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Dynamical Casimir-Polder force between an atom and a conducting wall  [PDF]
R. Vasile,R. Passante
Physics , 2008, DOI: 10.1103/PhysRevA.78.032108
Abstract: The time-dependent Casimir-Polder force arising during the time evolution of an initially bare two-level atom, interacting with the radiation field and placed near a perfectly conducting wall, is considered. Initially the electromagnetic field is supposed to be in the vacuum state and the atom in its ground state. The analytical expression of the force as a function of time and atom-wall distance, is evaluated from the the time-dependent atom-field interaction energy. Physical features and limits of validity of the results are discussed in detail.
Fluctuations of the Casimir-Polder force between an atom and a conducting wall  [PDF]
R. Messina,R. Passante
Physics , 2007, DOI: 10.1103/PhysRevA.76.032107
Abstract: We consider the quantum fluctuations of the Casimir-Polder force between a neutral atom and a perfectly conducting wall in the ground state of the system. In order to obtain the atom-wall force fluctuation we first define an operator directly associated to the force experienced by the atom considered as a polarizable body in an electromagnetic field, and we use a time-averaged force operator in order to avoid ultraviolet divergences appearing in the fluctuation of the force. This time-averaged force operator takes into account that any measurement involves a finite time. We also calculate the Casimir-Polder force fluctuation for an atom between two conducting walls. Experimental observability of these Casimir-Polder force fluctuations is also discussed, as well as the dependence of the relative force fluctuation on the duration of the measurement.
Casimir-Polder force density between an atom and a conducting wall  [PDF]
R. Messina,R. Passante
Physics , 2006, DOI: 10.1103/PhysRevA.75.042113
Abstract: In this paper we calculate the Casimir-Polder force density (force per unit area acting on the elements of the surface) on a metallic plate placed in front of a neutral atom. To obtain the force density we use the quantum operator associated to the electromagnetic stress tensor. We explicitly show that the integral of this force density over the plate reproduces the total force acting on the plate. This result shows that, although the force is obtained as a sum of surface element-atom contributions, the stress-tensor method includes also nonadditive components of Casimir-Polder forces in the evaluation of the force acting on a macroscopic object.
Electromagnetic field correlators, Maxwell stress tensor, and the Casimir effect for parallel walls
Santos, F. C.;Passos Sobrinho, J. J.;Tort, A. C.;
Brazilian Journal of Physics , 2005, DOI: 10.1590/S0103-97332005000400013
Abstract: we evaluate the quantum electromagnetic field correlators associated with the electromagnetic vacuum distorted by the presence of two plane parallel conducting walls and in the presence of a conducting wall parallel to a perfectly magnetically permeable one. regularization is performed through the generalized zeta funtion technique. results are applied to rederive the atractive and repulsive casimir effect through maxwell stress tensor. surface divergences are shown to cancel out when stresses on both sides of the material surface are taken into account.
Casimir-Polder interaction between an atom and a conducting wall in cosmic string spacetime  [PDF]
E. R. Bezerra de Mello,V. B. Bezerra,H. F. Mota,A. A. Saharian
Physics , 2012, DOI: 10.1103/PhysRevD.86.065023
Abstract: The Casimir-Polder interaction potential is evaluated for a polarizable microparticle and a conducting wall in the geometry of a cosmic string perpendicular to the wall. The general case of the anisotropic polarizability tensor for the microparticle is considered. The corresponding force is a function of the wall-microparticle and cosmic string-microparticle distances. Depending on the orientation of the polarizability tensor principal axes the force can be either attractive or repulsive. The asymptotic behavior of the Casimir-Polder potential is investigated at large and small separations compared to the wavelength of the dominant atomic transitions. We show that the conical defect may be used to control the strength and the sign of the Casimir-Polder force.
Quantum Statistical Properties of the Interactions of Atom-Field Entanglement between Conducting Plates  [PDF]
Eied Khalil
Journal of Modern Physics (JMP) , 2011, DOI: 10.4236/jmp.2011.27085
Abstract: The electromagnetic field inside perfectly conducting parallel plates interacting with two-level atom is investigated. The cavity modes are firstly quantized, allowing the effective Hamiltonian to be evaluated for an electric dipole located at an arbitrary point. Some statistical aspect of this effective Hamiltonian such as the temporal evolution of the atomic inversion and the von Neuman entropy are presented. Theses aspects are sensitive to the changes of the distance between the two plates, which control the number of the propagating of the cavity modes.
Moving Atom-Field Interaction: Correction to Casimir-Polder Effect from Coherent Back-action  [PDF]
S. Shresta,B. L. Hu,N. G. Phillips
Physics , 2003, DOI: 10.1103/PhysRevA.68.062101
Abstract: The Casimir-Polder force is an attractive force between a polarizable atom and a conducting or dielectric boundary. Its original computation was in terms of the Lamb shift of the atomic ground state in an electromagnetic field (EMF) modified by boundary conditions along the wall and assuming a stationary atom. We calculate the corrections to this force due to a moving atom, demanding maximal preservation of entanglement generated by the moving atom-conducting wall system. We do this by using non-perturbative path integral techniques which allow for coherent back-action and thus can treat non-Markovian processes. We recompute the atom-wall force for a conducting boundary by allowing the bare atom-EMF ground state to evolve (or self-dress) into the interacting ground state. We find a clear distinction between the cases of stationary and adiabatic motions. Our result for the retardation correction for adiabatic motion is up to twice as much as that computed for stationary atoms. We give physical interpretations of both the stationary and adiabatic atom-wall forces in terms of alteration of the virtual photon cloud surrounding the atom by the wall and the Doppler effect.
Interaction of Ultracold Antihydrogen with a Conducting Wall  [PDF]
A. Yu. Voronin,P. Froelich,B. Zygelman
Physics , 2006, DOI: 10.1103/PHYSREVA.72.062903
Abstract: We investigate the interaction of ultracold antihydrogen with a conducting surface. Our discussion focuses on the physical regime where the phenomenon of quantum reflection manifests. We calculate the reflection probability as function of incident atom energy. We find that, for ground state $\bar{H}$ atoms (with $T< 10^{-5}$ K), the probability of reflection is $R \simeq 1-k b$, where $k$ is the momentum of the atom and $b = 2174.0$ a.u. is a constant determined solely by the van der Waals-Casimir tail of the atom-wall interaction. We show that quantum reflection, which suppresses the direct contact of ultra-cold atoms with the surface, allows for the possibility of confinement and storage of cold antihydrogen atoms. We calculate the life-time of confinement as a function of antihydrogen energy. We develop a theory of $\bar{H}$ in a wave-guide and propose its application to fundamental measurements. In particular, for measurement of retardation corrections in the long-range component of the antiatom - wall potential. We demonstrate, for $\bar{H}$ falling in the gravitational field of Earth onto a conducting surface, the existence of quantized $\bar{H}$ states. We calculate that the lifetime of ultracold $\bar{H}$ in its lowest gravitational state and obtain $\tau=(Mg b/2\hbar)^{-1}\simeq 0.1$ s, where $Mg$ is a gravitational force acting on the antiatom. We propose that measurement of this lifetime may provide a new test for the gravitational properties of antimatter.
Eddy current damping of a moving domain wall: beyond the quasistatic approximation  [PDF]
Francesca Colaiori,Gianfranco Durin,Stefano Zapperi
Physics , 2007, DOI: 10.1103/PhysRevB.76.224416
Abstract: In conducting ferromagnetic materials, a moving domain wall induces eddy currents in the sample which give rise to an effective retarding pressure on the domain wall. We show here that the pressure is not just proportional to the instantaneous velocity of the wall, as often assumed in domain wall models, but depends on the history of the motion. We calculate the retarding pressure by solving the Maxwell equations for the field generated by the eddy currents, and show how its effect can be accounted for by associating a negative effective mass to the magnetic wall. We analyze the dependence of this effect on the sample geometry and discuss the implications for Barkhausen noise measurements.
Confined Maxwell Field and Temperature Inversion Symmetry  [PDF]
A. C. Tort,F. C. Santos
Physics , 2000, DOI: 10.1016/S0370-2693(00)00498-6
Abstract: We evaluate the Casimir vacuum energy at finite temperature associated with the Maxwell field confined by a perfectly conducting rectangular cavity and show that an extended version of the temperature inversion symmetry is present in this system.
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