We study single-and two-atom van der Waals interactions of ground-state atoms which are both polarizable and paramagnetizable in the presence of magnetoelectric bodies within the framework of macroscopic quantum electrodynamics. Starting from an interaction Hamiltonian that includes particle spins, we use leading-order perturbation theory to express the van der Waals potentials in terms of the polarizability and magnetizability of the atom(s). To allow for atoms embedded in media, we also include local-field corrections via the real-cavity model. The general theory is applied to the potential of a single atom near a half space and that of two atoms embedded in a bulk medium or placed near a sphere, respectively. PACS numbers: 34.35.+a,
We present a formula for the body-assisted van der Waals interaction potential between two atoms, one or both being prepared in an excited energy eigenstate. The presence of an arbitrary arrangement for a material environment is taken into account via the Green function. The resulting formula supports one of two conflicting findings recorded. The consistency of our formula is investigated by applying it for the case of two atoms in free space and comparing the resulting expression with the one found from the limiting Casimir-Polder potential between an excited atom and a small dielectric sphere.
Using fourth-order perturbation theory, a general formula for the van der Waals potential of two neutral, unpolarized, ground-state atoms in the presence of an arbitrary arrangement of dispersing and absorbing magnetodielectric bodies is derived. The theory is applied to two atoms in bulk material and in front of a planar multilayer system, with special emphasis on the cases of a perfectly reflecting plate and a semi-infinite half space. It is demonstrated that the enhancement and reduction of the two-atom interaction due to the presence of a perfectly reflecting plate can be understood, at least in the nonretarded limit, by using the method of image charges. For the semi-infinite half space, both analytical and numerical results are presented.Comment: 17 pages, 9 figure
We predict a discriminatory interaction between a chiral molecule and an achiral molecule which is mediated by a chiral body. To achieve this, we generalize the van der Waals interaction potential between two ground-state molecules with electric, magnetic and chiral response to non-trivial environments. The force is evaluated using second-order perturbation theory with an effective Hamiltonian. Chiral media enhance or reduce the free interaction via many-body interactions, making it possible to measure the chiral contributions to the van der Waals force with current technology. The van der Waals interaction is discriminatory with respect to enantiomers of different handedness and could be used to separate enantiomers. We also suggest a specific geometric configuration where the electric contribution to the van der Waals interaction is zero, making the chiral component the dominant effect.PACS numbers: 34.20. Cf, 33.55.+b,42.50.Nn Introduction. Casimir and van der Waals (vdW) forces are electromagnetic interactions between neutral macroscopic bodies and/or molecules due to the quantum fluctuations of the electromagnetic field [1][2][3]. In particular, the attractive vdW potential between two electrically polarisable particles was first derived by Casimir and Polder using the minimal-coupling Hamiltonian [2]. Molecules can also exhibit magnetic [4][5][6][7] and chiral polarisabilities [4,8,9] and their contribution to the vdW force can be repulsive.The aim of this work is the study of the interaction between chiral molecules in the presence of a chiral magneto-dielectric body. Chiral molecules lack any center of inversion nor plane of symmetry. Hence they exist as two distinct enantiomers, left-handed and righthanded, which are related to space inversion. Due to their low symmetry they have distinctive interactions with light. In a chiral solution the refractive indices for circularly polarized light of different handedness are different. Hence a chiral solution can rotate the plane of polarization of light with an angle related to the concentration of the solution (optical rotation) [10][11][12], or absorb left-and right-circularly polarised light at different rates (circular dichroism) [13]. All of these phenomena are related to the optical rotatory strength, defined in terms of electric (d nk ) and magnetic (m nk ) dipole moment matrix elements [14]:
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