Impact of anisotropy on the interaction of an atom with a one-dimensional nano-grating

Abstract

We study the interaction of an atom with a one-dimensional nanograting within the framework of macroscopic QED, with special emphasis on possible anisotropic contributions. To this end, we first derive the scattering Green's tensor of the grating by means of a Rayleigh expansion and discuss its symmetry properties and asymptotes. We then determine the Casimir-Polder potential of an atom with the grating. In particular, we find that strong anisotropy can lead to a repulsive Casimir-Polder potential in the normal direction.

Unifying Microscopic and Continuum Treatments of van der Waals and Casimir Interactions

“…We have consistently found larger deviations in approximate interactions for long, semimetallic molecules such as carbyne wires, whereas compact, insulating molecules such as many proteins are reasonably well described as effectively dilute dielectric particles, allowing these low-order approximations to be more valid. In the future, one might consider more complex macroscopic bodies, such as periodic gratings [17,18] that may elicit larger differences between RMB and approximate interactions even for compact biomolecules, as well as extend these results to incorporate the effects of infrared molecular resonances [16]. …”

“…Simultaneously, recent theoretical and experimental work has characterized dipolar Casimir-Polder (CP) interactions between macroscopic metallic or dielectric objects and atoms, molecules, or Bose-Einstein condensates, further extending to nonzero temperatures, dynamical situations, and fluctuations in excited states (as in so-called Rydberg atoms) [16][17][18][19][20][21][22][23][24][25]. Yet, while theoretical treatments have thus far accounted for the full electrodynamic response of macroscopic bodies (including retardation), they often treat molecules as point dipoles of some effective bulk permittivities or as collections of noninteracting atomic dipoles, ignoring finite size and other many-body electromagnetic effects.In this Letter, motivated by the aforementioned theoretical developments [1,[16][17][18][24][25][26][27][28], we describe an approach that seamlessly connects atomistic descriptions of large molecules to continuum descriptions of arbitrary macroscopic bodies, characterizing their mutual vdW interactions. In particular, while molecules in proximity with macroscopic objects require atomistic descriptions of the latter, and large molecules far from macroscopic objects require consideration of contributions from vibrational (in addition to electronic) resonances to the vdW interaction energy, we focus on a mesoscopic regime involving molecular sizes and separations on the order of 1-100 nm, where macroscopic objects can be treated continuously for the purposes of computing electromagnetic field responses (and molecular vibrational resonances can be neglected), yet electromagnetic retardation in conjunction with the finite sizes, nontrivial shapes, and nonlocal electronic correlations of large molecules need to be self-consistently considered to accurately characterize vdW interactions.…”

The Casimir force for 2d sinusoidal gratings

“…General analytic properties of Rayleigh coefficients were found in Ref. [11]. Existence of repulsive Casimir-Polder potential for an anisotropic atom in the presence of 20 nm thin 1d Au grating was shown in Ref.…”

“…Existence of repulsive Casimir-Polder potential for an anisotropic atom in the presence of 20 nm thin 1d Au grating was shown in Ref. [11].…”

Inducing and controlling rotation on small objects using photonic topological materials

“…Note that this reflection coefficient is not real even when evaluated at imaginary frequencies ω = iξ due to the terms proportional to ε yz . But since this term also flips sign under k → −k the Schwarz reflection principle G (1) (r, r , iξ ) = G (1) (r, r , iξ ) is obeyed which according to [32] implies r pp (k , iξ ) = r pp (−k , iξ ).…”