam)

    2015-07-15

    We consider finite-temperature SU(2) gauge theory in the continuum formulation, which necessitates the choice of a gauge fixing. Choosing the Landau gauge, the existing gauge copies are taken into account by means of the Gribov-Zwanziger quantization scheme, which entails the introduction of a dynamical mass scale (Gribov mass) directly influencing the Green functions of the theory. Here, we determine simultaneously the Polyakov loop (vacuum expectation value) and Gribov mass in terms of temperature, by minimizing the vacuum energy w.r.t. the Polyakov-loop parameter and solving the Gribov gap equation. Inspired by the Casimir energy-style of computation, we illustrate the usage of Zeta function regularization in finite-temperature calculations. Our main result is that the Gribov mass directly feels the deconfinement transition, visible from a cusp occurring at the same temperature where the Polyakov loop becomes nonzero. In this exploratory work we mainly restrict ourselves to the original Gribov-Zwanziger quantization procedure in order to illustrate the approach and the potential direct link between the vacuum structure of the theory (dynamical mass scales) and (de)confinement. We also present a first look at the critical temperature obtained from the refined Gribov-Zwanziger approach. Finally, a particular problem for the pressure at low temperatures is reported. (orig.)

  2. The calculation of multiquark hadrons by the quark model baryon, meson and multiquark states

    International Nuclear Information System (INIS)

    Takeuchi, Sachiko; Takizawa, Makoto; Yasui, Shigehiro

    2011-01-01

    The 1st new hadron summer school related with the new science field, 'the comprehensive research of new hadron states searched by variable flavor number scheme', was held on August 18-20, 2010. This report is one of the 'quark model' lectures. The chapter 1 describes following problems: 1. The background and the significance as a phenomenological theory of the constituent quark model. 2. The introduction of the quark model. 3. The summary of the properties of hadrons in which the quark model can apply to three quarks (qqq) and, one quark and antiquark (q - q) configurations, but is difficult to apply to some configurations. 4. A brief summary of exotic hadrons and recent problems. In chapter 2, the introduction and some exercises of the stochastic variational method are reported as a technique of solving spatial part of multiquark states. In the chapter 3, spins and color parts in multiquark states are calculated. The group theory is applied to calculate the eigenvalues of the Casimir operators of SU(2), SU(3) and SU(6). In the problems of being unable to apply Casimir operators, the direct matrix diagonalization method, m-scheme, is employed for interacting quarks and for the interaction involving quark mass. To find the attractive interaction in tetraquark (QQqq-bar) state is given as an exercise problem. (Y. Kazumata)

  3. Holographic description of Kerr-Bolt-AdS-dS spacetimes

    International Nuclear Information System (INIS)

    Chen, B.; Ghezelbash, A.M.; Kamali, V.; Setare, M.R.

    2011-01-01

    We show that there exists a holographic 2D CFT description of a Kerr-Bolt-AdS-dS spacetime. We first consider the wave equation of a massless scalar field propagating in extremal Kerr-Bolt-AdS-dS spacetimes and find in the 'near region', the wave equation in extremal limit could be written in terms of the SL(2,R) quadratic Casimir. This suggests that there exist dual CFT descriptions of these black holes. In the probe limit, we compute the scattering amplitudes of the scalar off the extremal black holes and find perfect agreement with the CFT prediction. Furthermore we study the holographic description of the generic four-dimensional non-extremal Kerr-Bolt-AdS-dS black holes. We find that if focusing on the near-horizon region, for the massless scalar scattering in the low-frequency limit, the radial equation could still be rewritten as the SL(2,R) quadratic Casimir, suggesting the existence of dual 2D description. We read the temperatures of the dual CFT from the conformal coordinates and obtain the central charges by studying the near-horizon geometry of near-extremal black holes. We recover the macroscopic entropy from the microscopic counting. We also show that for the super-radiant scattering, the retarded Green's functions and the corresponding absorption cross sections are in perfect match with CFT prediction.

  4. Development of a second generation torsion balance based on a spherical superconducting suspension

    Science.gov (United States)

    Hammond, Giles D.; Speake, Clive C.; Matthews, Anthony J.; Rocco, Emanuele; Peña-Arellano, Fabian

    2008-02-01

    This paper describes the development of a second generation superconducting torsion balance to be used for a precision measurement of the Casimir force and a short range test of the inverse square law of gravity at 4.2K. The instrument utilizes niobium (Nb) as the superconducting element and employs passive damping of the parasitic modes of oscillation. Any contact potential difference between the torsion balance and its surroundings is nulled to within ≈50mV by applying known DC biases and fitting the resulting parabolic relationship between the measured torque and the applied voltage. A digital proportional-integral-derivative servo system has been developed and characterized in order to control the azimuthal position of the instrument. The angular acceleration and displacement noise are currently limited by the capacitive sensor at the level 3×10-8rads-2/√Hz and 30nm/√Hz at 100mHz. The possibility of lossy dielectric coatings on the surface of the torsion balance test masses is also investigated. Our measurements show that the loss angles δ are (1.5±2.3)×10-4 and (2.0±2.2)×10-4 at frequencies of 5 and 10mHz, respectively. These values of loss are not significant sources of error for measurements of the Casimir force using this experimental setup.

  5. An efficient and general numerical method to compute steady uniform vortices

    Science.gov (United States)

    Luzzatto-Fegiz, Paolo; Williamson, Charles H. K.

    2011-07-01

    Steady uniform vortices are widely used to represent high Reynolds number flows, yet their efficient computation still presents some challenges. Existing Newton iteration methods become inefficient as the vortices develop fine-scale features; in addition, these methods cannot, in general, find solutions with specified Casimir invariants. On the other hand, available relaxation approaches are computationally inexpensive, but can fail to converge to a solution. In this paper, we overcome these limitations by introducing a new discretization, based on an inverse-velocity map, which radically increases the efficiency of Newton iteration methods. In addition, we introduce a procedure to prescribe Casimirs and remove the degeneracies in the steady vorticity equation, thus ensuring convergence for general vortex configurations. We illustrate our methodology by considering several unbounded flows involving one or two vortices. Our method enables the computation, for the first time, of steady vortices that do not exhibit any geometric symmetry. In addition, we discover that, as the limiting vortex state for each flow is approached, each family of solutions traces a clockwise spiral in a bifurcation plot consisting of a velocity-impulse diagram. By the recently introduced "IVI diagram" stability approach [Phys. Rev. Lett. 104 (2010) 044504], each turn of this spiral is associated with a loss of stability for the steady flows. Such spiral structure is suggested to be a universal feature of steady, uniform-vorticity flows.

  6. Introduction to supersymmetry in particle and nuclear physics

    International Nuclear Information System (INIS)

    Castanos, O.; Frank, A.; Urrutia, L.

    1981-01-01

    This book constitutes the proceedings of an International School of Supersymmetry held in Mexico City in 1981. Lectures presented include an introduction to supersymmetry (symmetries in relativistic quantum field theory, supersymmetry in quantum field theory, Dirac matrices and Majorana spinors, supersymmetric Yang-Mills theory, scalar multiplet and auxiliary fields, supergravity, N=1 supersymmetric theories, extended supersymmetry algebras, representations of extended supersymmetry, N=4 supersymmetric Yang-Mills theory, extended supergravity), superfields (irreducible representations and chiral superfields, invariants and ''tensor calculus,'' gauge superfield, N=1 supergravity), grand unification with and without supersymmetry (supersymmetric models), Yang-Mills theories with global and local supersymmetry (Higgs and Superhiggs effect in unified field theories), and supergroups and their representations (fermion and Grassmann numbers, supertrace and superdeterminant, harmonic oscillator representation, the Tilde operator, eigenvalues of Casimir operators, branching rules, Kac-Dynkin diagrams and supertableaux)

  7. On the 'near to minimal' canonical realizations of the Lie algebra Csub(n)

    International Nuclear Information System (INIS)

    Havlicek, M.; Lassner, W.

    1975-01-01

    It is proved that canonical realizations of the Lie algebra Csub(n) in the quotient division ring Dsub(2(2n-2)) of the Weyl algebra Wsub(2(2n-2)) in 2n-2 quantum canonical pairs are, in a definite sense, related to the standard minimal one in Dsub(2n) contains Dsub(2(2n-2)). Further, in any realization of Csub(n) in Wsub(2(2n-1)) all Casimir operators are realized by multiples of identity element

  8. Neutrino stress tensor regularization in two-dimensional space-time

    International Nuclear Information System (INIS)

    Davies, P.C.W.; Unruh, W.G.

    1977-01-01

    The method of covariant point-splitting is used to regularize the stress tensor for a massless spin 1/2 (neutrino) quantum field in an arbitrary two-dimensional space-time. A thermodynamic argument is used as a consistency check. The result shows that the physical part of the stress tensor is identical with that of the massless scalar field (in the absence of Casimir-type terms) even though the formally divergent expression is equal to the negative of the scalar case. (author)

  9. Instabilities of higher dimensional compactifications

    International Nuclear Information System (INIS)

    Accetta, F.S.

    1987-02-01

    Various schemes for cosmological compactification of higher dimensional theories are considered. Possible instabilities which drive the ground state with static internal space to de Sitter-like expansion of all dimensions are discussed. These instabilities are due to semiclassical barrier penetration and classical thermal fluctuations. For the case of the ten dimensional Chapline-Manton action, it is possible to avoid such difficulties by balancing one-loop Casimir corrections against monopole contributions from the field strength H/sub MNP/ and fermionic condensates. 10 refs

  10. Thermophysical Properties of Matter - The TPRC Data Series. Volume 2. Thermal Conductivity - Nonmetallic Solids

    Science.gov (United States)

    1971-01-01

    Rept. NYO-6451, 1-16, 1955. [AD 80 699] Ratcliffe, E.H.. Phys. and Chem. of Glasses, 1.(3), 103-4, 1960. Sujak, B. , ACTA Physica Polonica , 20(2...1954. Boundary Resistance 61. Casimir, H. B. G., "Note on the Conduction of Heat in Crystals," Physica , 5(6), 495-500, 1938. 62. Berman, R., Simon...TP! r, f Theory, Estimation, and Measurement 39« Liquids by a Nonstationary Method." Physica , 19(3) 208-16, 1953. 429. Hooper, F. C. and

  11. Casimir densities for a boundary in Robertson-Walker spacetime

    Energy Technology Data Exchange (ETDEWEB)

    Saharian, A.A., E-mail: saharian@ictp.i [Department of Physics, Yerevan State University, 1 Alex Manoogian Street, 0025 Yerevan (Armenia); Setare, M.R., E-mail: rezakord@ipm.i [Department of Science of Bijar, University of Kurdistan, Bijar (Iran, Islamic Republic of)

    2010-04-12

    For scalar and electromagnetic fields we evaluate the vacuum expectation value of the energy-momentum tensor induced by a curved boundary in the Robertson-Walker spacetime with negative spatial curvature. In order to generate the vacuum densities we use the conformal relation between the Robertson-Walker and Rindler spacetimes and the corresponding results for a plate moving by uniform proper acceleration through the Fulling-Rindler vacuum. For the general case of the scale factor the vacuum energy-momentum tensor is presented as the sum of the boundary free and boundary induced parts.

  12. Casimir densities for a boundary in Robertson-Walker spacetime

    International Nuclear Information System (INIS)

    Saharian, A.A.; Setare, M.R.

    2010-01-01

    For scalar and electromagnetic fields we evaluate the vacuum expectation value of the energy-momentum tensor induced by a curved boundary in the Robertson-Walker spacetime with negative spatial curvature. In order to generate the vacuum densities we use the conformal relation between the Robertson-Walker and Rindler spacetimes and the corresponding results for a plate moving by uniform proper acceleration through the Fulling-Rindler vacuum. For the general case of the scale factor the vacuum energy-momentum tensor is presented as the sum of the boundary free and boundary induced parts.

  13. Global consequences of a local Casimir force : Adhered cantilever

    NARCIS (Netherlands)

    Svetovoy, V. B.; Melenev, A. E.; Lokhanin, M. V.; Palasantzas, G.

    2017-01-01

    Although stiction is a cumbersome problem for microsystems, it stimulates investigations of surface adhesion. In fact, the shape of an adhered cantilever carries information of the adhesion energy that locks one end to the substrate. We demonstrate here that the system is also sensitive to the

  14. Self assembly of anisotropic particles with critical Casimir forces

    NARCIS (Netherlands)

    Nguyễn, Trúc Anh

    2016-01-01

    Building new materials with structures on the micron and nanoscale presents a grand challenge currently. It requires fine control in the assembly of well-designed building blocks, and understanding of the mechanical, thermodynamic, and opto-electronic properties of the resulting structures. Patchy

  15. Zero-point energy in bag models

    International Nuclear Information System (INIS)

    Milton, K.A.

    1979-01-01

    The zero-point (Casimir) energy of free vector (gluon) fields confined to a spherical cavity (bag) is computed. With a suitable renormalization the result for eight gluons is E = + 0.51/a. This result is substantially larger than that for a spherical shell (where both interior and exterior modes are present), and so affects Johnson's model of the QCD vacuum. It is also smaller than, and of opposite sign to, the value used in bag model phenomenology, so it will have important implications there. 1 figure

  16. Scalar field vacuum expectation value induced by gravitational wave background

    Science.gov (United States)

    Jones, Preston; McDougall, Patrick; Ragsdale, Michael; Singleton, Douglas

    2018-06-01

    We show that a massless scalar field in a gravitational wave background can develop a non-zero vacuum expectation value. We draw comparisons to the generation of a non-zero vacuum expectation value for a scalar field in the Higgs mechanism and with the dynamical Casimir vacuum. We propose that this vacuum expectation value, generated by a gravitational wave, can be connected with particle production from gravitational waves and may have consequences for the early Universe where scalar fields are thought to play an important role.

  17. Dynamical symmetries of the Klein-Gordon equation

    International Nuclear Information System (INIS)

    Zhang Fulin; Chen Jingling

    2009-01-01

    The dynamical symmetries of the two-dimensional Klein-Gordon equations with equal scalar and vector potentials (ESVPs) are studied. The dynamical symmetries are considered in the plane and the sphere, respectively. The generators of the SO(3) group corresponding to the Coulomb potential and the SU(2) group corresponding to the harmonic oscillator potential are derived. Moreover, the generators in the sphere construct the Higgs algebra. With the help of the Casimir operators, the energy levels of the Klein-Gordon systems are yielded naturally

  18. Cheshire Cat scenario in A 3+1 dimensional hybrid chiral bag

    International Nuclear Information System (INIS)

    Francia, M. De; Falomir, H.; Santangelo, E.M.

    1995-07-01

    The total energy in the two-phase chiral bag model is studied, including the contribution due to the bag (Casimir energy plus energy of the valence quarks), as well as the one coming from the Skyrmion in the external sector. A consistent determination of the parameters of the model and the renormalization constants in the energy is performed. The total energy shows an approximate independence with the bag radius (separation limit between the phases), in agreement with the Cheshire Cat Principle. (author). 21 refs, 3 figs

  19. Atom-surface potentials and atom interferometry

    International Nuclear Information System (INIS)

    Babb, J.F.

    1998-01-01

    Long-range atom-surface potentials characterize the physics of many actual systems and are now measurable spectroscopically in deflection of atomic beams in cavities or in reflection of atoms in atomic fountains. For a ground state, spherically symmetric atom the potential varies as -1/R 3 near the wall, where R is the atom-surface distance. For asymptotically large distances the potential is weaker and goes as -1/R 4 due to retardation arising from the finite speed of light. This diminished interaction can also be interpreted as a Casimir effect. The possibility of measuring atom-surface potentials using atomic interferometry is explored. The particular cases studied are the interactions of a ground-state alkali-metal atom and a dielectric or a conducting wall. Accurate descriptions of atom-surface potentials in theories of evanescent-wave atomic mirrors and evanescent wave-guided atoms are also discussed. (author)

  20. On the renormalization of string functionals

    International Nuclear Information System (INIS)

    Dietz, K.; Filk, T.

    1982-09-01

    We investigate analytic renormalization procedures for functional integrals, corresponding to field theories defined on compact manifolds, which arise e.g. from string functionals of the Nambu-Schild-Eguchi type. Although these models belong to the nonrenormalizable class of quantum field theories, we prove finiteness for a rectangular string shape up to three loop level, for circular boundary up to two loop order, and for a variety of graphs in higher order, thus indicating that the result might hold in general. From the explicit calculation of the two loop approximation we extract the first model dependent corrections to the qanti q - potential or the Casimir effect. The importance of dilation transformations for the properties of the renormalization procedure are investigated. We prove that under certain conditions, forced by symmetry properties, the association of finite values to divergent series is unique, independent of the regularization procedure. (orig.)