Radiative Corrections to the Casimir Force and Effective Field Theories
Melnikov, Kirill
2001-07-25
Radiative corrections to the Casimir force between two parallel plates are considered in both scalar field theory of one massless and one massive field and in QED. Full calculations are contrasted with calculations based on employing ''boundary-free'' effective field theories. The difference between two previous results on QED radiative corrections to the Casimir force between two parallel plates is clarified and the low-energy effective field theory for the Casimir effect in QED is constructed.
Radiative corrections to the Casimir force and effective field theories
Melnikov, Kirill
2001-08-15
Radiative corrections to the Casimir force between two parallel plates are considered in both scalar field theory of one massless and one massive field and in QED. Full calculations are contrasted with calculations based on employing 'boundary-free' effective field theories. The difference between two previous results on QED radiative corrections to the Casimir force between two parallel plates is clarified and the low-energy effective field theory for the Casimir effect in QED is constructed.
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
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.)
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.
Radiation Pressure Approach to the Repulsive Casimir Force
Hushwater, V.
1999-01-01
We study the Casimir force between a perfectly conducting and an infinitely permeable plate with the radiation pressure approach. This method illustrates how a repulsive force arises as a consequence of the redistribution of the vacuum-field modes corresponding to specific boundary conditions. We discuss also how the method of the zero-point radiation pressure follows from QED.
Evanescent radiation, quantum mechanics and the Casimir effect
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.
Casimir effect and radiative heat transfer between Chern Insulators
Rodriguez Lopez, Pablo; Grushin, Adolfo; Tse, Wang-Kong; Dalvit, Diego
2015-03-01
Chern Insulators are a class of two-dimensional topological materials. Their electronic properties are different from conventional materials, and lead to interesting new physics as quantum Hall effect in absence of an external magnetic field. Here we will review some of their special properties and, in particular, we will discuss the radiative heat transfer and the Casimir effect between two planar Chern Insulators sheets. Finally, we will see how to control the intensity and sign of this Casimir force and the requirements to observe a repulsive Casimir force in the lab with those materials. The research leading to these results has received funding from the People Programme (Marie Curie Actions) of the European Union's Seventh Framework Programme (FP7/2007-2013) under REA Grant Agreement No. 302005.
Fosco, César D
2015-01-01
We study the properties of the classical electromagnetic (EM) radiation produced by two phys- ically different yet closely related systems, which may be regarded as classical analogues of the Dynamical Casimir Effect (DCE). They correspond to two flat, infinite, parallel planes, one of them static and imposing perfect conductor boundary conditions, while the other performs a rigid oscil- latory 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 i...
Thermal correction to the Casimir force, radiative heat transfer, and an experiment
Bezerra, V.B.; Romero, C. [Federal University of Paraiba, Department of Physics, C.P. 5008, Joao Pessoa (Brazil); Bimonte, G. [Universita di Napoli Federico II, Complesso Universitario MSA, Dipartimento di Scienze Fisiche, Napoli (Italy); INFN, Sezione di Napoli, Napoli (Italy); Klimchitskaya, G.L.; Mostepanenko, V.M. [Leipzig University, Center of Theoretical Studies and Institute for Theoretical Physics, Leipzig (Germany)
2007-11-15
The low-temperature asymptotic expressions for the Casimir interaction between two real metals described by the Leontovich surface impedance are obtained in the framework of thermal quantum field theory. It is shown that the Casimir entropy computed using the impedance of infrared optics vanishes in the limit of zero temperature. By contrast, the Casimir entropy computed using the impedance of the Drude model attains at zero temperature a positive value, which depends on the parameters of a system, i.e., the Nernst heat theorem is violated. Thus, the impedance of infrared optics withstands the thermodynamic test, whereas the impedance of the Drude model does not. We also perform a phenomenological analysis of the thermal Casimir force and of the radiative heat transfer through a vacuum gap between real metal plates. The characterization of a metal by means of the Leontovich impedance of the Drude model is shown to be inconsistent with experiment at separations of a few hundred nanometers. A modification of the impedance of infrared optics is suggested taking into account relaxation processes. The power of radiative heat transfer predicted from this impedance is several times less than previous predictions, due to different contributions from the transverse electric evanescent waves. The physical meaning of low frequencies in the Lifshitz formula is discussed. It is concluded that new measurements of radiative heat transfer are required to find the adequate description of a metal in the theory of electromagnetic fluctuations. (orig.)
Small object limit of the Casimir effect and the sign of the Casimir force
We suggest a simple derivation of the Casimir-Polder interaction, and present some general arguments on the finiteness and sign of mutual Casimir interactions. Finally we derive a simple expression for Casimir radiation from small accelerated objects
Small object limit of Casimir effect and the sign of the Casimir force
Kenneth, O.; Nussinov, S.
1999-01-01
We show a simple way of deriving the Casimir Polder interaction, present some general arguments on the finiteness and sign of mutual Casimir interactions and finally we derive a simple expression for Casimir radiation from small accelerated objects.
Esquivel-Sirvent, Raul
Thermally induced electromagnetic fields give rise to the Casimir force and the near field heat transfer between two bodies separated by a gap. These phenomena are described by Rytova's theory of fluctuating electromagnetic fields and both the Casimir force and the near field heat transfer depend on the local dielectric function of the bodies. In this work we present a theoretical calculation on the modulation of fluctuation-induced interactions in the presence of an external magnetic field. The system consists of two parallel plates separated by a gap d. Each plate is isotropic and has a local dielectric function. Applying an external magnetic field parallel to the plates, in the so called Voigt configuration, the plates become anisotropic. In particular, we consider plates of InSb. For the Casimir force the two plates are kept at the same temperature and the external field reduces the magnitude of the force. Similarly if the two plates are kept at different temperature the near field radiative heat transfer is modulated by the magnitude of the external magnetic field. The results are extended to semiconducting quantum wells. In both cases, the excitation of magnetoplasmons provides an explanation for the observed effect.
Radiative dark-bright instability and the critical Casimir effect in DQW exciton condensates
Hakioğlu, T.; Özgün, Ege
2011-07-01
It is already well known that radiative interband interaction in the excitonic normal liquid in semiconducting double quantum wells is responsible for a negligible splitting between the energies of the dark and bright excitons enabling us to consider a four fold spin degeneracy. This has also lead many workers to naively consider the same degeneracy in studying the condensate. On the other hand, the non-perturbative aspects of this interaction in the condensed phase, e.g. its consequences on the order parameter and the dark-bright mixture in the ground state have not been explored. In this work, we demonstrate that the ground state concentrations of the dark and the bright exciton condensates are dramatically different beyond a sharp interband coupling threshold where the contribution of the bright component in the ground state vanishes. This shows that the effect of the radiative interband interaction on the condensate is nonperturbative. We also observe in the free energy a discontinuous derivative with respect to the layer separation at the entrance to the condensed phase, indicating a strong critical Casimir force. An estimate of its strength shows that it is measurable. Measuring the Casimir force is challenging, but at the same time it has a conclusive power about the presence of the long sought for condensed phase.
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)
Radiation Tests of the VELO ECS and Analogue Repeater Mezzanines
Eklund, L; Van der Gracht, A; Vollhardt, A
2006-01-01
The VELO front-end control system and analogue link is based on commercial components where the radiation tolerance is assured by a radiation qualification procedure. This note reports on the radiation qualification of the components required for the VELO ECS mezzanine and analogue repeater mezzanines. They are located at the VELO vacuum vessel where the expected maximal dose is 73 kRad during 10 years of operation. The qualification was done by irradiating prototype circuits at the Paul Scherrer Institut in Villigen, Switzerland. The ECS mezzanine prototypes were irradiated to a dose of 780 kRad and the analogue driver test channels were irradiated to a dose of 600 kRad. All devices were fully functional after the irradiation and only a small increase in current consumption was observed.
The theory of Hawking radiation in laboratory analogues
Robertson, Scott
2015-01-01
Hawking radiation, despite being known to theoretical physics for nearly forty years, remains elusive and undetected. It also suffers, in its original context of gravitational black holes, from practical and conceptual difficulties. Of particular note is the trans-Planckian problem, which is concerned with the apparent origin of the radiation in absurdly high frequencies. In order to gain better theoretical understanding and, it is hoped, experimental verification of Hawking radiation, much study is being devoted to laboratory systems which use moving media to model the spacetime geometry of black holes, and which, by analogy, are also thought to emit Hawking radiation. These analogue systems typically exhibit dispersion, which regularizes the wave behaviour at the horizon at the cost of a more complicated theoretical framework. This tutorial serves as an introduction to Hawking radiation and its analogues, developing the moving medium analogy for black holes and demonstrating how dispersion can be incorporat...
Ruling out stray thermal radiation in analogue black holes
Doukas, Jason; Adesso, Gerardo; Fuentes, Ivette
2014-01-01
Experimental searches for the thermal radiation from analogue black holes require the measurement of very low temperatures in regimes where other thermal noises may interfere or even mimic the sought-after effect. In this letter, we parameterize the family of bosonic thermal channels which give rise to such thermal effects and show that by use of coherent states and homodyne detection one can rule out the non-Hawking contributions and identify those candidate sources which arise from Hawking-...
Stimulated emission and Hawking radiation in black hole analogues
Belgiorno, F
2016-01-01
Stimulated emission by black holes is discussed in light of the analogue gravity program. We first consider initial quantum states containing a definite number of particles, and then we take into account the case where the initial state is a coherent state. The latter case is particularly significant in the case where Hawking radiation is studied in dielectric black holes, and the emission is stimulated by a laser probe. We are particularly interested in the case of the electromagnetic field, for which stimulated radiation is calculated too.
Brevik, Iver [Department of Energy and Process Engineering, Norwegian University of Science and Technology, N-7491 Trondheim (Norway); Romeo, August [Societat Catalana de Fisica, Barcelona, Catalonia (Spain)
2007-07-15
We study the Casimir pressure for a dielectric-diamagnetic cylinder subject to light velocity conservation and with a dispersion law analogous to Sellmeir's rule. Similarities to and differences from the spherical case are pointed out.
Casimir Effect - The Classical Limit
The temperature dependence of the Casimir effect for the radiation field confined between two conducting plates is analysed; The Casimir energy is shown to decline exponentially with temperature while the Casimir entropy which is defined in the text is shown to approach a limit which depends only on the geometry of the constraining plates. The result is shown to hold, for a scalar field, for arbitrary geometry. The high temperature (T) expansion is shown to be ''robust'', i.e. it does not have any nonvanishing correction to the ''classical' result where the latter is defined by the validity of the Rayleigh - Jeans law. We show that validity of the Rayleigh - Jeans law implies the vanishing of the Casimir energy, hence the high temperature Casimir force, for a wide variety of geometries, is purely entropic
Classical aspects of Hawking radiation verified in analogue gravity experiment
Weinfurtner, Silke; Penrice, Matthew C J; Unruh, William G; Lawrenc, Gregory A
2013-01-01
There is an analogy between the propagation of fields on a curved spacetime and shallow water waves in an open channel flow. By placing a streamlined obstacle into an open channel flow we create a region of high velocity over the obstacle that can include wave horizons. Long (shallow water) waves propagating upstream towards this region are blocked and converted into short (deep water) waves. This is the analogue of the stimulated Hawking emission by a white hole (the time inverse of a black hole). The measurements of amplitudes of the converted waves demonstrate that they appear in pairs and are classically correlated; the spectra of the conversion process is described by a Boltzmann-distribution; and the Boltzmann-distribution is determined by the determined by the change in flow across the white hole horizon.
A natural composite material, hydroxyapatite (HA) and high density polyethylene (HDPE) crosslinked by ionizing radiations is been developed as a bioactive analogue material for bone replacement. Mechanical properties of the composites irradiated up to 300 kGy under tensile tests was studied. Gel content and micrographs of different composite fractures are shown. (author)
We discuss repulsive Casimir forces between dielectric materials with nontrivial magnetic susceptibility. It is shown that considerations based on the naive pairwise summation of van der Waals and Casimir-Polder forces may not only give an incorrect estimate of the magnitude of the total Casimir force but even the wrong sign of the force when materials with high dielectric and magnetic responses are involved. Indeed repulsive Casimir forces may be found in a large range of parameters, and we suggest that the effect may be realized in known materials. The phenomenon of repulsive Casimir forces may be of importance both for experimental study and for nanomachinery applications
Repulsive Casimir and Casimir-Polder Forces
Milton, Kimball A; Parashar, Prachi; Pourtolami, Nima; Brevik, Iver; Ellingsen, Simen A
2012-01-01
Casimir and Casimir-Polder repulsion 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 recent developments will be reviewed. Here, stress will be placed on analytic developments, especially of Casimir-Polder (CP) interactions between anisotropically polarizable atoms, and CP interactions between anisotropic atoms and bodies that also exhibit anisotropy, ...
Casimir self-energy of a free electron
Rosencwaig, Allan
2006-01-01
We derive the electromagnetic self-energy and the radiative correction to the gyromagnetic ratio of a free electron using a Casimir energy approach. This method provides an attractive and straightforward physical basis for the renormalization process.
Critical Casimir forces for colloidal assembly
Critical Casimir forces attract increasing interest due to their opportunities for reversible particle assembly in soft matter and nano science. These forces provide a thermodynamic analogue of the celebrated quantum mechanical Casimir force that arises from the confinement of vacuum fluctuations of the electromagnetic field. In its thermodynamic analogue, solvent fluctuations, confined between suspended particles, give rise to an attractive or repulsive force between the particles. Due to its unique temperature dependence, this effect allows in situ control of reversible assembly. Both the force magnitude and range vary with the solvent correlation length in a universal manner, adjusting with temperature from fractions of the thermal energy, k B T, and nanometre range to several ten kT and micrometer length scale. Combined with recent breakthroughs in the synthesis of complex particles, critical Casimir forces promise the design and assembly of complex colloidal structures, for fundamental studies of equilibrium and out-of-equilibrium phase behaviour. This review highlights recent developments in this evolving field, with special emphasis on the dynamic interaction control to assemble colloidal structures, in and out of equilibrium. (topical review)
Critical Casimir forces for colloidal assembly
Nguyen, V. D.; Dang, M. T.; Nguyen, T. A.; Schall, P.
2016-02-01
Critical Casimir forces attract increasing interest due to their opportunities for reversible particle assembly in soft matter and nano science. These forces provide a thermodynamic analogue of the celebrated quantum mechanical Casimir force that arises from the confinement of vacuum fluctuations of the electromagnetic field. In its thermodynamic analogue, solvent fluctuations, confined between suspended particles, give rise to an attractive or repulsive force between the particles. Due to its unique temperature dependence, this effect allows in situ control of reversible assembly. Both the force magnitude and range vary with the solvent correlation length in a universal manner, adjusting with temperature from fractions of the thermal energy, k B T, and nanometre range to several ten kT and micrometer length scale. Combined with recent breakthroughs in the synthesis of complex particles, critical Casimir forces promise the design and assembly of complex colloidal structures, for fundamental studies of equilibrium and out-of-equilibrium phase behaviour. This review highlights recent developments in this evolving field, with special emphasis on the dynamic interaction control to assemble colloidal structures, in and out of equilibrium.
de Nova, J R M
2015-01-01
The work is divided in three parts. We devote the first part to the study of analog Hawking radiation in Bose-Einstein condensates. We study numerically the birth of a sonic black hole in an outcoupled Bose-Einstein condensate after relaxing the confinement provided by an optical lattice. We also study possible signatures of spontaneous Hawking radiation. We propose that the violation of CS inequalities is a smoking gun of the presence of the Hawking effect. We compare this criterion with the presence of entaglement, finding that both are equivalent under usual assumptions. Finally, we study a different gravitational analogue: the so-called black-hole laser. The most interesting result is the appearance of a regime of continuous and periodic emission of solitons, providing the most strong analogue with optical lasers. In the second part, we analyze the effect of the introduction of a short Bragg pulse in a thermal cloud. We show that the induced periodic density pattern decays to the equilibrium profile. Howe...
Tse, Wang-Kong; Macdonald, A. H.
2012-01-01
We investigate the Casimir effect between two-dimensional electron systems driven to the quantum Hall regime by a strong perpendicular magnetic field. In the large separation (d) limit where retardation effects are essential we find i) that the Casimir force is quantized in units of 3\\hbar c \\alpha^2/(8\\pi^2 d^4), and ii) that the force is repulsive for mirrors with same type of carrier, and attractive for mirrors with opposite types of carrier. The sign of the Casimir force is therefore elec...
Modification of radiation-induced division delay by caffeine analogues and dibutyryl cyclic AMP
The mitotic selection procedure for cell cycle analysis was utilized to investigate the concentration-dependent modification of x-radiation-induced division delay in Chinese hamster ovary (CHO) cells by methyl xanthines (caffeine, theophylline, and theobromine) and by dibutyryl cyclic AMP. The methyl xanthines (concentrations from 0.5 to 1000 μg/ml) all reduced radiation-induced division delay with the effect being linear between approximately 100 and 1000 μg/ml. After doses of 100-300 rad, delay was reduced by 75, 94 or 83 per cent at 1000 μg/ml for each drug, respectively. However, the addition of dibutyryl cyclic AMP had an opposite effect: radiation-induced delay was increased by the concentration range of 0.3 to 300 μg/ml. These results indicate that in mammalian cells the control of cell cycle progression and the modification of radiation-induced division delay are not simply related to intracellular levels of cyclic AMP. Rather, there appear to be at least two competing mechanisms which are differentially affected by caffeine analogues or by direct addition of dibutyryl cyclic AMP. The direct effect of caffeine and the methyl xanthines on membrane calcium permeability is considered. (author)
Nieto-Vesperinas, Manuel
2014-01-01
The mechanical action on matter of the electromagnetic field emitted by a fluctuating source is governed by its statistics. In particular, thermal sources and vacuum fluctuations exert on bodies those well-known Casimir (C) and Van der Waals (VdW) forces. However, we have recently demonstrated that partially coherent random electromagnetic fields emitted by tailored optical sources, induce a photonic force on particles which, in particular, may be equivalent to those of Van der Waals and Casimir.
The radiation chemistry of Hoechst 33258 and its potential radiosensitizing analogues
Nel, P. [Melbourne Univ., Parkville, VIC (Australia). Dept. of Chemistry]|[Peter McCallum Cancer Institute, Reserach Division, East Melbourne, VIC (Australia); Cooper, R. [Melbourne Univ., Parkville, VIC (Australia). Dept. of Chemistry; Martin, R.F. [Peter McCallum Cancer Institute, East Melbourne, VIC, (Australia)
1996-12-31
Collaborative research between Peter MacCallum Cancer Institute and The University of Melbourne is aimed to investigate the photochemistry and radiation chemistry of the halogenated analogues m-I Hoechst and o-I Hoechst (which are being developed as potential radiosensitizers). Studies were conducted on Hoechst 33258, phenyl Hoechst, m-I Hoechst and o-I Hoechst. The chemical interaction between the Hoechst analogues and the radiolysis products of water (the hydroxy radical and the aqueous electron) were investigated by saturating aqueous solutions with nitrogen or nitrous oxide (an electron scavenger) and using 2-propanol as a hydroxy radical scavenger. Hoechst 33258 was investigated at pH 5 and pH 9. Transient absorption spectra of micromolar solutions saturated with nitrogen or nitrous oxide suggest the formation of hydroxyl radical adduct(s). The rate of formation of these transient spectra was observed to be dependent on the concentration of Hoechst 33258. Phenyl Hoechst, m- I Hoechst and o-I Hoechst were studied at pH 5. Spectra again suggest the formation of hydroxy radical adducts and that both m-I Hoechst and o-I Hoechst react with aqueous electrons.
The radiation chemistry of Hoechst 33258 and its potential radiosensitizing analogues
Collaborative research between Peter MacCallum Cancer Institute and The University of Melbourne is aimed to investigate the photochemistry and radiation chemistry of the halogenated analogues m-I Hoechst and o-I Hoechst (which are being developed as potential radiosensitizers). Studies were conducted on Hoechst 33258, phenyl Hoechst, m-I Hoechst and o-I Hoechst. The chemical interaction between the Hoechst analogues and the radiolysis products of water (the hydroxy radical and the aqueous electron) were investigated by saturating aqueous solutions with nitrogen or nitrous oxide (an electron scavenger) and using 2-propanol as a hydroxy radical scavenger. Hoechst 33258 was investigated at pH 5 and pH 9. Transient absorption spectra of micromolar solutions saturated with nitrogen or nitrous oxide suggest the formation of hydroxyl radical adduct(s). The rate of formation of these transient spectra was observed to be dependent on the concentration of Hoechst 33258. Phenyl Hoechst, m- I Hoechst and o-I Hoechst were studied at pH 5. Spectra again suggest the formation of hydroxy radical adducts and that both m-I Hoechst and o-I Hoechst react with aqueous electrons
Tse, Wang-Kong; MacDonald, A H
2012-12-01
We investigate the Casimir effect between two-dimensional electron systems driven to the quantum Hall regime by a strong perpendicular magnetic field. In the large-separation (d) limit where retardation effects are essential, we find (i) that the Casimir force is quantized in units of 3ħcα(2)/8π(2)d(4) and (ii) that the force is repulsive for mirrors with the same type of carrier and attractive for mirrors with opposite types of carrier. The sign of the Casimir force is therefore electrically tunable in ambipolar materials such as graphene. The Casimir force is suppressed when one mirror is a charge-neutral graphene system in a filling factor ν=0 quantum Hall state. PMID:23368242
Nonlinear (Anharmonic Casimir Oscillator
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.
Casimir force for electrolytes
Høye, J. S.
2009-01-01
The Casimir force between a pair of parallell plates filled with ionic particles is considered. We use a statistical mechanical approach and consider the classical high temperature limit. In this limit the ideal metal result with no transverse electric (TE) zero frequency mode is recovered. This result has also been obtained by Jancovici and \\v{S}amaj earlier. Our derivation differs mainly from the latter in the way the Casimir force is evaluated from the correlation function. By our approach...
On convergence generation in computing the electro-magnetic Casimir force
Schuller, F. [Lab. de Physique des Lasers, UMR 7538 du CNRS, Univ. Paris 13, Villetaneuse (France)
2008-09-15
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.)
Klimchitskaya, G. L.; Mohideen, U.; Mostepanenko, V. M.
2007-01-01
Based on the Lifshitz theory we show that the illumination of one (Si) plate in the three-layer systems Au--ethanol--Si, Si--ethanol--Si and $\\alpha$-Al${}_2$O${}_3$--ethanol--Si with laser pulses can change the Casimir attraction to Casimir repulsion and vice versa. The proposed effect opens novel opportunities in nanotechnology to actuate the periodic movement in electro- and optomechanical micromachines based entirely on the zero-point oscillations of the quantum vacuum without the action ...
Klimchitskaya, G L [Center of Theoretical Studies and Institute for Theoretical Physics, Leipzig University, Postfach 100920, D-04009, Leipzig (Germany); Mohideen, U [Department of Physics and Astronomy, University of California, Riverside, CA 92521 (United States); Mostepanenko, V M [Center of Theoretical Studies and Institute for Theoretical Physics, Leipzig University, Postfach 100920, D-04009, Leipzig (Germany)
2007-08-24
Based on the Lifshitz theory we show that the illumination of one (Si) plate in the three-layer systems Au-ethanol-Si, Si-ethanol-Si and {alpha}-Al{sub 2}O{sub 3}-ethanol-Si with laser pulses can change the Casimir attraction to Casimir repulsion and vice versa. The proposed effect opens novel opportunities in nanotechnology to actuate the periodic movement in electro- and optomechanical micromachines based entirely on the zero-point oscillations of the quantum vacuum without the action of mechanical springs. (fast track communication)
Casimir force between partially transmitting mirrors
Jaekel, Marc-Thierry; Reynaud, Serge
2001-01-01
The Casimir force can be understood as resulting from the radiation pressure exerted by the vacuum fluctuations reflected by boundaries. We extend this local formulation to the case of partially transmitting boundaries by introducing reflectivity and transmittivity coefficients obeying conditions of unitarity, causality and high frequency transparency. We show that the divergences associated with the infiniteness of the vacuum energy do not appear in this approach. We give explicit expression...
Radiosensitizing effects of nitroimidazole nucleoside analogues (RK-27, RK-28 and RK-29) were studied using cultured mouse leukemic L5178Y (L5178Y) cells and Chinese hamster V79 (CH V79) cells. There was no significant difference in sensitizer enhancement ratio among the three RK-compounds. The ratios were 1.7 for L5178Y cells and 1.6 for CH V79 cells at 1 mM concentration and were comparable to that of misonidazole. Sensitizer enhancement ratios of RK-28 for L5178Y cells irradiated with 1 to 4 Gy X-rays were, respectively, 1.5 to 1.6 at 0.5 mM concentration, which were nearly the same as those obtained at high doses. RK-28 was as effective for fractionated X-irradiation as for single X-irradiation, assuming complete repair of sublethal damage during incubation at 37degC between sessions of fractionated X-irradiation. The sensitizing effects of RK-28 were additive in combination with neocarzinostatin, an antitumor drug, which has different pharmacological and physiological properties, and enhances the radioresponse of cells. RK-28 is known to be rapidly metabolized and excreted in vivo and is thus expected to be less toxic than misonidazole. It was effective at low radiation doses routinely used in radiotherapy practice and for fractionated X-irradiation, suggesting its clinical utility. (author)
Impact of an angiotensin analogue in treating thermal and combined radiation injuries
Jadhav, Sachin Suresh
Background: In recent years there has been a growing concern regarding the use of nuclear weapons by terrorists. Such incidents in the past have shown that radiation exposure is often accompanied by other forms of trauma such as burns, wounds or infection; leading to increased mortality rates among the affected individuals. This increased risk with combined radiation injury has been attributed to the delayed wound healing observed in this injury. The Renin-Angiotensin System (RAS) has emerged as a critical regulator of wound healing. Angiotensin II (A-II) and Angiotensin (1-7) [A(1-7)] have been shown to accelerate the rate of wound healing in different animal models of cutaneous injury. Nor-Leu3-Angiotensin (1-7) [Nor-Leu3-A (1-7)], an analogue of A(1-7), is more efficient than both A-II and A(1-7) in its ability to improve wound healing and is currently in phase III clinical trials for the treatment of diabetic foot ulcers. Aims: The three main goals of this study were to; 1) Develop a combined radiation and burn injury (CRBI) model and a radiation-induced cutaneous injury model to study the pathophysiological effects of these injuries on dermal wound healing; 2) To treat thermal and CRBI injuries using Nor-Leu 3-A (1-7) and decipher the mechanism of action of this peptide and 3) Develop an in-vitro model of CRBI using dermal cells in order to study the effect of CRBI on individual cell types involved in wound healing. Results: CRBI results in delayed and exacerbated apoptosis, necrosis and inflammation in injured skin as compared to thermal injury by itself. Radiation-induced cutaneous injury shows a radiation-dose dependent increase in inflammation as well as a chronic inflammatory response in the higher radiation exposure groups. Nor-Leu3-A (1-7) can mitigate thermal and CRBI injuries by reducing inflammation, oxidative stress and DNA damage while increasing the rate of proliferation of dermal stem cells and re-epithelialization of injured skin. The in
Casimir Effect The Classical Limit
Feinberg, J; Revzen, M
2001-01-01
We analyze the high temperature limit of the Casimir effect. A simple physical argument suggests that the Casimir energy (as opposed to the Casimir free energy) should vanish in the classical limit. We check the validity of this argument for massless scalar field confined in a cavity with boundaries of arbitrary shape, using path integral formalism. We are able to verify this suggestion only when the boundaries consist of disjoint pieces. Moreover, we find in these cases that the contribution to the Casimir entropy by field modes that depend on that separation, tends, in the classical limit, to a finite asymptotic value which depends only on the geometry of the cavity. 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 arbitrary geometry of the cavity. Contributions to the Casimir thermodynamical quantities due to each individual connected component of the boundary exhibit logarithmic deviations i...
Is repulsive Casimir force physical?
Cho, Sung Nae
2004-01-01
The Casimir force for charge-neutral, perfect conductors of non-planar geometric configurations have been investigated. The configurations are: (1) the plate-hemisphere, (2) the hemisphere-hemisphere and (3) the spherical shell. The resulting Casimir forces for these physical arrangements have been found to be attractive. The repulsive Casimir force found by Boyer for a spherical shell is a special case requiring stringent material property of the sphere, as well as the specific boundary cond...
Casimir force in absorbing multilayers
Tomas, M. S.
2002-01-01
The Casimir effect in a dispersive and absorbing multilayered system is considered adopting the (net) vacuum-field pressure point of view to the Casimir force. Using the properties of the macroscopic field operators appropriate for absorbing systems and a convenient compact form of the Green function for a multilayer, a straightforward and transparent derivation of the Casimir force in a lossless layer of an otherwise absorbing multilayer is presented. The resulting expression in terms of the...
Casimir force between metallic mirrors
Lambrecht, Astrid; Reynaud, Serge
1999-01-01
We study the influence of finite conductivity of metals on the Casimir effect. We put the emphasis on explicit theoretical evaluations which can help comparing experimental results with theory. The reduction of the Casimir force is evaluated for plane metallic plates. The reduction of the Casimir energy in the same configuration is also calculated. It can be used to infer the reduction of the force in the plane-sphere geometry through the `proximity theorem'. Frequency dependent dielectric re...
Thermodynamics of the Casimir Effect Asymptotic Considerations
Mitter, H
1998-01-01
We study the Casimir effect with different temperatures between the plates ($T$) resp. outside of them ($T'$). If we consider the inner system as the black body radiation for a special geometry, then contrary to common belief the temperature approaches a constant value for vanishing volume during isentropic processes. This means: the reduction of the degrees of freedom can not be compensated by a concentration of the energy during an adiabatic contraction of the two-plate system. Looking at the Casimir pressure, we find one unstable equilibrium point for isothermal processes with $T > T'$. For isentropic processes there is additionally one stable equilibrium point for larger values of the distances between the two plates.}
Dartnell, L. R.
2016-05-01
Here we discuss the use of Raman and FTIR spectroscopy for the detection and characterisation of biosignatures in martian analogue samples, and their degradation by the cosmic ray environment in the martian near-subsurface.
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
Emig, Thorsten
2007-01-01
We explore the non-linear dynamics of two parallel periodically patterned metal surfaces that are coupled by the zero-point fluctuations of the electromagnetic field between them. The resulting Casimir force generates for asymmetric patterns with a time-periodically driven surface-to-surface distance a ratchet effect, allowing for directed lateral motion of the surfaces in sizeable parameter ranges. It is crucial to take into account inertia effects and hence chaotic dynamics which are descri...
Fateev, Evgeny G.
2012-01-01
The possibility in principle is shown that the noncompensated Casimir force can exist in nanosized open metal cavities. The force shows up as time-constant expulsion of open cavities toward their least opening. The optimal parameters of the angles of the opening, of "generating lines" of cavities and their lengths are found at which the expulsive force is maximal. The theory is created for trapezoid configurations, in particular for parallel mirrors which experience both the transverse Casimi...
Jaekel, Marc-Thierry; Reynaud, Serge
2001-01-01
We study the situation where two point like mirrors are placed in the vacuum state of a scalar field in a two-dimensional spacetime. Describing the scattering upon the mirrors by transmittivity and reflectivity functions obeying unitarity, causality and high frequency transparency conditions, we compute the fluctuations of the Casimir forces exerted upon the two motionless mirrors. We use the linear response theory to derive the motional forces exerted upon one mirror when it moves or when th...
Casimir effect: The classical limit
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
Casimir Effect : Theory and Experiments
Lambrecht, Astrid
2011-01-01
The Casimir effect is a crucial prediction of Quantum Field Theory which has fascinating connections with open questions in fundamental physics. The ideal formula written by Casimir does not describe real experiments and it has to be generalized by taking into account the effects of imperfect reflection, thermal fluctuations, geometry as well as the corrections coming from surface physics. We discuss these developments in Casimir physics and give the current status in the comparison between theory and experiment after years of improvements in measurements as well as theory.
Casimir force between liquid metals
Esquivel-Sirvent, R.; Escobar, J. V.
2014-08-01
We present a theoretical calculation of the Casimir force between liquid metals at room temperature using as case studies mercury (Hg) and eutectic indium gallium (EInGa). The surface tension of the liquids creates surfaces of zero roughness that are truly equipotential, an ideal characteristic for Casimir force experiments. As we show the dielectric properties of Au, EInGa and Hg are very similar and the difference on the Casimir force between Au and EInGa and Au and Hg is less than 4%. Based on these results, a modification of the IUPUI experiment for detecting deviations of Newtonian gravity is proposed.
Casimir force on amplifying bodies
Sambale, Agnes; Welsch, Dirk-Gunnar; Buhmann, Stefan Yoshi; Dung, Ho Trung
2009-01-01
Based on a unified approach to macroscopic QED that allows for the inclusion of amplification in a limited space and frequency range, we study the Casimir force as a Lorentz force on an arbitrary partially amplifying system of linearly locally responding (isotropic) magnetoelectric bodies. We demonstrate that the force on a weakly polarisable/magnetisable amplifying object in the presence of a purely absorbing environment can be expressed as a sum over the Casimir--Polder forces on the excite...
Casimir force between bimetallic heterostructures
Barcenas, J.; Reyes, L.; Esquivel Sirvent, R. [Instituto de Fisica, Universidad Nacional Autonoma de Mexico, Apartado Postal 20-364 Ciudad Universitaria, Mexico, 01000 (Mexico)
2005-05-01
We present a general method for calculating the Casimir force between heterostructures using an effective surface impedance approach. Within this formalism we study the effect of thin film coatings on the force. As a case study we present results for a system made of alternate layers of Mg and Ni and evaluate the effect that Pd coatings have on the Casimir force. (copyright 2005 WILEY-VCH Verlag GmbH and Co. KGaA, Weinheim) (orig.)
Casimir force between eccentric cylinders
Dalvit, Diego A. R.; Lombardo, Fernando C.; Mazzitelli, Francisco D.; Onofrio, Roberto
2004-01-01
We consider the Casimir interaction between a cylinder and a hollow cylinder, both conducting, with parallel axis and slightly different radii. The Casimir force, which vanishes in the coaxial situation, is evaluated for both small and large eccentricities using the proximity approximation. The cylindrical configuration offers various experimental advantages with respect to the parallel planes or the plane-sphere geometries, leading to favourable conditions for the search of extra-gravitation...
Repulsive Casimir Force: Sufficient Conditions
Rosa, Luigi; Lambrecht, Astrid
2010-01-01
In this paper the Casimir energy of two parallel plates made by materials of different penetration depth and no medium in between is derived. We study the Casimir force density and derive analytical constraints on the two penetration depths which are sufficient conditions to ensure repulsion. Compared to other methods our approach needs no specific model for dielectric or magnetic material properties and constitutes a complementary analysis.
Flachi, Antonino
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, loca...
Enhanced Casimir effect for doped graphene
Bordag, M.; Fialkovskiy, I.; Vassilevich, D.
2016-02-01
We analyze the Casimir interaction of doped graphene. To this end we derive a simple expression for the finite-temperature polarization tensor with a chemical potential. It is found that doping leads to a strong enhancement of the Casimir force, reaching almost 60 % in quite realistic situations. This result should be important for planning and interpreting Casimir measurements, especially taking into account that the Casimir interaction of undoped graphene is rather weak.
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 regularisation, the vacuum energy of the arrangement is finite for conformal propagation in space-time. 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 attracted or repelled 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.
Cells of the bacterium Mycoplasma mycoides var. capri grown in a medium containing the potential radiation-sensitive thymine analogue 5-vinyluracil show a 3-fold increase in sensitivity towards irradiation of a dose of 15 krads of γ-rays. (author)
Casimir Force for Absorbing Media in an Open Quantum System Framework: Scalar Model
Lombardo, Fernando C; Lopez, Adrian E Rubio
2011-01-01
In this article we compute the Casimir force between two finite-width mirrors at finite temperature, working in a simplified model in 1+1 dimensions. The mirrors, considered as dissipative media, are modeled by a continuous set of harmonic oscillators which in turn are coupled to an external environment at thermal equilibrium. The calculation of the Casimir force is performed in the framework of the theory of quantum open systems. It is shown that the Casimir interaction has two different contributions: the usual radiation pressure from vacuum, which is obtained for ideal mirrors without dissipation or losses, and a Langevin force associated with the noise induced by the interaction between dielectric atoms in the slabs and the thermal bath. Both contributions to the Casimir force are needed in order to reproduce the analogous of Lifshitz formula in 1+1 dimensions. We also discuss the relation between the electromagnetic properties of the mirrors and the spectral density of the environment
Casimir force for absorbing media in an open quantum system framework: Scalar model
Lombardo, Fernando C.; Rubio Lopez, Adrian E. [Departamento de Fisica Juan Jose Giambiagi, FCEyN UBA and IFIBA CONICET, Facultad de Ciencias Exactas y Naturales, Ciudad Universitaria, Pabellon I, 1428 Buenos Aires (Argentina); Mazzitelli, Francisco D. [Departamento de Fisica Juan Jose Giambiagi, FCEyN UBA and IFIBA CONICET, Facultad de Ciencias Exactas y Naturales, Ciudad Universitaria, Pabellon I, 1428 Buenos Aires (Argentina); Centro Atomico Bariloche Comision Nacional de Energia Atomica, R8402AGP Bariloche (Argentina)
2011-11-15
In this article we compute the Casimir force between two finite-width mirrors at finite temperature, working in a simplified model in 1+1 dimensions. The mirrors, considered as dissipative media, are modeled by a continuous set of harmonic oscillators which in turn are coupled to an external environment at thermal equilibrium. The calculation of the Casimir force is performed in the framework of the theory of open quantum systems. It is shown that the Casimir interaction has two different contributions: the usual radiation pressure from the vacuum, which is obtained for ideal mirrors without dissipation or losses, and a Langevin force associated with the noise induced by the interaction between dielectric atoms in the slabs and the thermal bath. Both contributions to the Casimir force are needed in order to reproduce the analogous Lifshitz formula in 1+1 dimensions. We also discuss the relationship between the electromagnetic properties of the mirrors and the spectral density of the environment.
Schwinger's Dynamical Casimir Effect Bulk Energy Contribution
Carlson, C E; Pérez-Mercader, J; Visser, M; Carlson, C E; Carlson, Carl E.; Molina-Paris, Carmen; Perez-Mercader, Juan; Visser, Matt
1997-01-01
Schwinger's Dynamical Casimir Effect is one of several candidate explanations for sonoluminescence. Recently, several papers have claimed that Schwinger's estimate of the Casimir energy involved is grossly inaccurate. In this letter, we show that these calculations omit the crucial volume term. When the missing term is correctly included one finds full agreement with Schwinger's result for the Dynamical Casimir Effect. We have nothing new to say about sonoluminescence itself except to affirm that the Casimir effect is energetically adequate as a candidate explanation. Schwinger's Dynamical Casimir Effect is one of several candidate explanations for sonoluminescence. Recently, several papers have claimed that Schwinger's estimate of the Casimir energy involved is grossly inaccurate. In this letter, we show that these calculations omit the crucial volume term. When the missing term is correctly included one finds full agreement with Schwinger's result for the Dynamical Casimir Effect. We have nothing new to say...
Negative Entropies in Casimir and Casimir-Polder Interactions
Milton, Kimball A; Kalauni, Pushpa; Parashar, Prachi; Guérout, Romain; Ingold, Gert-Ludwig; Lambrecht, Astrid; Reynaud, Serge
2016-01-01
It has been increasingly becoming clear that Casimir and Casimir-Polder entropies may be negative in certain regions of temperature and separation. In fact, the occurrence of negative entropy seems to be a nearly ubiquitous phenomenon. This is most highlighted in the quantum vacuum interaction of a nanoparticle with a conducting plate or between two nanoparticles. It has been argued that this phenomenon does not violate physical intuition, since the total entropy, including the self-entropies of the plate and the nanoparticle, should be positive. New calculations, in fact, seem to bear this out at least in certain cases.
Stochastic Quantization and Casimir Forces
Rodriguez-Lopez, Pablo; Soto, Rodrigo
2011-01-01
In this paper we show how the stochastic quantization method developed by Parisi and Wu can be used to obtain Casimir forces. Both quantum and thermal fluctuations are taken into account by a Langevin equation for the field. The method allows the Casimir force to be obtained directly, derived from the stress tensor instead of the free energy. It only requires the spectral decomposition of the Laplacian operator in the given geometry. The formalism provides also an expression for the fluctuations of the force. As an application we compute the Casimir force on the plates of a finite piston of arbitrary cross section. Fluctuations of the force are also directly obtained, and it is shown that, in the piston case, the variance of the force is twice the force squared.
Muñoz de Nova, Juan Ramón
2015-01-01
The work is divided in three parts. We devote the first part to the study of analog Hawking radiation in Bose-Einstein condensates. We study numerically the birth of a sonic black hole in an outcoupled Bose-Einstein condensate after relaxing the confinement provided by an optical lattice. We also study possible signatures of spontaneous Hawking radiation. We propose that the violation of CS inequalities is a smoking gun of the presence of the Hawking effect. We compare this criterion with the...
Comment on Repulsive Casimir Forces
Iannuzzi, D
2003-01-01
A recent theoretical calculation shows that the Casimir force between two parallel plates can be repulsive for plates with nontrivial magnetic properties (O. Kenneth et al., Phys. Rev. Lett. 89, 033001 (2002)). According to the authors, the effect may be observed with known materials, such as ferrites and garnets, and it might be possible to engineer micro- or nanoelectromechanical systems (MEMS or NEMS) that could take advantage of a short range repulsive force. Here we show that on the contrary the Casimir force between two parallel plates in vacuum at micron and submicron distance is always attractive.
Cavalcanti, R. M.
2003-01-01
We consider a massless scalar field obeying Dirichlet boundary conditions on the walls of a two-dimensional L x b rectangular box, divided by a movable partition (piston) into two compartments of dimensions a x b and (L-a) x b. We compute the Casimir force on the piston in the limit L -> infinity. Regardless of the value of a/b, the piston is attracted to the nearest end of the box. Asymptotic expressions for the Casimir force on the piston are derived for a > b.
Archimedes Force on Casimir Apparatus
Shevchenko, Vladimir
2016-01-01
We address a problem of Casimir apparatus in dense medium and weak gravitational field. The falling of the apparatus has to be governed by the equivalence principle, with proper account for contributions to the weight of the apparatus from its material part and from distorted quantum fields. We discuss general expression for the corresponding force in metric with cylindrical symmetry. By way of example we compute explicit expression for Archimedes force, acting on the Casimir apparatus of finite size, immersed into thermal bath of free scalar field. It is shown that besides universal term, proportional to the volume of the apparatus, there are non-universal quantum corrections, depending on the boundary conditions.
As the technological advances lead to miniaturization of mechanical devices, engineers face new challenges that are brought about by the fundamentally different rules that apply at small scales. One of the biggest problems in small machines is the excessive wear of the many surfaces that work in contact with each other, which severely constrains the durability of such machine parts. Here, a force that is caused by the quantum fluctuations of electromagnetic field- known as the lateral Casimir force-is employed to propose a design for a potentially wear-proof rack and pinion with no contact, which can be miniaturized to nano-scale. We demonstrate that both uniform and harmonic lateral motion of the rack can be converted into unidirectional rotation of the pinion. The robustness of the design is studied by exploring the relation between the pinion velocity and the rack velocity in the different domains of the parameter space. The effects of friction and added external load are also examined
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.
Casimir-Lifshitz force out of thermal equilibrium
Antezza, M; Pitaevskii, L. P.; Stringari, S.; Svetovoy, V.
2007-01-01
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 coming from the propagating and evanescent components of the electromagnetic radiation is performed. The large distance behaviors of such interactions is discussed, and both analytical and numerical res...
Casimir force between dispersive magnetodielectrics
Tomas, M.S. [Rudjer Boskovic Institute, P.O. Box 180, 10002 Zagreb (Croatia)]. E-mail: tomas@thphys.irb.hr
2005-07-25
We extend our approach to the Casimir effect between absorbing dielectric multilayers [M.S. Tomas, Phys. Rev. A 66 (2002) 052103] to magnetodielectric systems. The resulting expression for the force is used to numerically explore the effect of the medium dispersion on the attractive/repulsive force in a metal-magnetodielectric system described by the Drude-Lorentz permittivities and permeabilities.
Casimir force between dispersive magnetodielectrics
Tomas, M. S.
2004-01-01
We extend our approach to the Casimir effect between absorbing dielectric multilayers [M. S. Tomas, Phys. Rev. A 66, 052103 (2002)] to magnetodielectric systems. The resulting expression for the force is used to numerically explore the effect of the medium dispersion on the attractive/repulsive force in a metal-magnetodielectric system described by the Drude-Lorentz permittivities and permeabilities.
Synchrotron-Radiation X-Ray Investigation of Li+/Na+ Intercalation into Prussian Blue Analogues
Yutaka Moritomo
2013-01-01
Full Text Available Prussian blue analogies (PBAs are promising cathode materials for lithium ion (LIB and sodium ion (SIB secondary batteries, reflecting their covalent and nanoporous host structure. With use of synchrotron-radiation (SR X-ray source, we investigated the structural and electronic responses of the host framework of PBAs against Li+ and Na+ intercalation by means of the X-ray powder diffraction (XRD and X-ray absorption spectroscopy (XAS. The structural investigation reveals a robust nature of the host framework against Li+ and Na+ intercalation, which is advantageous for the stability and lifetime of the batteries. The spectroscopic investigation identifies the redox processes in respective plateaus in the discharge curves. We further compare these characteristics with those of the conventional cathode materials, such as, LiCoO2, LiFePO4, and LiMn2O4.
Experiment and theory in the Casimir effect
Klimchitskaya, G L
2006-01-01
Casimir effect is the attractive force which acts between two plane parallel, closely spaced, uncharged, metallic plates in vacuum. This phenomenon was predicted theoretically in 1948 and reliably investigated experimentally only in recent years. In fact, the Casimir force is similar to the familiar van der Waals force in the case of relatively large separations when the relativistic effects come into play. We review the most important experiments on measuring the Casimir force by means of torsion pendulum, atomic force microscope and micromechanical torsional oscillator. Special attention is paid to the puzzle of the thermal Casimir force, i.e., to the apparent violation of the third law of thermodynamics when the Lifshitz theory of dispersion forces is applied to real metals. Thereafter we discuss the role of the Casimir force in nanosystems including the stiction phenomenon, actuators, and interaction of hydrogen atoms with carbon nanotubes. The applications of the Casimir effect for constraining predictio...
Schwinger's Dynamical Casimir Effect: Bulk Energy Contribution
Carlson, Carl E.; Molina--Paris, Carmen; Perez--Mercader, Juan; Visser, Matt(School of Mathematics, Statistics, and Operations Research, Victoria University of Wellington, PO Box 600, Wellington, 6140, New Zealand)
1996-01-01
Schwinger's Dynamical Casimir Effect is one of several candidate explanations for sonoluminescence. Recently, several papers have claimed that Schwinger's estimate of the Casimir energy involved is grossly inaccurate. In this letter, we show that these calculations omit the crucial volume term. When the missing term is correctly included one finds full agreement with Schwinger's result for the Dynamical Casimir Effect. We have nothing new to say about sonoluminescence itself except to affirm ...
Finite Temperature Casimir Effect for Corrugated Plates
ZHAO Yan; SHAO Cheng-Gang; LUO Jun
2006-01-01
@@ Using the path-integral method, the corrections to the Casimir energy due to the combined effect of surface roughness and the finite temperature are calculated. For the specific case of two sinusoidally corrugated plates,the lateral Casimir force at finite temperature is obtained. The amplitude of the lateral Casimir force has a maximum at an optimal wavelength of λ≈ 2H with the mean plate distance H. This optimal parameter relation is almost independent of temperature.
The Casimir Effect for Thick Pistons
Fucci, Guglielmo
2015-01-01
In this work we analyze the Casimir energy and force for a {\\it thick} piston configuration. This study is performed by utilizing the spectral zeta function regularization method. The results we obtain for the Casimir energy and force depend explicitly on the parameters that describe the general self-adjoint boundary conditions imposed. Numerical results for the Casimir force are provided for specific types of boundary conditions and are also compared to the corresponding force on an infinite...
Surface impedance and the Casimir force
Bezerra, V.B.; Klimchitskaya, G. L.; Romero, C.
2001-01-01
The impedance boundary condition is used to calculate the Casimir force in configurations of two parallel plates and a shpere (spherical lens) above a plate at both zero and nonzero temperature. The impedance approach allows one to find the Casimir force between the realistic test bodies regardless of the electromagnetic fluctuations inside the media. Although this approach is an approximate one, it has wider areas of application than the Lifshitz theory of the Casimir force. The general form...
Thermal Casimir Force between Magnetic Materials
Klimchitskaya, G. L.; Geyer, B.; Mostepanenko, V. M.
2009-01-01
We investigate the Casimir pressure between two parallel plates made of magnetic materials at nonzero temperature. It is shown that for real magnetodielectric materials only the magnetic properties of ferromagnets can influence the Casimir pressure. This influence is accomplished through the contribution of the zero-frequency term of the Lifshitz formula. The possibility of the Casimir repulsion through the vacuum gap is analyzed depending on the model used for the description of the dielectr...
Halving the Casimir force with Conductive Oxides
WIJNGAARDEN, R. J.; Man, de, F.H.; Heeck, K.; Iannuzzi, D
2009-01-01
The possibility to modify the strength of the Casimir effect by tailoring the dielectric functions of the interacting surfaces is regarded as a unique opportunity in the development of Micro- and NanoElectroMechanical Systems. In air, however, one expects that, unless noble metals are used, the electrostatic force arising from trapped charges overcomes the Casimir attraction, leaving no room for exploitation of Casimir force engineering at ambient conditions. Here we show that, in the presenc...
QFT Limit of the Casimir Force
Scandurra, Marco
2003-01-01
High precision measurements of the Casimir effect and recent applications to micro electromechanical systems raise the question of how large the Casimir force can be made in an arbitrarily small device. Using a simple model for the metal boundary in which the metal is perfectly conducting at frequencies below plasma frequency omega_p and perfectly transparent above such frequency, I find that the Casimir force for plate separations a
Detecting Chameleons through Casimir Force Measurements
Brax, Philippe; van de Bruck, Carsten; Davis, Anne-Christine; Mota, David F.; Shaw, Douglas
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 ...
Reduction of the Casimir force using aerogels
Esquivel-Sirvent, R.
2007-01-01
By using silicon oxide based aerogels we show numerically that the Casimir force can be reduced several orders of magnitude, making its effect negligible in nanodevices. This decrease in the Casimir force is also present even when the aerogels are deposited on metallic substrates. To calculate the Casimir force we model the dielectric function of silicon oxide aerogels using an effective medium dielectric function such as the Clausius-Mossotti approximation. The results show that both the por...
The electromagnetic Casimir effect of spherical cavity
无
2003-01-01
The Casimir effect results from the zero-point energy of vacuum. A spherical cavity can be divided into three regions, and we make an analysis of every region and then give a formal solution of Casimir energy. The zeta-function regularization is also used to dispel the divergence of the summation. At the end, we can see the Casimir effect of a single sphere is included in our results.
Electrostatic patch potentials in Casimir force measurements
Garrett, Joseph; Somers, David; Munday, Jeremy
2015-03-01
Measurements of the Casimir force require the elimination of the electrostatic force between interacting surfaces. The force can be minimized by applying a potential to one of the two surfaces. However, electrostatic patch potentials remain and contribute an additional force which can obscure the Casimir force signal. We will discuss recent measurements of patch potentials made with Heterodyne Amplitude-Modulated Kelvin Probe Force Microscopy that suggest patches could be responsible for >1% of the signal in some Casimir force measurements, and thus make the distinction between different theoretical models of the Casimir force (e.g. a Drude-model or a plasma-model for the dielectric response) difficult to discern.
Of Some Theoretical Significance Implications of Casimir Effects
MacLay, G J; Milonni, P W; Fearn, Heidi; Milonni, Peter W.
2001-01-01
In his autobiography Casimir barely mentioned the Casimir effect, but remarked that it is "of some theortical significance." We will describe some aspects of Casimir effects that appear to be of particular significance now, more than half a century after Casimir's famous paper.
The Reality of Casimir Friction
Milton, K A; Brevik, I
2015-01-01
For more than 35 years theorists have studied quantum or Casimir friction, which occurs when two smooth bodies move transversely to each other, experiencing a frictional dissipative force due to quantum fluctuations. These forces are typically very small, unless the bodies are nearly touching, and consequently such effects have never been observed, although lateral Casimir forces have been seen for corrugated surfaces. Because of the lack of contact with phenomena, theoretical predictions for the frictional force between parallel plates, or between a polarizable atom and a metallic plate, have varied widely. Here we review the history of these calculations, show that theoretical consensus is emerging, and offer some hope that it might be possible to experimentally confirm this phenomenon of dissipative quantum electrodynamics.
Nonadditivity of critical Casimir forces
Paladugu, Sathyanarayana; Callegari, Agnese; Tuna, Yazgan; Barth, Lukas; Dietrich, Siegfried; Gambassi, Andrea; Volpe, Giovanni
2016-04-01
In soft condensed matter physics, effective interactions often emerge due to the spatial confinement of fluctuating fields. For instance, microscopic particles dissolved in a binary liquid mixture are subject to critical Casimir forces whenever their surfaces confine the thermal fluctuations of the order parameter of the solvent close to its critical demixing point. These forces are theoretically predicted to be nonadditive on the scale set by the bulk correlation length of the fluctuations. Here we provide direct experimental evidence of this fact by reporting the measurement of the associated many-body forces. We consider three colloidal particles in optical traps and observe that the critical Casimir force exerted on one of them by the other two differs from the sum of the forces they exert separately. This three-body effect depends sensitively on the distance from the critical point and on the chemical functionalisation of the colloid surfaces.
Supersymmetry Breaking Casimir Warp Drive
Obousy, Richard K.
2005-01-01
Within the framework of brane-world models it is possible to account for the cosmological constant by assuming supersymmetry is broken on the 3-brane but preserved in the bulk. An effective Casimir energy is induced on the brane due to the boundary conditions imposed on the compactified extra dimensions. It will be demonstrated that modification of these boundary conditions allows a spacecraft to travel at any desired speed due to a local adjustment of the cosmological constant which effectiv...
Casimir force: an alternative treatment
Silva, P. R.
2009-01-01
The Casimir force between two parallel uncharged closely spaced metallic plates is evaluated in ways alternatives to those usually considered in the literature. In a first approximation we take in account the suppressed quantum numbers of a cubic box, representing a cavity which was cut in a metallic block. We combine these ideas with those of the MIT bag model of hadrons, but adapted to non-relativistic particles. In a second approximation we consider the particles occupying the energy level...
Herdegen, Andrzej
2000-01-01
Two thin conducting, electrically neutral, parallel plates forming an isolated system in vacuum exert attracting force on each other, whose origin is the quantum electrodynamical interaction. This theoretical hypothesis, known as Casimir effect, has been also confirmed experimentally. Despite long history of the subject, no completely convincing theoretical analysis of this effect appears in the literature. Here we discuss the effect (for the scalar field) anew, on a revised physical and math...
Numerical calculation of Casimir forces
Kilen, Isak Ragnvald
2012-01-01
In this thesis a set of regularized boundary integral equation are introduced that can be used to calculate the Casimir force induced by a two dimensional scalar field. The boundary integral method is compared to the functional integral method and mode summation where possible. Comparisons are done for the case of two parallel plates, two concentric circles and two adjacent circles. The results indicate that the boundary integral method correctly predicts the geometry dependence of the C...
Kralli, A.; Moss, S.H.
1987-06-01
Near-UV radiation (365 nm)-induced lethality, as measured by colony-forming ability, showed an actinic reticuloid cell strain to be sensitive relative to normal human fibroblasts, when irradiated at 25/sup 0/C. This effect was not seen after far-UV (254 nm) irradiation. Trolox-C, a water-soluble analogue of vitamin E, incorporated in the pre-irradiation growth medium or in the post-irradiation plating medium, protected the actinic reticuloid cells to the extent that they were as resistant as normal cells. Plating medium containing Trolox-C did not provide differential protection against inactivation of the two cell strains by wavelengths in the far-UV region. The protection provided by Trolox-C, an analogue of the natural antioxidant vitamin E, suggests some free radical involvement in the aetiology of the disease.
Mode contributions to the Casimir effect
Intravaia, Francesco
2009-01-01
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.
Nonequilibrium thermal Casimir-Polder forces
We study the nonequilibrium Casimir-Polder force on an atom prepared in an incoherent superposition of internal energy eigenstates, which is placed in a magnetoelectric environment of nonuniform temperature. After solving the coupled atom-field dynamics within the framework of macroscopic quantum electrodynamics, we derive a general expression for the thermal Casimir-Polder force.
Resource Letter CF-1: Casimir Force
Lamoreaux, S.K. [University of California, Los Alamos National Laboratory, Physics Division P-23, M.S. H803, Los Alamos, New Mexico 87545 (United States)
1999-10-01
This resource letter provides an introductory guide to the literature on the Casimir force. Journal articles and books are cited for the following topics: introductory articles and books, calculations, dynamical Casimir effect, mechanical analogs, applications, and experiments. {copyright} {ital 1999 American Association of Physics Teachers.}
The Casimir force for passive mirrors
Lambrecht, A.; Jaekel, M. -T.; Reynaud, S.
1998-01-01
We show that the Casimir force between mirrors with arbitrary frequency dependent reflectivities obeys bounds due to causality and passivity properties. The force is always smaller than the Casimir force between two perfectly reflecting mirrors. For narrow-band mirrors in particular, the force is found to decrease with the mirrors bandwidth.
La force de Casimir et les plasmons de surface
Intravaia, F.; Lambrecht, A.; Reynaud, S.
2004-11-01
La présence de fluctuations irréductibles de champ dans le vide est une prédiction importante de la théorie quantique. Ces fluctuations ont de nombreux effets bien connus, dont l'archétype est la force de Casimir apparaîssant entre deux miroirs placés dans le vide par suite de la pression de radiation du vide. Elle a été récemment mesurée avec une précision de l'ordre du %. De nombreux travaux sont consacrés à l'évaluation théorique de cette force en visant une précision du même ordre. Ici nous étudions la force de Casimir dans la configuration de deux miroirs métalliques plans parallèles à température nulle. En supposant les miroirs décrits par un modèle plasma nous interprétons la force de Casimir comme le résultat de l'interaction entre les plasmons de surface des deux miroirs.
Halving the Casimir force with conductive oxides.
de Man, S; Heeck, K; Wijngaarden, R J; Iannuzzi, D
2009-07-24
The possibility to modify the strength of the Casimir effect by tailoring the dielectric functions of the interacting surfaces is regarded as a unique opportunity in the development of micro- and nanoelectromechanical systems. In air, however, one expects that, unless noble metals are used, the electrostatic force arising from trapped charges overcomes the Casimir attraction, leaving no room for exploitation of Casimir force engineering at ambient conditions. Here we show that, in the presence of a conductive oxide, the Casimir force can be the dominant interaction even in air, and that the use of conductive oxides allows one to reduce the Casimir force up to a factor of 2 when compared to noble metals. PMID:19659332
Controlling Casimir force via coherent driving field
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.
Casimir-Lifshitz force out of thermal equilibrium between arbitrary bodies
Messina, Riccardo
2010-01-01
We derive the Casimir-Lifshitz force acting between two arbitrary bodies, each one held at a given temperature, surrounded by environmental radiation at a third temperature. The system, in stationary configuration out of thermal equilibrium, is characterized by a force depending on the three temperatures, and explicitly expressed in terms of the scattering operators of each body. Our predictions, valid for bodies of any geometry and dielectric properties, can be relevant for experimental and technological purposes in the domain of Casimir interactions and of heat transfer.
Distinguishing de Sitter universe from thermal Minkowski spacetime by Casimir-Polder-like force
Tian, Zehua; Jing, Jiliang
2014-07-01
We demonstrate that the static ground state atom, which interacts with a conformally coupled massless scalar field in the de Sitter invariant vacuum, can obtain a position-dependent energy-level shift and this shift could cause a Casimir-Polder-like force on it. Interestingly no such force arises on the inertial atom bathed in a thermal radiation in the Minkowski universe. Thus, although the energy-level shifts of the static atom for these two cases are structurally the same, whether the energy-level shift causes the Casimir-Polder-like force, in principle, could be as an indicator to distinguish de Sitter universe from the thermal Minkowski spacetime.
The Casimir force between an ideal metal plate and a dissipative dielectric slab
Falinejad, H.; Bayat, F.
2014-09-01
In this research, a general formula for the Casimir force between ideal metal plate and a dissipative dielectric slab has been obtained. The dielectric function of the slab is assumed to be an arbitrary complex function of frequency satisfying Kramers-Kronig relations. A classical expression for the radiation pressure of the vacuum fields on the slab is presented by using the Maxwell stress tensor. With the transition to the quantum domain and using the fluctuation dissipation theorem and Kubo's formula, the resulting expression is written in terms of the imaginary part of the vector potential Green functions components of the system. Finally, by computing the Green function, the Casimir force on the slab is obtained. This formalism enables us to calculate the Casimir force without resorting to the explicit form of the field operators. The general expression is confirmed by limiting and comparing with one of the previous works.
Anomalous temperature dependence of the Casimir force for thin metal films.
Yampol'skii, V A; Savel'ev, Sergey; Mayselis, Z A; Apostolov, S S; Nori, Franco
2008-08-29
Within the framework of the Drude dispersive model, we predict an unusual nonmonotonic temperature dependence of the Casimir force for thin metal films. For certain conditions, this force decreases with temperature due to the decrease of the metallic conductivity, whereas the force increases at high temperatures due to the increase of the thermal radiation pressure. We consider the attraction of a film to: either (i) a bulk ideal metal with a planar boundary, or (ii) a bulk metal sphere (lens). The experimental observation of the predicted decreasing temperature dependence of the Casimir force can put an end to the long-standing discussion on the role of the electron relaxation in the Casimir effect. PMID:18851637
Precise determination of the Casimir force and first realization of a "Casimir less" experiment
Decca, R. S.; Lopez, D.; Chan, H. B.; Fischbach, E.; Klimchitskaya, G. L.; Krause, D. E.; Mostepanenkot, V. M.
2004-01-01
We present improved Casimir effect measurements. The attractive force between a metallized sphere and the coated plate of a Si microelectro mechanical oscillator is measured with unparalleled precision. The same setup, but in a dynamic scheme, yields a determination of the Casimir pressure between two infinite plates. Since the Casimir force is the dominant interaction in the 0.11 mum range under these experimental conditions, it acts as a background in the search for new forces in the submic...
The Casimir effect: a force from nothing
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.)
The Casimir effect: a force from nothing
Lambrecht, Astrid [Laboratoire Kastler Brossel, Universite Pierre et Marie Curie, Ecole Normale Superieure, Centre National de Recherche Scientifique, Campus Jussieu, Case 74, Paris (France)]. E-mail: lambrecht@spectro.jussieu.fr
2002-09-01
The attractive force between two surfaces in a vacuum - first predicted by Hendrik Casimir over 50 years ago - could affect everything from micromachines 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 micromachined 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.)
Self-similar plates: Casimir energies
Shajesh, K V; Cavero-Peláez, Inés; Parashar, Prachi
2016-01-01
We construct various self-similar configurations using parallel $\\delta$-function plates and show that it is possible to evaluate the Casimir interaction energy of these configurations using the idea of self-similarity alone. We restrict our analysis to interactions mediated by a scalar field, but the extension to electromagnetic field is immediate. Our work unveils an easy and powerful method that can be easily employed to calculate the Casimir energies of a class of self-similar configurations. As a highlight, in an example, we determine the Casimir interaction energy of a stack of parallel plates constructed by positioning $\\delta$-function plates at the points constituting the Cantor set, a prototype of a fractal. This, to our knowledge, is the first time that the Casimir energy of a fractal configuration has been reported. Remarkably, the Casimir energy of some of the configurations we consider turn out to be positive, and a few even have zero Casimir energy. For the case of positive Casimir energy that ...
Casimir force on a solid ball when ε(ω)μ(ω) = 1
The Casimir surface force on a solid ball is calculated, assuming the material to be dispersive and to be satisfying the condition ε(ω)μ(ω) = 1, ε(ω) being the spectral permittivity and μ(ω) the spectral permeability. This particular condition simplifies the Casimir theory of dielectric media considerably. As a dispersion relation we choose the analogue of Sellmeir's form (with one absorption frequency), known from ordinary dispersion theory. We follow a combined numerical and analytic approach: the low values of the angular momentum variable are treated numerically, whereas the higher values are treated analytically by means of the Debye expansion. The dispersive effect is found to yield a strong, attractive contribution to the surface force. If the cutoff frequency ω0 is large, the dispersion-induced surface force becomes proportional to ω0.tions
The holographic supersymmetric Casimir energy
Genolini, Pietro Benetti; Martelli, Dario; Sparks, James
2016-01-01
We consider a general class of asymptotically locally AdS_5 solutions of minimal gauged supergravity, that are dual to superconformal field theories on curved backgrounds S^1 x M_3 preserving two supercharges. We demonstrate that standard holographic renormalization corresponds to a scheme that breaks supersymmetry. We propose new boundary terms that restore supersymmetry, and show that for smooth solutions with topology S^1 x R^4 the improved on-shell action reproduces both the supersymmetric Casimir energy and the field theory BPS relation between charges.
Supersymmetry Breaking Casimir Warp Drive
Obousy, R K
2005-01-01
Within the framework of brane-world models it is possible to account for the cosmological constant by assuming supersymmetry is broken on the 3-brane but preserved in the bulk. An effective Casimir energy is induced on the brane due to the boundary conditions imposed on the compactified extra dimensions. It will be demonstrated that modification of these boundary conditions allows a spacecraft to travel at any desired speed due to a local adjustment of the cosmological constant which effectively contracts/expands space-time in the front/rear of the ship resulting in motion potentially faster than the speed of light as seen by observers outside the disturbance.
Supersymmetry Breaking Casimir Warp Drive
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
Casimir-force-driven ratchets.
Emig, T
2007-04-20
We explore the nonlinear dynamics of two parallel periodically patterned metal surfaces that are coupled by the zero-point fluctuations of the electromagnetic field between them. The resulting Casimir force generates for asymmetric patterns with a time periodically driven surface-to-surface distance a ratchet effect, allowing for directed lateral motion of the surfaces in sizable parameter ranges. It is crucial to take into account inertia effects and hence chaotic dynamics which are described by Langevin dynamics. Multiple velocity reversals occur as a function of driving, mean surface distance, and effective damping. These transport properties are shown to be stable against weak ambient noise. PMID:17501407
Casimir effect from macroscopic quantum electrodynamics
Philbin, T G
2011-01-01
The canonical quantization of macroscopic electromagnetism was recently presented in New J. Phys. 12 (2010) 123008. This theory is here used to derive the Casimir effect, by considering the special case of thermal and zero-point fields. The stress-energy-momentum tensor follows from Noether's theorem, and its electromagnetic part in thermal equilibrium gives the Casimir energy density and stress tensor. The results hold for arbitrary inhomogeneous magnetodielectrics and are obtained from a rigorous quantization of electromagnetism in dispersive, dissipative media. Continuing doubts about the status of the standard Lifshitz theory as a proper quantum treatment of Casimir forces do not apply to the derivation given here.
Coupled surface polaritons and the Casimir force
Henkel, C; Mulet, J P; Greffet, J J; Henkel, Carsten; Joulain, Karl; Mulet, Jean-Philippe; Greffet, Jean-Jacques
2004-01-01
The Casimir force between metallic plates made of realistic materials is evaluated for distances in the nanometer range. A spectrum over real frequencies is introduced and shows narrow peaks due to surface resonances (plasmon polaritons or phonon polaritons) that are coupled across the vacuum gap. We demonstrate that the Casimir force originates from the attraction (repulsion) due to the corresponding symmetric (antisymmetric) eigenmodes, respectively. This picture is used to derive a simple analytical estimate of the Casimir force at short distances. We recover the result known for Drude metals without absorption and compute the correction for weakly absorbing materials.
The OH-induced deamination and dephosphorylation of simple peptides and phosphate esters in oxygenated solutions involve the fomation and subsequent degradation of the perodyl radicals RCONHC(/dot O/)R2 and /bigcirc P/ OC(/dot O/2)R2 respectively. Reaction analogues in the degradation of peroxyl and alkoxyl radicals in these two systems are evaluated with reference to the OH-induced main-chain cleavage of protein and DNA. 25 refs
Casimir force: an alternative treatment
Silva, P R
2009-01-01
The Casimir force between two parallel uncharged closely spaced metallic plates is evaluated in ways alternatives to those usually considered in the literature. In a first approximation we take in account the suppressed quantum numbers of a cubic box, representing a cavity which was cut in a metallic block. We combine these ideas with those of the MIT bag model of hadrons, but adapted to non-relativistic particles. In a second approximation we consider the particles occupying the energy levels of the Bohr atom, so that the Casimir force depends explicitly on the fine structure constant alpha. In both treatments, the mean energies which have explicit dependence on the particle mass and on the maximum occupied quantum number (related to the Fermi level of the system) at the beginning of the calculations, have these dependences mutually canceled at the end of them. Finally by comparing the averaged energies computed in both approximations, we are able to make an estimate of the value of the fine structure consta...
Onsager-Casimir relations revisited
The authors study the fate of the Onsager-Casimir reciprocity relations for a continuous system when some of its variables are eliminated adiabatically. Just as for discrete systems, deviations appear in correction terms to the reduced evolution equation that are of higher order in the time scale ratio. The deviations are not removed by including correction terms to the coarse-grained thermodynamic potential. However, via a reformulation of the theory, in which the central role of the thermodynamic potential is taken over by an associated Lagrangian-type expression, they arrive at a modified form of the Onsager-Casimir relations that survives the adiabatic elimination procedure. There is a simple relation between the time evolution of the redefined thermodynamic forces and that of the basic thermodynamic variables; this relation also survives the adiabatic elimination. The formalism is illustrated by explicit calculations for the Klein-Kramers equation, which describes the phase space distribution of Brownian particles, and for the corrected Smoluchowski equation derived from it by adiabatic elimination of the velocity variable. The symmetry relation for the latter leads to a simple proof that the reality of the eigenvalues of the simple Smoluchowski equation is not destroyed by the addition of higher order corrections, at least not within the framework of a formal perturbation expansion in the time scale ratio
The Casimir energy in a separable potential
The Casimir energy is the first-order-in-h correction to the energy of a time-independent field configuration in a quantum field theory. We study the Casimir energy in a toy model, where the classical field is replaced by a separable potential. In this model the exact answer is trivial to compute, making it a good place to examine subtleties of the problem. We construct two traditional representations of the Casimir energy, one from the Green's function and the other from the phase shifts, and apply them to this case. We show that the two representations are correct and equivalent in this model. We study the convergence of the Born approximation to the Casimir energy and relate our findings to computational issues that arise in more realistic models. (c) 2000 Academic Press, Inc
Casimir force between integrable and chaotic pistons
We have computed numerically the Casimir force between two identical pistons inside a very long cylinder, considering different shapes for the pistons. The pistons can be considered quantum billiards, whose spectrum determines the vacuum force. The smooth part of the spectrum fixes the force at short distances and depends only on geometric quantities like the area or perimeter of the piston. However, correcting terms to the force, coming from the oscillating part of the spectrum which is related to the classical dynamics of the billiard, could be qualitatively different for classically integrable or chaotic systems. We have performed a detailed numerical analysis of the corresponding Casimir force for pistons with regular and chaotic classical dynamics. For a family of stadium billiards, we have found that the correcting part of the Casimir force presents a sudden change in the transition from regular to chaotic geometries. This suggests that there could be signatures of quantum chaos in the Casimir effect.
Casimir force between Chern-Simons surfaces
Bordag, M.; Vassilevich, D.V.(CMCC-Universidade Federal do ABC, Santo André, SP, Brazil)
1999-01-01
We calculate the Casimir force between two parallel plates if the boundary conditions for the photons are modified due to presence of the Chern-Simons term. We show that this effect should be measurable within the present experimental technique.
Casimir forces of metallic microstructures into cavities
Kenanakis, George; Soukoulis, Costas M.; Economou, Eleftherios N.
2015-08-01
A theoretical estimate of the Casimir force of a metallic structure embedded into a cubic cavity is proposed. We demonstrate that by calculating the eigenmodes of the system we can determine the Casimir force, which can be either attractive or repulsive, by simply changing the geometry of the structures relative to the walls of the cavity. In this analysis, several cases of structures are taken into account, from rectangular slabs to chiral "omega" particles, and the predicted data are consistent with recent literature. We demonstrate that the sidewalls of the studied cavity contribute decisively to the repulsive Casimir force between the system and the nearby top surface of the cavity. Finally, we provide evidence that the medium embedded into the studied cavity (and especially its permittivity) can change the intensity of the Casimir force, while its repulsive nature, once established (owing to favorable geometrical features), remains quite robust.
Is the Casimir effect relevant to sonoluminescence?
The Casimir energy of a solid ball (or cavity in an infinite medium) is calculated by a direct frequency summation using the contour integration. The dispersion is taken into account, and the divergences are removed by making use of the zeta function technique. The Casimir energy of a dielectric ball (or cavity) turns out to be positive, it being increased when the radius of the ball decreases. The latter eliminates completely the possibility of explaining, via the Casimir effect, the sonoluminescence for bubbles in a liquid. Besides, the Casimir energy of the air bubbles in water proves to be immensely smaller than the amount of the energy emitted in a sonoluminescent flash. The dispersive effect is shown to be inessential for the final result
Scattering Theory Approach to Electrodynamic Casimir Forces
Rahi, Sahand Jamal; Graham, Noah; Jaffe, Robert L; Kardar, Mehran
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 re-deriving the Lifshitz formula for infinite half spaces, by demonstrating the Casimir-Polder to van der Waals cross-over, 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 oppos...
Obol, Mahmut
2013-01-01
Ferrites are distinct material for electromagnetic applications due to its unique spin precession. In this paper, Casimir pressure effect by deploying magnetically tunable surface plasmon quanta in stratified structure of using ferrite and metal wires is presented. Previously, oscillating surface plasmon quanta were successfully included to modify first reflection and first transmission characteristics. The oscillating surface plasmon quanta in the modified reflection in such a system, not only does resolve in a typical matter in metamaterial, but also provide new applications such as creating Casimir pressure effects through the metamaterial composite shown in this paper. The Casimir pressure flips from attractive state to repulsive state is referred to actual cause mechanism of radiation from surface plasmon quanta. Both Casimir force analysis and the measured data of radiations indicate us the system develops quantized states by electric flux induced by ferromagnetic resonance, so we also carried quantum a...
Surface Screening in the Casimir Force
Contreras-Reyes, Ana M.; Mochán, W. Luis
2005-01-01
We calculate the corrections to the Casimir force between two metals due to the spatial dispersion of their response functions. We employ model-independent expressions for the force in terms of the optical coefficients. We express the non-local corrections to the Fresnel coefficients employing the surface $d_\\perp$ parameter, which accounts for the distribution of the surface screening charge. Within a self-consistent jellium calculation, spatial dispersion increases the Casimir force signifi...
Casimir Friction Force Between Polarizable Media
Høye, Johan S.; Brevik, Iver
2012-01-01
This work is a continuation of our recent series of papers on Casimir friction, for a pair of particles of low relative particle velocity. Each particle is modeled as a simple harmonic oscillator. Our basic method, as before, is the use of quantum mechanical statistical mechanics, involving the Kubo formula, at finite temperature. In this work we begin by analyzing the Casimir friction between two particles polarizable in all spatial directions, this being a generalization of our study in EPL...
Casimir force induced by imperfect Bose gas
Napiorkowski, Marek; Piasecki, Jaroslaw
2011-01-01
We present a study of the Casimir effect in an imperfect (mean-field) Bose gas contained between two infinite parallel plane walls. The derivation of the Casimir force follows from the calculation of the excess grand canonical free energy density under periodic, Dirichlet, and Neumann boundary conditions with the use of the steepest descent method. In the one-phase region the force decays exponentially fast when distance $D$ between the walls tends to infinity. When Bose-Einstein condensation...
Temperature Dependence of the Casimir Force
Brevik, Iver; Høye, Johan S.
2013-01-01
The Casimir force - at first a rather unexpected consequence of quantum electrodynamics - was discovered by Hendrik Casimir in Eindhoven in 1948. It predicts that two uncharged metal plates experience an attractive force because of the zero-point fluctuations of the electromagnetic field. The idea was tested experimentally in the 1950's and 1960's, but the results were not so accurate that one could make a definite conclusion regarding the existence of the effect. Evgeny Lifshitz expanded the...
Sample dependence of the Casimir force
Pirozhenko, I.; Lambrecht, A.; Svetovoy, V.B.
2006-01-01
We have analysed available optical data for Au in the mid-infrared range which is important for a precise prediction of the Casimir force. Significant variation of the data demonstrates genuine sample dependence of the dielectric function. We demonstrate that the Casimir force is largely determined by the material properties in the low frequency domain and argue that therefore the precise values of the Drude parameters are crucial for an accurate evaluation of the force. These parameters can ...
The Casimir force between rough metallic plates
Genet, Cyriaque; Lambrecht, Astrid; Neto, Paulo Maia; Reynaud, Serge
2003-01-01
The Casimir force between two metallic plates is affected by their roughness state. This effect is usually calculated through the so-called `proximity force approximation' which is only valid for small enough wavevectors in the spectrum of the roughness profile. We introduce here a more general description with a wavevector-dependent roughness sensitivity of the Casimir effect. Since the proximity force approximation underestimates the effect, a measurement of the roughness spectrum is needed...
The Casimir force between metallic mirrors
Lambrecht, Astrid; Genet, Cyriaque; Reynaud, Serge
2001-01-01
In order to compare recent experimental results with theoretical predictions we study the influence of finite conductivity of metals on the Casimir effect. The correction to the Casimir force and energy due to imperfect reflection and finite temperature are evaluated for plane metallic plates where the dielectric functions of the metals are modeled by a plasma model. The results are compared with the common approximation where conductivity and thermal corrections are evaluated separately and ...
Quantitative non contact dynamic Casimir force measurements
Jourdan, Guillaume; Lambrecht, Astrid; Comin, Fabio; Chevrier, Joël
2009-01-01
We show that the Casimir force gradient can be quantitatively measured with no contact involved. Results of the Casimir force measurement with systematic uncertainty of 3% are presented for the distance range of 100-600 nm. The statistical uncertainty is shown to be due to the thermal fluctuations of the force probe. The corresponding signal to noise ratio equals unity at the distance of 600 nm. Direct contact between surfaces used in most previous studies to determine absolute distance separ...
Coupled surface polaritons and the Casimir force
Henkel, Carsten; Joulain, Karl; Mulet, Jean-Philippe; Greffet, Jean-Jacques
2003-01-01
The Casimir force between metallic plates made of realistic materials is evaluated for distances in the nanometer range. A spectrum over real frequencies is introduced and shows narrow peaks due to surface resonances (plasmon polaritons or phonon polaritons) that are coupled across the vacuum gap. We demonstrate that the Casimir force originates from the attraction (repulsion) due to the corresponding symmetric (antisymmetric) eigenmodes, respectively. This picture is used to derive a simple ...
The Casimir force: background, experiments, and applications
Lamoreaux, Steven K [Los Alamos National Laboratory, University of California, Physics Division P-23, M.S. H803, Los Alamos, NM 87545 (United States)
2005-01-01
The Casimir force, which is the attraction of two uncharged material bodies due to modification of the zero-point energy associated with the electromagnetic modes in the space between them, has been measured with per cent-level accuracy in a number of recent experiments. A review of the theory of the Casimir force and its corrections for real materials and finite temperature are presented in this report. Applications of the theory to a number of practical problems are discussed.
Thermal Casimir force between nanostructured surfaces
Guérout, R.; Lussange, J.; Chan, H. B.; Lambrecht, A.; Reynaud, S.
2012-01-01
We present detailed calculations for the Casimir force between a plane and a nanostructured surface at finite temperature in the framework of the scattering theory. We then study numerically the effect of finite temperature as a function of the grating parameters and the separation distance. We also infer non-trivial geometrical effects on the Casimir interaction via a comparison with the proximity force approximation. Finally, we compare our calculations with data from experiments performed ...
Thermal Casimir interaction between two magnetodielectric plates
We investigate the thermal Casimir interaction between two magnetodielectric plates made of real materials. On the basis of the Lifshitz theory, it is shown that for diamagnets and for paramagnets in the broad sense (with exception of ferromagnets) the magnetic properties do not influence the magnitude of the Casimir force. For ferromagnets, taking into account the realistic dependence of magnetic permeability on frequency, we conclude that the impact of magnetic properties on the Casimir interaction arises entirely from the contribution of the zero-frequency term in the Lifshitz formula. The computations of the Casimir free energy and pressure are performed for the configurations of two plates made of ferromagnetic metals (Co and Fe), for one plate made of ferromagnetic metal and the other of nonmagnetic metal (Au), for two ferromagnetic dielectric plates (on the basis of polystyrene), and for a ferromagnetic dielectric plate near a nonmagnetic metal plate. The dielectric permittivity of metals is described using both the Drude and the plasma model approaches. It is shown that the Casimir repulsion through the vacuum gap can be realized in the configuration of a ferromagnetic dielectric plate near a nonmagnetic metal plate described by the plasma model. In all cases considered, the respective analytical results in the asymptotic limit of large separations between the plates are obtained. The impact of the magnetic phase transition through the Curie temperature on the Casimir interaction is considered. In conclusion, we propose several experiments allowing to determine whether the magnetic properties really influence the Casimir interaction and to independently verify the Drude and plasma model approaches to the thermal Casimir force.
Acoustic Casimir Pressure for Arbitrary Media
Barcenas, J.; Reyes, L.; Esquivel-Sirvent, R.
2004-01-01
In this paper we derive a general expression for the acoustic Casimir pressure between two parallel slabs made of arbitrary materials and whose acoustic reflection coefficients are not equal. The formalism is based on the calculation of the local density of modes using a Green's function approach. The results for the Casimir acoustic pressure are generalized to a sphere/plate configuration using the proximity theorem
Curved Casimir Operators and the BGG Machinery
Andreas Cap; Vladimír Soucek
2007-01-01
We prove that the Casimir operator acting on sections of a homogeneous vector bundle over a generalized flag manifold naturally extends to an invariant differential operator on arbitrary parabolic geometries. We study some properties of the resulting invariant operators and compute their action on various special types of natural bundles. As a first application, we give a very general construction of splitting operators for parabolic geometries. Then we discuss the curved Casimir operators on...
Casimir-Polder forces: A nonperturbative approach
Within the frame of macroscopic QED in linear, causal media, we study the radiation force of Casimir-Polder type acting on an atom which is positioned near dispersing and absorbing magnetodielectric bodies and initially prepared in an arbitrary electronic state. It is shown that minimal and multipolar coupling lead to essentially the same lowest-order perturbative result for the force acting on an atom in an energy eigenstate. To go beyond perturbation theory, the calculations are based on the exact center-of-mass equation of motion. For a nondriven atom in the weak-coupling regime, the force as a function of time is a superposition of force components that are related to the electronic density matrix elements at a chosen time. Even the force component associated with the ground state is not derivable from a potential in the ususal way, because of the position dependence of the atomic polarizability. Further, when the atom is initially prepared in a coherent superposition of energy eigenstates, then temporally oscillating force components are observed, which are due to the interaction of the atom with both electric and magnetic fields
Messina, Riccardo
2011-01-01
We study the radiative heat transfer and the Casimir-Lifshitz force occurring between two bodies in a system out of thermal equilibrium. We consider bodies of arbitrary shape and dielectric properties, held at two different temperatures, and immersed in a environmental radiation at a third different temperature. We derive explicit closed-form analytic expressions for the correlations of the electromagnetic field, and for the heat transfer and Casimir-Lifshitz force, in terms of the bodies scattering matrices. We then consider some particular cases which we investigate in detail: the atom-surface and the slab-slab configurations.
Messina, Riccardo [LNE-SYRTE, Observatoire de Paris, CNRS UMR 8630, UPMC, 61 avenue de l' Observatoire, F-75014 Paris (France); Antezza, Mauro [Universite Montpellier 2, Laboratoire Charles Coulomb UMR 5221, F-34095, Montpellier (France); CNRS, Laboratoire Charles Coulomb UMR 5221, F-34095, Montpellier (France)
2011-10-15
We study the radiative heat transfer and the Casimir-Lifshitz force occurring between two bodies in a system out of thermal equilibrium. We consider bodies of arbitrary shape and dielectric properties, held at two different temperatures and immersed in environmental radiation at a third different temperature. We derive explicit closed-form analytic expressions for the correlations of the electromagnetic field and for the heat transfer and Casimir-Lifshitz force in terms of the bodies' scattering matrices. We then consider some particular cases which we investigate in detail: the atom-surface and the slab-slab configurations.
We study the radiative heat transfer and the Casimir-Lifshitz force occurring between two bodies in a system out of thermal equilibrium. We consider bodies of arbitrary shape and dielectric properties, held at two different temperatures and immersed in environmental radiation at a third different temperature. We derive explicit closed-form analytic expressions for the correlations of the electromagnetic field and for the heat transfer and Casimir-Lifshitz force in terms of the bodies' scattering matrices. We then consider some particular cases which we investigate in detail: the atom-surface and the slab-slab configurations.
Casimir forces in a plasma: possible connections to Yukawa potentials
Ninham, Barry W.; Boström, Mathias; Persson, Clas; Brevik, Iver; Buhmann, Stefan Y.; Sernelius, Bo E.
2014-10-01
We present theoretical and numerical results for the screened Casimir effect between perfect metal surfaces in a plasma. We show how the Casimir effect in an electron-positron plasma can provide an important contribution to nuclear interactions. Our results suggest that there is a connection between Casimir forces and nucleon forces mediated by mesons. Correct nuclear energies and meson masses appear to emerge naturally from the screened Casimir-Lifshitz effect.
Casimir force in noncommutative Randall-Sundrum models revisited
Teo, L. P.
2010-01-01
We propose another method to compute the Casimir force in noncommutative Randall-Sundrum braneworld model considered by K. Nouicer and Y. Sabri recently. Our method can be used to compute the Casimir force to any order in the noncommutative parameter. Contrary to the claim made by K. Nouicer and Y. Sabri that repulsive Casimir force can appear in the first order approximation, we show that the Casimir force is always attractive at any order of approximation.
Casimir forces in a plasma: possible connections to Yukawa potentials
We present theoretical and numerical results for the screened Casimir effect between perfect metal surfaces in a plasma. We show how the Casimir effect in an electron-positron plasma can provide an important contribution to nuclear interactions. Our results suggest that there is a connection between Casimir forces and nucleon forces mediated by mesons. Correct nuclear energies and meson masses appear to emerge naturally from the screened Casimir-Lifshitz effect. (authors)
Solvent extraction of scandium from perchloric or hydrochloric acid aqueous systems into benzene solutions of tetraphenyl imidodiphosphate, (PhO)2P(O)NHP(O)(PhO)2 (henceforth HA) and its sulfur analogues containing P(O)NHP(S) or P(S)NHP(S) groups was studied. Behaving as weak acids in the aqueous phase, the reagents form complex extractable compounds ScA3 with scandium. The extraction constants were measured and found to be lower for the sulfur analogues than for the oxygen reagent. The configuration changes induced in the reagent by gamma irradiation with a 60Co source were studied by examining the extraction of scandium with the reagent and by 31P NMR measurements. Whereas the changes in the solid reagent are not very marked and appear only at doses in excess of 800 kGy, the reagent dissolved in benzene exhibits configuration changes even in the application of doses at the 10 kGy level. This fact is related to the presence of benzene and dissolved oxygen in the system. (author). 5 figs., 1 tab., 9 refs
Casimir forces for inhomogeneous planar media
Casimir forces arise from vacuum fluctuations. They are fully understood only for simple models, and are important in nano- and microtechnologies. We report our experience of computer algebra calculations towards the Casimir force for models involving inhomogeneous dielectrics. We describe a methodology that greatly increases confidence in any results obtained, and use this methodology to demonstrate that the analytic derivation of scalar Green's functions is at the boundary of current computer algebra technology. We further demonstrate that Lifshitz theory of electromagnetic vacuum energy can not be directly applied to calculate the Casimir stress for models of this type, and produce results that have led to alternative regularisations. Using a combination of our new computational framework and the new theory based on our results, we provide specific calculations of Casimir forces for planar dielectrics having permittivity that declines exponentially. We discuss the relative strengths and weaknesses of computer algebra systems when applied to this type of problem, and describe a combined numerical and symbolic computational framework for calculating Casimir forces for arbitrary planar models.
Surface impedance and the Casimir force
The impedance boundary condition is used to calculate the Casimir force in configurations of two parallel plates and a sphere (spherical lens) above a plate at both zero and nonzero temperature. The impedance approach allows one to find the Casimir force between the realistic test bodies regardless of the electromagnetic fluctuations inside the media. Although this approach is an approximate one, it has wider areas of application than the Lifshitz theory of the Casimir force. The general formulas of the impedance approach to the theory of the Casimir force are given and the formal substitution is found for connecting it with the Lifshitz formula. The range of micrometer separations between the test bodies, which is interesting from the experimental point of view, is investigated in detail. It is shown that at zero temperature the results obtained on the basis of the surface impedance method are in agreement with those obtained in framework of the Lifshitz theory within a fraction of a percent. The temperature correction to the Casimir force from the impedance method coincides with that from the Lifshitz theory up to four significant figures. The case of millimeter separations that corresponds to the normal skin effect is also considered. At zero temperature the obtained results have good agreement with the Lifshitz theory. At nonzero temperature the impedance approach is not subject to the interpretation problems peculiar to the zero-frequency term of the Lifshitz formula in dissipative media
Detecting chameleons through Casimir force measurements
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
Monte Carlo Simulation of Critical Casimir Forces
Vasilyev, Oleg A.
2015-03-01
In the vicinity of the second order phase transition point long-range critical fluctuations of the order parameter appear. The second order phase transition in a critical binary mixture in the vicinity of the demixing point belongs to the universality class of the Ising model. The superfluid transition in liquid He belongs to the universality class of the XY model. The confinement of long-range fluctuations causes critical Casimir forces acting on confining surfaces or particles immersed in the critical substance. Last decade critical Casimir forces in binary mixtures and liquid helium were studied experimentally. The critical Casimir force in a film of a given thickness scales as a universal scaling function of the ratio of the film thickness to the bulk correlation length divided over the cube of the film thickness. Using Monte Carlo simulations we can compute critical Casimir forces and their scaling functions for lattice Ising and XY models which correspond to experimental results for the binary mixture and liquid helium, respectively. This chapter provides the description of numerical methods for computation of critical Casimir interactions for lattice models for plane-plane, plane-particle, and particle-particle geometries.
Normal and lateral Casimir force: Advances and prospects
Klimchitskaya, G L
2010-01-01
We discuss recent experimental and theoretical results on the Casimir force between real material bodies made of different materials. Special attention is paid to calculations of the normal Casimir force acting perpendicular to the surface with the help of the Lifshitz theory taking into account the role of free charge carriers. Theoretical results for the thermal Casimir force acting between metallic, dielectric and semiconductor materials are presented and compared with available experimental data. Main attention is concentrated on the possibility to control the magnitude and sign of the Casimir force for applications in nanotechnology. In this respect we consider experiments on the optical modulation of the Casimir force between metal and semiconductor test bodies with laser light. Another option is the use of ferromagnetic materials, specifically, ferromagnetic dielectrics. Under some conditions this allows to get Casimir repulsion. The lateral Casimir force acting between sinusoidally corrugated surfaces...
Oscillating Casimir force between two slabs in a Fermi sea
Li-Wei, Chen; Guo-Zhen, Su; Jin-Can, Chen; Andresen, Bjarne Bøgeskov
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......The Casimir effect for two parallel slabs immersed in an ideal Fermi sea is investigated at both zero and nonzero temperatures. It is found that the Casimir effect in a Fermi gas is distinctly different from that in an electromagnetic field or a massive Bose gas. In contrast to the familiar result...
Probing the Casimir force with optical tweezers
Ether, D S; Umrath, S; Martinez, D; Ayala, Y; Pontes, B; Araújo, G R de S; Frases, S; Ingold, G -L; Rosa, F S S; Viana, N B; Nussenzveig, H M; Neto, P A Maia
2015-01-01
We propose to use optical tweezers to probe the Casimir interaction between microspheres inside a liquid medium for geometric aspect ratios far beyond the validity of the widely employed proximity force approximation. This setup has the potential for revealing unprecedented features associated to the non-trivial role of the spherical curvatures. For a proof of concept, we measure femtonewton double layer forces between polystyrene microspheres at distances above $400$ nm by employing very soft optical tweezers, with stiffness of the order of fractions of a fN/nm. As a future application, we propose to tune the Casimir interaction between a metallic and a polystyrene microsphere in saline solution from attraction to repulsion by varying the salt concentration. With those materials, the screened Casimir interaction may have a larger magnitude than the unscreened one. This line of investigation has the potential for bringing together different fields including classical and quantum optics, statistical physics an...
Direct simulation of critical Casimir forces
Hobrecht, Hendrik; Hucht, Alfred
2014-06-01
We present a new Monte Carlo method to calculate Casimir forces acting on objects in a near-critical fluid, considering the two basic cases of a wall and a sphere embedded in a two-dimensional Ising medium. During the simulation, the objects are moved through the system with appropriate statistical weights, and consequently are attracted or repelled from the system boundaries depending on the boundary conditions. The distribution function of the object position is utilized to obtain the residual free energy, or Casimir potential, of the configuration as well as the corresponding Casimir force. The results are in perfect agreement with known exact results. The method can easily be generalized to more complicated geometries, to higher dimensions, and also to colloidal suspensions with many particles.
Casimir Friction Force Between Polarizable Media
Høye, Johan S
2012-01-01
This work is a continuation of our recent series of papers on Casimir friction, for a pair of particles of low relative particle velocity. Each particle is modeled as a simple harmonic oscillator. Our basic method, as before, is the use of quantum mechanical statistical mechanics, involving the Kubo formula, at finite temperature. In this work we begin by analyzing the Casimir friction between two particles polarizable in all spatial directions, this being a generalization of our study in EPL 91, 60003 (2010), which was restricted to a pair of particles with longitudinal polarization only. For simplicity the particles are taken to interact via the electrostatic dipole-dipole interaction. Thereafter, we consider the Casimir friction between one particle and a dielectric half-space, and also the friction between two dielectric half-spaces. Finally, we consider general polarizabilities (beyond the simple one-oscillator form), and show how friction occurs at finite temperature when finite frequency regions of the...
Casimir-Polder Forces between Chiral Objects
Butcher, David T; Scheel, Stefan
2012-01-01
The chiral component of the Casimir-Polder potential is derived within the framework of macroscopic quantum electrodynamics. It is shown to exist only if the particle and the medium are both chiral. Furthermore, the chiral component of the Casimir-Polder potential can be attractive or repulsive, depending on the chirality of the molecule and the medium. The theory is applied to a cavity geometry in the non-retarded limit with the intention of enantiomer separation. For a ground state molecule the chiral component is dominated by the electric component and thus no explicit separation will happen. If the molecule is initially in an excited state the electric component of the Casimir-Polder force can be suppressed by an appropriate choice of material and the chiral component can select the molecule based on its chirality, allowing enantiomeric separation to occur.
Repulsive Casimir force between Weyl semimetals
Wilson, Justin H.; Allocca, Andrew A.; Galitski, Victor
2015-06-01
Weyl semimetals are a class of topological materials that exhibit a bulk Hall effect due to time-reversal symmetry breaking. We show that for the idealized semi-infinite case, the Casimir force between two identical Weyl semimetals is repulsive at short range and attractive at long range. Considering plates of finite thickness, we can reduce the size of the long-range attraction even making it repulsive for all distances when thin enough. In the thin-film limit, we study the appearance of an attractive Casimir force at shorter distances due to the longitudinal conductivity. Magnetic field, thickness, and chemical potential provide tunable nobs for this effect, controlling the Casimir force: whether it is attractive or repulsive, the magnitude of the effect, and the positions and existence of a trap and antitrap.
Dynamical Casimir effect and quantum cosmology
We apply the background field method and the effective action formalism to describe the four-dimensional dynamical Casimir effect. Our picture corresponds to the consideration of quantum cosmology for an expanding FRW universe (the boundary conditions act as a moving mirror) filled by a quantum massless GUT which is conformally invariant. We consider cases in which the static Casimir energy is attractive and repulsive. Inserting the simplest possible inertial term, we find, in the adiabatic (and semiclassical) approximation, the dynamical evolution of the scale factor and the dynamical Casimir stress analytically and numerically [for SU(2) super Yang-Mills theory]. Alternative kinetic energy terms are explored in the Appendix. (c) 2000 The American Physical Society
Dynamical Casimir effect with rough surfaces
Full text: The dynamical Casimir effect is a quantum vacuum effect that consists, essentially, in two related phenomena, namely: the particle creation due to moving neutral bodies and the radiation reaction forces that act on these bodies. Using simple arguments based on energy conservation, the emergence of a dissipative force on the moving bodies can be understood as the counterpart of the particle creation. Theoretical models for idealized plane surfaces, as for instance, an infinite plane metallic surface, are well known. However, real surfaces are necessarily rough so that this information must be somehow incorporated to the theoretical models. With this goal in mind, we first study the scattering of electromagnetic field modes by a rough and perfectly conducting mirror, using a perturbative method such that roughness is treated as a perturbation of the plane geometry. We calculate the modifications in the reflection coefficients due to roughness in first order of the corrugation amplitude. To be as general as possible, we consider the general case of a time-dependent corrugation. We then apply the obtained reflection coefficients to study dissipative effects in two distinct situations: a corrugated conducting surface moving laterally and a rotating rough conducting surface. We also show how to use the results for the electromagnetic field to derive the results for the case of a scalar field coupled to a rough surface which imposes on the field Dirichlet and Neumann boundary conditions. We show the necessity to go beyond the first order approximation and derive the reflection coefficients up to second order in the corrugation amplitude. We finish this work by showing some recent progress of second order calculations. (author)
Graphene Casimir Interactions and Some Possible Applications
Phan, Anh D.
Scientific development requires profound understandings of micromechanical and nanomechanical systems (MEMS/NEMS) due to their applications not only in the technological world, but also for scientific understanding. At the micro- or nano-scale, when two objects are brought close together, the existence of stiction or adhesion is inevitable and plays an important role in the behavior operation of these systems. Such effects are due to surface dispersion forces, such as the van der Waals or Casimir interactions. The scientific understanding of these forces is particularly important for low-dimensional materials. In addition, the discovery of materials, such as graphitic systems has provided opportunities for new classes of devices and challenging fundamental problems. Therefore, investigations of the van der Waals or Caismir forces in graphene-based systems, in particular, and the solution generating non-touching systems are needed. In this study, the Casimir force involving 2D graphene is investigated under various conditions. The Casimir interaction is usually studied in the framework of the Lifshitz theory. According to this theory, it is essential to know the frequency-dependent reflection coefficients of materials. Here, it is found that the graphene reflection coefficients strongly depend on the optical conductivity of graphene, which is described by the Kubo formalism. When objects are placed in vacuum, the Casimir force is attractive and leads to adhesion on the surface. We find that the Casimir repulsion can be obtained by replacing vacuum with a suitable liquid. Our studies show that bromobenzene is the liquid providing this effect. We also find that this long-range force is temperature dependent and graphene/bromobenzene/metal substrate configuration can be used to demonstrate merely thermal Casimir interaction at room temperature and micrometer distances. These findings would provide good guidance and predictions for practical studies.
Casimir forces beyond the proximity approximation
Bimonte, G; Jaffe, R L; Kardar, M
2011-01-01
The proximity force approximation (PFA) relates the interaction between closely spaced, smoothly curved objects to the force between parallel plates. Precision experiments on Casimir forces necessitate, and spur research on, corrections to the PFA. We use a derivative expansion for gently curved surfaces to derive the leading curvature modifications to the PFA. Our methods apply to any homogeneous and isotropic materials; here we present results for Dirichlet and Neumann boundary conditions and for perfect conductors. A Pad\\'e extrapolation constrained by a multipole expansion at large distance and our improved expansion at short distances, provides an accurate expression for the sphere-plate Casimir force at all separations.
Nonequilibrium Tuning of the Thermal Casimir Effect
Dean, David S; Maggs, A C; Podgornik, Rudolf
2016-01-01
In net-neutral systems correlations between charge fluctuations generate strong attractive thermal Casimir forces and engineering these forces to optimize nanodevice performance is an important challenge. We show how the normal and lateral thermal Casimir forces between two plates containing Brownian charges can be modulated by decorrelating the system through the application of an electric field, which generates a nonequilibrium steady state with a constant current in one or both plates, reducing the ensuing fluctuation-generated normal force while at the same time generating a lateral drag force. This hypothesis is confirmed by detailed numerical simulations as well as an analytical approach based on stochastic density functional theory.
Demonstration of the lateral casimir force.
Chen, F; Mohideen, U; Klimchitskaya, G L; Mostepanenko, V M
2002-03-11
The lateral Casimir force between a sinusoidally corrugated gold coated plate and large sphere was measured for surface separations between 0.2 to 0.3 microm using an atomic force microscope. The measured force shows the required periodicity corresponding to the corrugations. It also exhibits the necessary inverse fourth power distance dependence. The obtained results are shown to be in good agreement with a complete theory taking into account the imperfectness of the boundary metal. This demonstration opens new opportunities for the use of the Casimir effect for lateral translation in microelectromechanical systems. PMID:11909341
Does the Casimir force need corrections?
Altaisky, Mikhail
2011-01-01
The Casimir force $\\cF = -\\frac{\\pi^2\\hbar c}{240a^4}$, which attracts to each other two perfectly conducting parallel plates separated by the distance $a$ in vacuum, is one of the blueprints of the reality of vacuum fluctuations. Following the recent conjecture, that quantum fields should be described in terms of the fields depending on the resolution of measurement, rather than the position alone (M.V.Altaisky, Phys. Rev. D 81(2010)125003), we derive the correction to the Casimir energy depending on the ratio of the plate displacement amplitude to the distance between plates.
Repulsive Casimir Force between Dielectric Planes
Wetz, Karen Windmeier
2001-01-01
In 1948 H.B.G.Casimir predicted that an attractive force between two perfectly conducting neutral plates exists due to changes in the electromagnetic vacuum energy caused by the influence of the plates. In 1956 E.M. Lifshitz derived an extension of Casimir's expression applicable to finite temperatures and arbitrary dielectric constants for the two half-spaces and the gap in between them. It is shown in this brief report that, while the Lifshitz formula predicts an attractive force for the ca...
Casimir Forces between Nanoparticles and Substrates
Román-Velázquez, C E; Villarreal, C; Esquivel-Sirvent, R; Noguez, Cecilia
2002-01-01
We study the Casimir force between a nanoparticle and a substrate. We consider the interaction of metal nanoparticles with different substrates within the dipolar approximation. We study the force as a function of the distance for gold and potassium spheres, which are over a substrate of titanium dioxide, sapphire and a perfect conductor. We show that Casimir force is important in systems at the nanometer scale. We study the force as a function of the material properties, radii of the spheres, and the distance between the sphere and the substrate.
Casimir Force Between Quantum Plasmas
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)
``Casimir effect'' with active swimmers
Ray, Dipanjan; Lopatina, Lena; Olson Reichhardt, Cynthia; Reichhardt, Charles
2014-03-01
In recent years, active matter has increasingly found applications in nanoengineering.[1] Here we show using molecular dynamics simulations that the natural motion of ``run-and-tumble'' bacteria will push together two parallel walls arranged in a Casimir geometry. This effect is robust as long as the wall separation is comparable to or smaller than the bacterial run-length, so that the bacterial motion is not Brownian on the length scale of the walls. The magnitude of the attractive force between the walls exhibits an unusual exponential dependence on the wall separation. The attraction arises from a depleted concentration of bacteria in the region between the plates; this is caused by the tendency of the bacteria to slide along the walls, which breaks time-reversal symmetry and allows a density difference to develop. The same mechanism was used recently to explain bacterial rectification.[2] The inclusion of steric interactions between the bacteria reduces the attraction between the plates but does not eliminate it.
Change in the Casimir force between semiconductive bodies by irradiation
Inui, Norio [Graduate School of Engineering, University of Hyogo, 2167, Shosha, Himeji, Hyogo, 671-2280 (Japan)
2007-11-15
Two topics relevant to the Casimir force (retarded van der Waals force), which is exerted between neutral objects due to the quantum vacuum fluctuations of the electromagnetic field are discussed- First, the enhancement of the Casimir between silicon plates by irradiation is considered. Irradiation generates free carriers inside silicon and it can cause enhancement of the Casimir force between silicon membranes. The temporal behavior of the Casimir force between two parallel silicon membranes after irradiating the surface with UV pulse laser is numerically studied. Based on the Lifshitz theory accounting for thickness of the slabs, the Casimir force as a function of time and the finite size effect of the thickness is calculated. The our experiment in progress to demonstrate the enhancement of the Casimir force by irradiation is also refer. Second, the influence of optical adsorption on the Casimir force acting between a metallic sphere and a semiconductive plate illuminated with Gaussian light beam is considered. The Casimir torque and the lateral Casimir force result form the inhomogeneous photonionization. Taking into account the spatial inhomogeneousness of the plasma frequency in the semiconductive plate, the dependence of the Casimir force on the distance between the optical axis and the center of the sphere is computed within the proximity force approximation.
Change in the Casimir force between semiconductive bodies by irradiation
Two topics relevant to the Casimir force (retarded van der Waals force), which is exerted between neutral objects due to the quantum vacuum fluctuations of the electromagnetic field are discussed- First, the enhancement of the Casimir between silicon plates by irradiation is considered. Irradiation generates free carriers inside silicon and it can cause enhancement of the Casimir force between silicon membranes. The temporal behavior of the Casimir force between two parallel silicon membranes after irradiating the surface with UV pulse laser is numerically studied. Based on the Lifshitz theory accounting for thickness of the slabs, the Casimir force as a function of time and the finite size effect of the thickness is calculated. The our experiment in progress to demonstrate the enhancement of the Casimir force by irradiation is also refer. Second, the influence of optical adsorption on the Casimir force acting between a metallic sphere and a semiconductive plate illuminated with Gaussian light beam is considered. The Casimir torque and the lateral Casimir force result form the inhomogeneous photonionization. Taking into account the spatial inhomogeneousness of the plasma frequency in the semiconductive plate, the dependence of the Casimir force on the distance between the optical axis and the center of the sphere is computed within the proximity force approximation
Allard, T.; Fourdrin, C.; Calas, G.
2007-05-01
Understanding the processes controlling migrations of radioelements at the Earth's surface is an important issue for the long-term safety assessment of high level nuclear waste repositories (HLNWR). Evidence of past occurrence and transfer of radionuclides can be found using radiation-induced defects in minerals. Clay minerals are particularly relevant because of their widespread occurrence at the Earth's surface and their finely divided nature which provides high contact area with radioactive fluids. Owing to its sensitivity to radiations, kaolinite can be used as natural, in situ dosimeter. Kaolinite is known to contain radiation-induced defects which are detected by Electron Paramagnetic Resonance. They are differentiated by their nature, their production kinetics and their thermal stability. One of these defects is stable at the scale of geological periods and provides a record of past radionuclide occurrence. Based on artificial irradiations, a methodology has been subsequently proposed to determine paleodose cumulated by kaolinite since its formation. The paleodose can be used to derive equivalent radioelement concentrations, provided that the age of kaolinite formation can be constrained. This allows quantitative reconstruction of past transfers of radioelements in natural systems. An example is given for the Nopal I U-deposit (Chihuahua, Mexico), hosted in hydrothermally altered volcanic tufs and considered as analogue of the Yucca Mountain site. The paleodoses experienced by kaolinites were determined from the concentration of defects and dosimetry parameters of experimental irradiations. Using few geochemical assumption, a equivalent U-content responsible for defects in kaolinite was calculated from the paleodose, a dose rate balance and model ages of kaolinites constrained by tectonic phases. In a former study, the ages were assumptions derived from regional tectonic events. In thepresent study, ages of mineralization events are measured from U
Casimir stress on lossy magnetodielectric spheres
Raabe, C; Welsch, D G; Raabe, Christian; Knoell, Ludwig; Welsch, Dirk-Gunnar
2003-01-01
An expression for the Casimir stress on arbitrary dispersive and lossy linear magnetodielectric matter at finite temperature, including left-handed material, is derived and applied to spherical systems. To cast the relevant part of the scattering Green tensor for a general magnetodielectric sphere in a convenient form, classical Mie scattering is reformulated.
Casimir Energy of a Long Wormhole Throat
Butcher, Luke M
2014-01-01
We calculate the Casimir energy-momentum tensor induced in a scalar field by a macroscopic ultrastatic spherically-symmetric long-throated traversable wormhole, and examine whether this exotic matter is sufficient to stabilise the wormhole itself. The Casimir energy-momentum tensor is obtained (within the $\\mathbb{R}\\times S_2$ throat) by a mode sum approach, using a sharp energy cut-off and the Abel-Plana formula; Lorentz invariance is then restored by use of a Pauli-Villars regulator. The massless conformally-coupled case is found to have a logarithmic divergence (which we renormalise) and a conformal anomaly, the thermodynamic relevance of which is discussed. Provided the throat radius is above some fixed length, the renormalised Casimir energy-density is seen to be negative by all timelike observers, and almost all null rays; furthermore, it has sufficient magnitude to stabilise a long-throated wormhole far larger than the Planck scale, at least in principle. Unfortunately, the renormalised Casimir energy...
Observation of the thermal Casimir force
Sushkov, A O; Dalvit, D A R; Lamoreaux, S K
2010-01-01
Quantum theory predicts the existence of the Casimir force between macroscopic bodies, due to the zero-point energy of electromagnetic field modes around them. This quantum fluctuation-induced force has been experimentally observed for metallic and semiconducting bodies, although the measurements to date have been unable to clearly settle the question of the correct low-frequency form of the dielectric constant dispersion (the Drude model or the plasma model) to be used for calculating the Casimir forces. At finite temperature a thermal Casimir force, due to thermal, rather than quantum, fluctuations of the electromagnetic field, has been theoretically predicted long ago. Here we report the experimental observation of the thermal Casimir force between two gold plates. We measured the attractive force between a flat and a spherical plate for separations between 0.7 $\\mu$m and 7 $\\mu$m. An electrostatic force caused by potential patches on the plates' surfaces is included in the analysis. The experimental resul...
Repulsive Casimir Force in Chiral Metamaterials
Zhao, R.; Zhou, J.; Koschny, Th.; Economou, E.N.; Soukoulis, C.M.
2009-09-04
We demonstrate theoretically that one can obtain repulsive Casimir forces and stable nanolevitations by using chiral metamaterials. By extending the Lifshitz theory to treat chiral metamaterials, we find that a repulsive force and a minimum of the interaction energy possibly exist for strong chirality, under realistic frequency dependencies and correct limiting values (for zero and infinite frequencies) of the permittivity, permeability, and chiral coefficients.
Casimir force in Schwarzschild metric: Progress report
Karim, Munawar
2016-01-01
In this paper I report progress on both theoretical and experimental aspects. I describe two approaches to calculating putative effects of gravitational curvature on the Casimir force. The work I describe continues the quest to answer the question: do virtual field excitations follow geodesics?
Repulsive Casimir Force in Chiral Metamaterials
Zhao, R.; Zhou, J.; Koschny, Th.; Economou, E. N.; Soukoulis, C. M.
2009-01-01
We demonstrate theoretically that one can obtain repulsive Casimir forces and stable nanolevitations by using chiral metamaterials. By extending the Lifshitz theory to treat chiral metamaterials, we find that a repulsive force and a minimum of the interaction energy exist for strong chirality, under realistic frequency dependencies and correct limiting values (for zero and infinite frequencies) of the permittivity, permeability, and chiral coefficients.
Casimir forces in systems near jamming
Burton, Justin; Liétor-Santos, Juan-José
Casimir forces arise when long-ranged fluctuations are geometrically confined between two surfaces. In most cases these fluctuations are quantum or thermal in nature, such as those near a classical critical point, yet this is not a requirement. The T = 0 jamming transition in frictionless, granular systems shares many properties with classical critical points, such as a diverging correlation length, although it has recently been identified as a unique example of a random first-order transition (RFOT). Here we show the existence of Casimir forces between two pinned particles immersed in systems near the frictionless jamming transition. We observe two components to the total force: a short-ranged, depletion force and a long-ranged, repulsive Casimir force. The Casimir force dominates when the pinned particles are much larger than the ambient jammed particles. In this case, we find that particles with the largest forces have the least number of contacts, and that these particles are clustered between the pinned particles, giving rise to a repulsive force which is independent of system preparation and inter-particle potential. We acknowledge support from NSF DMR-1455086.
Casimir force between doped silicon slabs
Duraffourg, Laurent [Laboratoire des Composants Microsystemes, CEA/LETI 17 rue des Martyrs, 38054 Grenoble Cedex 9 (France)]. E-mail: laurent.duraffourg@cea.fr; Andreucci, Philippe [Laboratoire des Composants Microsystemes, CEA/LETI 17 rue des Martyrs, 38054 Grenoble Cedex 9 (France)]. E-mail: philippe.andreucci@cea.fr
2006-12-04
We evaluate the Casimir force for the particular case of silicon material including mirror thickness impact and finite conductivity influence. We show a new interesting behavior related to the slab thickness. We compare the results for intrinsic and doped silicon with traditional metals such as gold.
Cubic terms from Casimir invariants in IBM
The Xe and Ba nuclei have been shown to be good examples of O(6) dynamical symmetry of IBM. In particular, one might hope to construct cubic terms out of the Casimir invariants of the groups and subgroups of O(6), U(5) SU(3) which may give rise to triaxiality
Casimir apparatuses in a weak gravitational field
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...
Quantum simulation of the dynamical Casimir effect with trapped ions
Trautmann, N.; Hauke, P.
2016-04-01
Quantum vacuum fluctuations are a direct manifestation of Heisenberg’s uncertainty principle. The dynamical Casimir effect (DCE) allows for the observation of these vacuum fluctuations by turning them into real, observable photons. However, the observation of this effect in a cavity QED experiment would require the rapid variation of the length of a cavity with relativistic velocities, a daunting challenge. Here, we propose a quantum simulation of the DCE using an ion chain confined in a segmented ion trap. We derive a discrete model that enables us to map the dynamics of the multimode radiation field inside a variable-length cavity to radial phonons of the ion crystal. We perform a numerical study comparing the ion-chain quantum simulation under realistic experimental parameters to an ideal Fabry–Perot cavity, demonstrating the viability of the mapping. The proposed quantum simulator, therefore, allows for probing the photon (respectively phonon) production caused by the DCE on the single photon level.
Casimir-Lifshitz force out of thermal equilibrium
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 coming from the propagating and evanescent components of the electromagnetic radiation is performed. The large distance behaviors of such interactions is discussed, and both analytical and numerical results are compared with the equilibrium ones. A detailed analysis of the crossing between the surface-surface and the surface-rarefied body, and finally the surface-atom force is shown, and a complete derivation and discussion of the recently predicted nonadditivity effects and asymptotic behaviors is presented
The Casimir Effect in Relativistic Quantum Field Theories
Mostepanenko, V M
2008-01-01
We review recent developments in the Casimir effect which arises in quantization volumes restricted by material boundaries and in spaces with non-Euclidean topology. The starting point of our discussion is the novel exact solution for the electromagnetic Casimir force in the configuration of a cylinder above a plate. The related work for the scalar Casimir effect in sphere-plate configuration is also considered, and the application region of the proximity force theorem is discussed. Next we consider new experiments on the measurement of the Casimir force between metals and between metal and semiconductor. The complicated problem connected with the theory of the thermal Casimir force between real metals is analyzed in detail. The present situation regarding different theoretical approaches to the resolution of this problem is summarized. We conclude with new constraints on non-Newtonian gravity obtained using the results of latest Casimir force measurements and compare them with constraints following from the ...
Why are Casimir energy differences so often finite?
Visser, Matt
2016-01-01
One of the very first applications of the quantum field theoretic vacuum state was in the development of the notion of Casimir energy. Now field theoretic Casimir energies, considered individually, are always infinite. But differences in Casimir energies are quite often finite --- a fortunate circumstance which luckily made some of the early calculations, (for instance, for parallel plates and hollow spheres), tolerably tractable. We shall explore the extent to which this observation can be systematised. For instance: What are necessary and sufficient conditions for Casimir energy differences to be finite? When the Casimir energy differences are not finite, can anything useful be said? We shall see that it is the difference in the first few Seeley-DeWitt coefficients that is central to answering these questions. In particular, for any collection of conductors (perfect or imperfect) and/or dielectrics, as long as one merely moves them around without changing shape or volume, then the Casimir energy difference ...
Casimir energies of cavities: The geometry question
Abalo, Iroko Komi Elom
The question of how the Casimir effect relates to a system's geometry is of fundamental interest. In this thesis, we present new results for interior Casimir self-energies of various integrable geometries and show interesting systematic relations between these energies. In particular, we consider prisms with triangular cross sections (equilateral, hemiequilateral, and right isosceles triangles), triangular polygons of the same cross sections, and three tetrahedra. The triangular prisms are of infinite or finite lengths. These geometries are integrable and unique in the sense that the Laplacian eigenvalues may be found using the method of images. We obtain interior Casimir energies for these cavities subject to Dirichlet and Neumann boundary conditions. In addition to these boundary conditions, we also obtain electromagnetic Casimir energies for the infinite prisms. These energies are regularized using various consistent methods, one of which is regularization by point-splitting. Summing these modes explicitly using a cylinder kernel formulation, we show that the correct Weyl divergences are obtained. We also give closed-form results for the infinite triangular prisms. In order to understand the geometry dependence of these energies, we rederive well-known results for rectangular parallelepipeds (including the cube) and infinite rectangular prisms. The analysis of these self-energies yields intriguing results. By plotting the scaled energies against the appropriately chosen isoperimetric or isoareal quotients, we observe interesting patterns, which hint towards a systematic functional dependence. In addition to the calculation of new Casimir energies, this constitutes a significant contribution to the theoretical understanding of self-energies and has interesting implications.
Fermionic Casimir energy in a three-dimensional box
In this paper we calculate the Casimir energy for a massless fermionic field confined inside a three-dimensional rectangular box. We use the MIT bag model boundary condition for the confinement. We use the direct mode summation method along with the Abel-Plana summation formula to compute the Casimir energy, without any use of regularization or analytic continuation techniques. We obtain a negative Casimir energy, as opposed to the previously reported result for the interior of a three-dimensional sphere.
New features of the thermal Casimir force at small separations.
Chen, F; Klimchitskaya, G L; Mohideen, U; Mostepanenko, V M
2003-04-25
The difference of the thermal Casimir forces at different temperatures between real metals is shown to increase with a decrease of the separation distance. This opens new opportunities for the demonstration of the thermal dependence of the Casimir force. Both configurations of two parallel plates and a sphere above a plate are considered. Different approaches to the theoretical description of the thermal Casimir force are shown to lead to different measurable predictions. PMID:12731963
Optical detection of the Casimir force between macroscopic objects.
Petrov, Victor; Petrov, Mikhail; Bryksin, Valeriy; Petter, Juergen; Tschudi, Theo
2006-11-01
We report the optical detection of mechanical deformation of a macroscopic object induced by the Casimir force. An adaptive holographic interferometer based on a photorefractive BaTiO3:Co crystal was used to measure periodical nonlinear deformations of a thin pellicle caused by an oscillating Casimir force. A reasonable agreement between the experimental and calculated values of the first and second harmonics of the Casimir force oscillations has been obtained. PMID:17041670
Casimir force in the presence of a magnetodielectric medium
Kheirandish, Fardin; Sarabadani, Jalal
2010-01-01
In this article we investigate the Casimir effect in the presence of a medium by quantizing the Electromagnetic (EM) field in the presence of a magnetodielectric medium by using the path integral formalism. For a given medium with definite electric and magnetic susceptibilities, explicit expressions for the Casimir force are obtained which are in agree with the original Casimir force between two conducting parallel plates immersed in the quantum electromagnetic vacuum.
Matter-field theory of the Casimir force
Koashi, Masato; Ueda, Masahito
1998-01-01
A matter-field theory of the Casimir force is formulated in which the electromagnetic field and collective modes of dielectric media are treated on an equal footing. In our theory, the Casimir force is attributed to zero-point energies of the combined matter-field modes. We analyze why some of the existing theories favor the interpretation of the Casimir force as originating from zero-point energies of the electromagnetic field and others from those of the matter.
On the Relation Between Casimir Forces and Bulk Correlations
Napiórkowski, Marek; Piasecki, Jarosław
2014-09-01
Within a microscopic approach we show that in the case of an ideal quantum gas enclosed in a slit the Casimir force can be simply expressed in terms of the bulk one-particle density matrix. The corresponding formula, which holds both for bosons and fermions, allows to relate the range of the Casimir force to the bulk correlation length. The low-temperature behavior of the Casimir forces is derived.
Casimir Force in Non-Planar Geometric Configurations
Cho, Sung Nae
2004-01-01
The Casimir force for charge-neutral, perfect conductors of non-planar geometric configurations have been investigated. The configurations were: (1) the plate-hemisphere, (2) the hemisphere-hemisphere and (3) the spherical shell. The resulting Casimir forces for these physical arrangements have been found to be attractive. The repulsive Casimir force found by Boyer for a spherical shell is a special case requiring stringent material property of the sphere, as well as the specific boundary ...
Casimir force on an interacting Bose-Einstein condensate
Biswas, Shyamal; Majumder, Dwipesh; Saha, Kush [Department of Theoretical Physics, Indian Association for the Cultivation of Science, Jadavpur, Kolkata 700032 (India); Bhattacharjee, J K [S.N. Bose National Centre for Basic Sciences, Sector 3, JD Block, Salt Lake, Kolkata 700098 (India); Chakravarty, Nabajit, E-mail: tpsb2@iacs.res.i [Positional Astronomy Centre, Block AQ, Plot 8, Sector 5, Salt Lake, Kolkata 700091 (India)
2010-04-28
We have presented an analytic theory for the Casimir force on a Bose-Einstein condensate which is confined between two parallel plates. We have considered Dirichlet boundary conditions for the condensate wavefunction as well as for the phonon field. We have shown that the condensate wavefunction (which obeys the Gross-Pitaevskii equation) is responsible for the mean field part of the Casimir force, which usually dominates over the quantum (fluctuations) part of the Casimir force.
Casimir force on interacting Bose-Einstein condensate
Biswas, Shyamal; Bhattacharjee, J K; Majumder, Dwipesh; Saha, Kush; Chakravarty, Nabajit
2009-01-01
We have presented an analytic theory for the Casimir force on a Bose-Einstein condensate (BEC) which is confined between two parallel plates. We have considered Dirichlet boundary conditions for the condensate wave function as well as for the phonon field. We have shown that, the condensate wave function (which obeys the Gross-Pitaevskii equation) is responsible for the mean field part of Casimir force, which usually dominates over the quantum (fluctuations) part of the Casimir force.
Intermolecular Casimir-Polder forces in water and near surfaces
Thiyam, Priyadarshini; Persson, Clas; Sernelius, Bo E.; Parsons, Drew F.; Malthe-Sørenssen, Anders; Boström, Mathias
2014-09-01
The Casimir-Polder force is an important long-range interaction involved in adsorption and desorption of molecules in fluids. We explore Casimir-Polder interactions between methane molecules in water, and between a molecule in water near SiO2 and hexane surfaces. Inclusion of the finite molecular size in the expression for the Casimir-Polder energy leads to estimates of the dispersion contribution to the binding energies between molecules and between one molecule and a planar surface.
New Challenges and Directions in Casimir Force Experiments
Iannuzzi, Davide; Gelfand, Ian; Lisanti, Mariangela; Capasso, Federico
2003-01-01
This article is divided in three sections. In the first section we briefly review some high precision experiments on the Casimir force, underlying an important aspect of the analysis of the data. In the second section we discuss our recent results in the measurement of the Casimir force using non-trivial materials. In the third section we present some original ideas for experiments on new phenomena related to the Casimir effects.
Electrodynamic Casimir Effect in a Medium-Filled Wedge II
Ellingsen, Simen Adnoy; Brevik, Iver; Milton, Kimball A.
2009-01-01
We consider the Casimir energy in a geometry of an infinite magnetodielectric wedge closed by a circularly cylindrical, perfectly conducting arc embedded in another magnetodielectric medium, under the condition that the speed of light be the same in both media. An expression for the Casimir energy corresponding to the arc is obtained and it is found that in the limit where the reflectivity of the wedge boundaries tends to unity the finite part of the Casimir energy of a perfectly conducting w...
All-optical dynamical Casimir effect in a three-dimensional terahertz photonic band gap
Hagenmüller, David
2016-06-01
We identify an architecture for the observation of all-optical dynamical Casimir effect in realistic experimental conditions. We suggest that by integrating quantum wells in a three-dimensional (3D) photonic band-gap material made out of large-scale (˜200 -μ m ) germanium logs, it is possible to achieve ultrastrong light-matter coupling at terahertz frequencies for the cyclotron transition of a two-dimensional electron gas interacting with long-lived optical modes, in which vacuum Rabi splitting is comparable to the Landau level spacing. When a short, intense electromagnetic transient of duration ˜250 fs and carrying a peak magnetic field ˜5 T is applied to the structure, the cyclotron transition can be suddenly tuned on resonance with a desired photon mode, switching on the light-matter interaction and leading to a Casimir radiation emitted parallel to the quantum well plane. The radiation spectrum consists of sharp peaks with frequencies coinciding with engineered optical modes within the 3D photonic band gap, and its characteristics are extremely robust to the nonradiative damping which can be large in our system. Furthermore, the absence of continuum with associated low-energy excitations for both electromagnetic and electronic quantum states can prevent the rapid absorption of the photon flux which is likely to occur in other proposals for all-optical dynamical Casimir effect.
Distinguishing de Sitter universe from thermal Minkowski spacetime by Casimir-Polder-like force
Tian, Zehua
2014-01-01
Using the open quantum system approach, we demonstrate that the static ground state atom, which interacts with a conformally coupled massless scalar field in the de Sitter invariant vacuum, can obtain a position-dependent energy-level shift and this shift could cause a Casimir-Polder-like force on it. Interestingly no such force arises on the inertial atom bathed in a thermal radiation in the Minkowski universe. Thus, although the energy-level shifts of the static atom for these two cases are structurally the same, whether the energy-level shift causes the Casimir-Polder-like force, in principle, could be as an indicator to distinguish de Sitter universe from the thermal Minkowski spacetime.
Aharonov-Bohm phases and Dynamical Casimir Effect in a quantum LC circuit
Yao, Yuan
2016-01-01
We study novel types of contributions to the partition function of the Maxwell system defined on a small compact manifold ${\\mathbb{M}}$ with nontrivial mappings $\\pi_1[U(1)]\\cong\\mathbb{Z}$. These novel contributions cannot be described in terms of conventional physical propagating photons with two transverse polarizations, and instead emerge as a result of tunneling transitions between topologically different but physically identical vacuum winding states. These new terms give an extra contribution to the Casimir pressure, yet to be measured. We argue that if the same system is considered in the background of a small external time-dependent E\\&M field, then real physical photons will be emitted from the vacuum, similar to the dynamical Casimir effect (DCE) where photons are radiated from the vacuum due to time-dependent boundary conditions. We propose an experimental realization of such small effects using a microwave cavity. We also comment on the possible cosmological implications of this effect.
Optical and Casimir effects in topological materials
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
Matter-screened Casimir force and Casimir-Polder force in planar structures
Raabe, C; Raabe, Christian; Welsch, Dirk-Gunnar
2005-01-01
Using a recently developed theory of the Casimir force (Raabe C and Welsch D-G 2005 Phys. Rev. A 71 013814), we calculate the force that acts on a plate in front of a planar wall and the force that acts on the plate in the case where the plate is part of matter that fills the space in front of the wall. We show that in the limit of a dielectric plate whose permittivity is close to unity, the force obtained in the former case reduces to the ordinary, i.e., unscreened Casimir-Polder force acting on isolated atoms. In the latter case, the theory yields the Casimir-Polder force that is screened by the surrounding matter.
Matter-screened Casimir force and Casimir-Polder force in planar structures
Raabe, Christian; Welsch, Dirk-Gunnar [Theoretisch-Physikalisches Institut, Friedrich-Schiller-Universitaet Jena, Max-Wien-Platz 1, D-07743 Jena (Germany)
2005-12-01
Using a recently developed theory of the Casimir force (Raabe and Welsch 2005 Phys. Rev. A 71 013814), we calculate the force that acts on a plate in front of a planar wall and the force that acts on the plate in the case where the plate is part of matter that fills the space in front of the wall. We show that in the limit of a dielectric plate whose permittivity is close to unity, the force obtained in the former case reduces to the ordinary, i.e., unscreened, Casimir-Polder force acting on isolated atoms. In the latter case, the theory yields the Casimir-Polder force that is screened by the surrounding matter.
Matter-screened Casimir force and Casimir-Polder force in planar structures
Using a recently developed theory of the Casimir force (Raabe and Welsch 2005 Phys. Rev. A 71 013814), we calculate the force that acts on a plate in front of a planar wall and the force that acts on the plate in the case where the plate is part of matter that fills the space in front of the wall. We show that in the limit of a dielectric plate whose permittivity is close to unity, the force obtained in the former case reduces to the ordinary, i.e., unscreened, Casimir-Polder force acting on isolated atoms. In the latter case, the theory yields the Casimir-Polder force that is screened by the surrounding matter
CasimirSim - A Tool to Compute Casimir Polder Forces for Nontrivial 3D Geometries
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
Casimir Torque in Inhomogeneous Dielectric Plates
Long, William
2013-01-01
In this work, we consider a torque caused by the well known quantum mechanical Casimir effect arising from quantized field fluctuations between plates with inhomogeneous, sharply discontinuous, dielectric properties. While the Casimir effect is a relatively well understood phenomenon, systems resulting in lateral or rotational forces are far less developed; to our knowledge, a theoretical study of discontinuous dielectric variants of such systems has not been attempted. We utilize a Proximity Force Approximation in conjunction with the Lifshitz dielectric formula to perform theoretical analyses of resultant torques in systems with bisected and quadrisected dielectric regions. We also develop a high precision Monte Carlo type numerical integrator to approximate our derived expressions. Our calculations of an energy density linear with the alignment angle result in a constant torque and have implications in NEMS (nano electromechanical systems) and MEMS (micro electromechanical systems), including a postulated ...
Global Casimir Effect in the Schwarzschild Spacetime
Muniz, C R; Tahim, M O; Cunha, M S
2015-01-01
In this paper, we study the vacuum quantum fluctuations of an uncharged massive scalar field in the Schwarzschild background and analyze its main physical effects at zero temperature. The procedure consists of calculating the energy eigenvalues starting from the exact solutions recently found for the dynamics of that field, considering the regime in which the particle is not absorbed by the black hole. From this result, we obtain the vacuum energy for the field, taking into account the respective degeneracies. Then we use the Abel-Plana formula valid for bosonic fields in order to regularize this infinite vacuum energy. Such a regularized quantity is the Casimir energy, which is computed numerically and presented graphically. The Casimir energy thus obtained does not take into account any boundaries artificially imposed on the system, just the nontrivial spacetime topology associated to the source and its singularity.
The character of the supersymmetric Casimir energy
Martelli, Dario
2015-01-01
We study the supersymmetric Casimir energy $E_\\mathrm{susy}$ of $\\mathcal{N}=1$ field theories with an R-symmetry, defined on rigid supersymmetric backgrounds $S^1\\times M_3$, using a Hamiltonian formalism. These backgrounds admit an ambi-Hermitian geometry, and we show that the net contributions to $E_\\mathrm{susy}$ arise from certain twisted holomorphic modes on $\\mathbb{R}\\times M_3$, with respect to both complex structures. The supersymmetric Casimir energy may then be identified as a limit of an index-character that counts these modes. In particular this explains a recent observation relating $E_\\mathrm{susy}$ on $S^1\\times S^3$ to the anomaly polynomial. As further applications we compute $E_\\mathrm{susy}$ for certain secondary Hopf surfaces, and discuss how the index-character may also be used to compute generalized supersymmetric indices.
Extended Analysis of the Casimir Force
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.
Casimir force between sharp-shaped conductors
Maghrebi, Mohammad F; Emig, Thorsten; Graham, Noah; Jaffe, Robert L; Kardar, Mehran
2010-01-01
Casimir forces between conductors at the sub-micron scale cannot be ignored in the design and operation of micro-electromechanical (MEM) devices. However, these forces depend non-trivially on geometry, and existing formulae and approximations cannot deal with realistic micro-machinery components with sharp edges and tips. Here, we employ a novel approach to electromagnetic scattering, appropriate to perfect conductors with sharp edges and tips, specifically to wedges and cones. The interaction of these objects with a metal plate (and among themselves) is then computed systematically by a multiple-scattering series. For the wedge, we obtain analytical expressions for the interaction with a plate, as functions of opening angle and tilt, which should provide a particularly useful tool for the design of MEMs. Our result for the Casimir interactions between conducting cones and plates applies directly to the force on the tip of a scanning tunneling probe; the unexpectedly large temperature dependence of the force ...
Conformal field theory of critical Casimir forces
Emig, Thorsten; Bimonte, Giuseppe; Kardar, Mehran
2015-03-01
Thermal fluctuations of a critical system induce long-ranged Casimir forces between objects that couple to the underlying field. For two dimensional conformal field theories (CFT) we derive exact results for the Casimir interaction for a deformed strip and for two compact objects of arbitrary shape in terms of the free energy of a standard region (circular ring or flat strip) whose dimension is determined by the mutual capacitance of two conductors with the objects' shape; and a purely geometric energy that is proportional to conformal charge of the CFT, but otherwise super-universal in that it depends only on the shapes and is independent of boundary conditions and other details. The effect of inhomogenous boundary conditions is also discussed.
Casimir effect with rough metallic mirrors
We calculate the second-order roughness correction to the Casimir energy for two parallel metallic mirrors. Our results may also be applied to the plane-sphere geometry used in most experiments. The metallic mirrors are described by the plasma model, with arbitrary values for the plasma wavelength, the mirror separation, and the roughness correlation length, with the roughness amplitude remaining the smallest length scale for perturbation theory to hold. From the analysis of the intracavity field fluctuations, we obtain the Casimir energy correction in terms of generalized reflection operators, which account for diffraction and polarization coupling in the scattering by the rough surfaces. We present simple analytical expressions for several limiting cases, as well as numerical results that allow for a reliable calculation of the roughness correction in real experiments. The correction is larger than the result of the proximity force approximation, which is obtained from our theory as a limiting case (very smooth surfaces)
Curved Casimir Operators and the BGG Machinery
Andreas Cap
2007-11-01
Full Text Available We prove that the Casimir operator acting on sections of a homogeneous vector bundle over a generalized flag manifold naturally extends to an invariant differential operator on arbitrary parabolic geometries. We study some properties of the resulting invariant operators and compute their action on various special types of natural bundles. As a first application, we give a very general construction of splitting operators for parabolic geometries. Then we discuss the curved Casimir operators on differential forms with values in a tractor bundle, which nicely relates to the machinery of BGG sequences. This also gives a nice interpretation of the resolution of a finite dimensional representation by (spaces of smooth vectors in principal series representations provided by a BGG sequence.
Curved Casimir Operators and the BGG Machinery
Cap, Andreas; Soucek, Vladimír
2007-11-01
We prove that the Casimir operator acting on sections of a homogeneous vector bundle over a generalized flag manifold naturally extends to an invariant differential operator on arbitrary parabolic geometries. We study some properties of the resulting invariant operators and compute their action on various special types of natural bundles. As a first application, we give a very general construction of splitting operators for parabolic geometries. Then we discuss the curved Casimir operators on differential forms with values in a tractor bundle, which nicely relates to the machinery of BGG sequences. This also gives a nice interpretation of the resolution of a finite dimensional representation by (spaces of smooth vectors in) principal series representations provided by a BGG sequence.
Casimir-Lifshitz interaction between dielectric heterostructures
The interaction between arbitrary dielectric heterostructures is studied within the framework of a recently developed dielectric contrast perturbation theory. It is shown that periodically patterned dielectric or metallic structures lead to oscillatory lateral Casimir-Lifshitz forces, as well as modulations in the normal force as they are displaced with respect to one another. The strength of these oscillatory contributions increases with decreasing gap size and increasing contrast in the dielectric properties of the materials used in the heterostructures.
Casimir-Lifshitz interaction between dielectric heterostructures
Azari, Arash; Samanta, Himadri S; Golestanian, Ramin [Department of Physics and Astronomy, University of Sheffield, Sheffield S3 7RH (United Kingdom)], E-mail: r.golestanian@sheffield.ac.uk
2009-09-15
The interaction between arbitrary dielectric heterostructures is studied within the framework of a recently developed dielectric contrast perturbation theory. It is shown that periodically patterned dielectric or metallic structures lead to oscillatory lateral Casimir-Lifshitz forces, as well as modulations in the normal force as they are displaced with respect to one another. The strength of these oscillatory contributions increases with decreasing gap size and increasing contrast in the dielectric properties of the materials used in the heterostructures.
The Casimir effect and critical phenomena
In the present review we focus our attention on the theory and experimental confirmations of the Casimir effect in critical phenomena. Since the effect is related to the boundary conditions imposed on a system undergoing a phase transition and its consequences, the theory of critical phenomena in finite-size systems is an indispensable part of the theoretical description. Experiments with liquid films near a critical point are of particular experimental relevance to the studied phenomenon
Improved Precision Measurement of the Casimir Force
Roy, Anushree; Lin, Chiung-Yuan; Mohideen, U.
1999-01-01
We report an improved precision measurement of the Casimir force. The force is measured between a large Al coated sphere and flat plate using an Atomic Force Microscope. The primary experimental improvements include the use of smoother metal coatings, reduced noise, lower systematic errors and independent measurement of surface separations. Also the complete dielectric spectrum of the metal is used in the theory. The average statistical precision remains at the same 1% of the forces measured ...
Isotopic dependence of the Casimir force.
Krause, Dennis E; Fischbach, Ephraim
2002-11-01
We calculate the dependence of the Casimir force on the isotopic composition of the interacting objects. This dependence arises from the subtle influence of the nuclear masses on the electronic properties of the bodies. We discuss the relevance of these results to current experiments utilizing the isoelectronic effect to search at very short separations for new weak forces suggested by various unification theories. PMID:12443107
Casimir Force at a Knife's Edge
Graham, Noah; Shpunt, Alexander; Emig, Thorsten; Rahi, Sahand Jamal; Jaffe, Robert L.; Kardar, Mehran
2009-01-01
The Casimir force has been computed exactly for only a few simple geometries, such as infinite plates, cylinders, and spheres. We show that a parabolic cylinder, for which analytic solutions to the Helmholtz equation are available, is another case where such a calculation is possible. We compute the interaction energy of a parabolic cylinder and an infinite plate (both perfect mirrors), as a function of their separation and inclination, $H$ and $\\theta$, and the cylinder's parabolic radius $R...
Critical Casimir Force between Inhomogeneous Boundaries
Dubail, Jerome; Santachiara, Raoul; Emig, Thorsten
2015-01-01
To study the critical Casimir force between chemically structured boundaries immersed in a binary mixture at its demixing transition, we consider a strip of Ising spins subject to alternating fixed spin boundary conditions. The system exhibits a boundary induced phase transition as function of the relative amount of up and down boundary spins. This transition is associated with a sign change of the asymptotic force and a diverging correlation length that sets the scale for the crossover betwe...
A dispersive correction to the Casimir force
Ravndal, Finn; Teo, Lee-Peng
2010-01-01
Using perturbation theory the first order dispersive correction to the Casimir energy between two plates separated by a dielectric material is calculated. It falls off with the plate separation as 1/L^6. The result is derived both from evaluation of the zero-point energy and within the Lifshitz formulation. It is pointed out that a possible surface term can be more important, varying like 1/L^5.
Demonstration of the Lateral Casimir Force
Chen, F; Mohideen, U.; Klimchitskaya, G. L.; Mostepanenko, V. M.
2002-01-01
The lateral Casimir force between a sinusoidally corrugated gold coated plate and large sphere was measured for surface separations between 0.2 $\\mu$m to 0.3 $\\mu$m using an atomic force microscope. The measured force shows the required periodicity corresponding to the corrugations. It also exhibits the necessary inverse fourth power distance dependence. The obtained results are shown to be in good agreement with a complete theory taking into account the imperfectness of the boundary metal. T...
Repulsive Casimir force in chiral metamaterials.
Zhao, R; Zhou, J; Koschny, Th; Economou, E N; Soukoulis, C M
2009-09-01
We demonstrate theoretically that one can obtain repulsive Casimir forces and stable nanolevitations by using chiral metamaterials. By extending the Lifshitz theory to treat chiral metamaterials, we find that a repulsive force and a minimum of the interaction energy possibly exist for strong chirality, under realistic frequency dependencies and correct limiting values (for zero and infinite frequencies) of the permittivity, permeability, and chiral coefficients. PMID:19792309
Casimir force between integrable and chaotic pistons
Alvarez, Ezequiel; Mazzitelli, Francisco Diego; Monastra, Alejandro G.; Wisniacki, Diego A.
2010-01-01
We have computed numerically the Casimir force between two identical pistons inside a very long cylinder, considering different shapes for the pistons. The pistons can be considered as quantum billiards, whose spectrum determines the vacuum force. The smooth part of the spectrum fixes the force at short distances, and depends only on geometric quantities like the area or perimeter of the piston. However, correcting terms to the force, coming from the oscillating part of the spectrum which is ...
Casimir Friction Force for Moving Harmonic Oscillators
Høye, Johan S.; Brevik, Iver
2011-01-01
Casimir friction is analyzed for a pair of dielectric particles in relative motion. We first adopt a microscopic model for harmonically oscillating particles at finite temperature T moving non-relativistically with constant velocity. We use a statistical-mechanical description where time-dependent correlations are involved. This description is physical and direct, and, in spite of its simplicity, is able to elucidate the essentials of the problem. This treatment elaborates upon, and extends, ...
Casimir force between atomically thin gold films
Boström, Mathias; Persson, Clas; Sernelius, Bo E.
2013-01-01
We have used density functional theory to calculate the anisotropic dielectric functions for ultrathin gold sheets (composed of 1, 3, 6, and 15 atomic layers). Such films are important components in nano-electromechanical systems. When using correct dielectric functions rather than bulk gold dielectric functions we predict an enhanced attractive Casimir-Lifshitz force (at most around 20%) between two atomically thin gold sheets. For thicker sheets the dielectric properties and the correspondi...
Casimir force between sharp-shaped conductors
Maghrebi, Mohammad F.; Rahi, Sahand Jamal; Emig, Thorsten; Graham, Noah; Jaffe, Robert L.; Kardar, Mehran
2010-01-01
Casimir forces between conductors at the sub-micron scale cannot be ignored in the design and operation of micro-electromechanical (MEM) devices. However, these forces depend non-trivially on geometry, and existing formulae and approximations cannot deal with realistic micro-machinery components with sharp edges and tips. Here, we employ a novel approach to electromagnetic scattering, appropriate to perfect conductors with sharp edges and tips, specifically to wedges and cones. The interactio...
Probing the Casimir force with optical tweezers
Ether Jr, D. S.; Pires, L. B.; Umrath, S.; Martinez, D; Ayala, Y.; Pontes, B.; Araújo, G. R. de S.; Frases, S.; Ingold, G. -L.; Rosa, F. S. S.; Viana, N. B.; Nussenzveig, H. M.; Neto, P A Maia
2015-01-01
We propose to use optical tweezers to probe the Casimir interaction between microspheres inside a liquid medium for geometric aspect ratios far beyond the validity of the widely employed proximity force approximation. This setup has the potential for revealing unprecedented features associated to the non-trivial role of the spherical curvatures. For a proof of concept, we measure femtonewton double layer forces between polystyrene microspheres at distances above $400$ nm by employing very sof...
Casimir electromotive force in periodic configurations
Fateev, Evgeny G.
2016-01-01
The possibility in principle of the existence of Casimir electromotive force (EMF) is shown for nonparallel nanosized metal plates arranged in the form of a periodic structure. It is found that EMF does not appear in strictly periodic structures with parallel plates. However, when the strict periodicity is disturbed in nonparallel plates, EMF is generated, and its value is equal to the number of pairs of plates in a configuration. Moreover, there are some effective parameters of the configura...
The Scattering Approach to the Casimir Force
Reynaud, S.; Canaguier-Durand, A.; Messina, R; Lambrecht, A.; Neto, P A Maia
2010-01-01
We present the scattering approach which is nowadays the best tool for describing the Casimir force in realistic experimental configurations. After reminders on the simple geometries of 1d space and specular scatterers in 3d space, we discuss the case of stationary arbitrarily shaped mirrors in electromagnetic vacuum. We then review specific calculations based on the scattering approach, dealing for example with the forces or torques between nanostructured surfaces and with the force between ...
Sample dependence of the Casimir force
Svetovoy, V.B.
2004-01-01
Difference between bulk material and deposited film is shown to have an appreciable influence on the Casimir force. Analysis of the optical data on gold films unambiguously demonstrates the sample dependence: the dielectric functions of the films deposited in different conditions are different on the level that cannot be ignored in high precision prediction of the force. It is argued that the precise values of the Drude parameters are crucial for accurate evaluation of the force. The dielectr...
Isoelectronic determination of the thermal Casimir force
G. Bimonte; Lopez, D.; Decca, R. S.
2015-01-01
Differential force measurements between spheres coated with either nickel or gold and rotating disks with periodic distributions of nickel and gold are reported. The rotating samples are covered by a thin layer of titanium and a layer of gold. While titanium is used for fabrication purposes, the gold layer (nominal thicknesses of 21, 37, 47 and 87 nm) provides an isoelectronic environment, and is used to nullify the electrostatic contribution but allow the passage of long wavelength Casimir p...
Observation of the thermal Casimir force
Sushkov, A. O.; Kim, W. J.; Dalvit, D. A. R.; Lamoreaux, S. K.
2010-01-01
Quantum theory predicts the existence of the Casimir force between macroscopic bodies, due to the zero-point energy of electromagnetic field modes around them. This quantum fluctuation-induced force has been experimentally observed for metallic and semiconducting bodies, although the measurements to date have been unable to clearly settle the question of the correct low-frequency form of the dielectric constant dispersion (the Drude model or the plasma model) to be used for calculating the Ca...
Isotopic Dependence of the Casimir Force
Krause, Dennis E.; Fischbach, Ephraim
2002-01-01
We calculate the dependence of the Casimir force on the isotopic composition of the interacting objects. This dependence arises from the subtle influence of the nuclear masses on the electronic properties of the bodies. We discuss the relevance of these results to current experiments utilizing the iso-electronic effect to search at very short separations for new weak forces suggested by various unification theories.
The Casimir force at high temperature
Buenzli, P. R.; Martin, Ph. A.
2005-01-01
The standard expression of the high-temperature Casimir force between perfect conductors is obtained by imposing macroscopic boundary conditions on the electromagnetic field at metallic interfaces. This force is twice larger than that computed in microscopic classical models allowing for charge fluctuations inside the conductors. We present a direct computation of the force between two quantum plasma slabs in the framework of non relativistic quantum electrodynamics including quantum and ther...
The fermionic Casimir effect at finite temperature
Vacuum fluctuations of massless fermions between two parallel and confining plates give rise to an attractive Casimir force at zero temperature. It becomes repulsive at sufficiently high temperatures. All thermodynamic quantities are given by the free energy which satisfies a remarkable symmetry under temperature inversion. The fermion condensate varies between the plates and goes rapidly to zero with increasing temperature, except for a narrow region adjacent to the plates
Electromagnetic Casimir Forces in Elliptic Cylinder Geometries
Graham, Noah
2013-01-01
The scattering theory approach makes it possible to carry out exact calculations of Casimir energies in any geometry for which the scattering T-matrix and a partial wave expansion of the free Green's function are available. We implement this program for the case of a perfectly conducting elliptic cylinder, thereby completing the set of geometries where electromagnetic scattering is separable. Particular emphasis is placed on the case of zero radius, where the elliptic cylinder reduces to a st...
Casimir forces between cylinders at different temperatures
Golyk, Vladyslav A.; Krüger, Matthias; Reid, M. T. Homer; Kardar, Mehran
2012-01-01
We study Casimir interactions between cylinders in thermal non-equilibrium, where the objects as well as the environment are held at different temperatures. We provide the general formula for the force, in a one reflection approximation, for cylinders of arbitrary radii and optical properties. As is the case for equilibrium, we find that the force for optically diluted cylinders can be obtained by appropriate summation of the corresponding result for spheres. We find that the non-equilibrium ...
Matter-screened Casimir force and Casimir-Polder force in planar structures
Raabe, Christian; Welsch, Dirk-Gunnar
2005-01-01
Using a recently developed theory of the Casimir force (Raabe C and Welsch D-G 2005 Phys. Rev. A 71 013814), we calculate the force that acts on a plate in front of a planar wall and the force that acts on the plate in the case where the plate is part of matter that fills the space in front of the wall. We show that in the limit of a dielectric plate whose permittivity is close to unity, the force obtained in the former case reduces to the ordinary, i.e., unscreened Casimir-Polder force actin...
Casimir effect in de Sitter spacetime
Saharian, A A
2011-01-01
The vacuum expectation value of the energy-momentum tensor and the Casimir forces are investigated for a massive scalar field with an arbitrary curvature coupling parameter in the geometry of two parallel plates, on the background of de Sitter spacetime. The field is prepared in the Bunch--Davies vacuum state and is constrained to satisfy Robin boundary conditions on the plates. The vacuum energy-momentum tensor is non-diagonal, with the off-diagonal component corresponding to the energy flux along the direction normal to the plates. It is shown that the curvature of the background spacetime decisively influences the behavior of the Casimir forces at separations larger than the curvature radius of de Sitter spacetime. In dependence of the curvature coupling parameter and the mass of the field, two different regimes are realized, which exhibit monotonic or oscillatory behavior of the forces. The decay of the Casimir force at large plate separation is shown to be power-law, with independence of the value of the...
Casimir effect in dielectrics: Bulk energy contribution
In a recent series of papers, Schwinger discussed a process that he called the dynamical Casimir effect. The key essence of this effect is the change in zero-point energy associated with any change in a dielectric medium. (In particular, if the change in the dielectric medium is taken to be the growth or collapse of a bubble, this effect may have relevance to sonoluminescence.) The kernel of Schwinger close-quote s result is that the change in Casimir energy is proportional to the change in the volume of the dielectric, plus finite-volume corrections. Other papers have called into question this result, claiming that the volume term should actually be discarded, and that the dominant term remaining is proportional to the surface area of the dielectric. In this paper, which is an expansion of an earlier Letter on the same topic, we present a careful and critical review of the relevant analyses. We find that the Casimir energy, defined as the change in zero-point energy due to a change in the medium, has at leading order a bulk volume dependence. This is in full agreement with Schwinger close-quote s result, once the correct physical question is asked. We have nothing new to say about sonoluminescence itself. copyright 1997 The American Physical Society