Casimir-Polder interaction between an atom and a dielectric slab (original) (raw)
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Dynamical Casimir-Polder interaction between an atom and surface plasmons
Physical Review A, 2014
We investigate the time-dependent Casimir-Polder potential of a polarizable two-level atom placed near a surface of arbitrary material, after a sudden change in the parameters of the system. Different initial conditions are taken into account. For an initially bare ground-state atom, the time-dependent Casimir-Polder energy reveals how the atom is "being dressed" by virtual, matter-assisted photons. We also study the transient behavior of the Casimir-Polder interaction between the atom and the surface starting from a partially dressed state, after an externally induced change in the atomic level structure or transition dipoles. The Heisenberg equations are solved through an iterative technique for both atomic and field operators in the medium-assisted electromagnetic field quantization scheme. We analyze in particular how the time evolution of the interaction energy depends on the optical properties of the surface, in particular on the dispersion relation of surface plasmon polaritons. The physical significance and the limits of validity of the obtained results are discussed in detail. PACS numbers: 34.35.+a -interactions of atoms with surfaces; 42.50.Nn -quantum optical phenomena in conducting media; 73.20.Mf -surface plasmons
Journal of Physics A: Mathematical and General, 2006
The Casimir-Polder and van der Waals interactions between an atom and a flat cavity wall are investigated under the influence of real conditions including the dynamic polarizability of the atom, actual conductivity of the wall material and nonzero temperature of the wall. The cases of different atoms near metal and dielectric walls are considered. It is shown that to obtain accurate results for the atomwall interaction at short separations, one should use the complete tabulated optical data for the complex refractive index of the wall material and the accurate dynamic polarizability of an atom. At relatively large separations in the case of a metal wall, one may use the plasma model dielectric function to describe the dielectric properties of wall material. The obtained results are important for the theoretical interpretation of experiments on quantum reflection and Bose-Einstein condensation.
Casimir Effects in Atomic, Molecular, and Optical Physics
Advances in Atomic, Molecular and Optical Physics, 2010
The long-range interaction between two atoms and the long-range interaction between an ion and an electron are compared at small and large intersystem separations. The vacuum dressed atom formalism is applied and found to provide a framework for interpretation of the similarities between the two cases. The van der Waals forces or Casimir-Polder potentials are used to obtain insight into relativistic and higher multipolar terms.
Casimir-Polder interaction between an atom and a cavity wall under the influence of real conditions
Physical Review A - Atomic, Molecular, and Optical Physics, 2004
The Casimir-Polder interaction between an atom and a metal wall is investigated under the influence of real conditions including the dynamic polarizability of the atom, finite conductivity of the wall metal, and nonzero temperature of the system. Both analytical and numerical results for the free energy and force are obtained over a wide range of atom-wall distances. Numerical computations are performed for an Au wall and metastable He * , Na, and Cs atoms. For the He * atom we demonstrate, as an illustration, that at short separations of about the Au plasma wavelength at room temperature the free energy deviates up to 35% and the force up to 57% from the classical Casimir-Polder result. Accordingly, such large deviations should be taken into account in precision experiments on atom-wall interactions. The combined account of different corrections to the Casimir-Polder interaction leads to the conclusion that at short separations the corrections due to the dynamic polarizability of an atom play a more important role than-and suppress-the corrections due to the nonideality of the metal wall. By comparison of the exact atomic polarizabilities with those in the framework of the single oscillator model, it is shown that the obtained asymptotic expressions enable calculation of the free energy and force for the atom-wall interaction under real conditions with a precision of 1%.
Optomechanical Rydberg-Atom Excitation via Dynamic Casimir-Polder Coupling
Physical Review Letters, 2014
We study the optomechanical coupling of a oscillating effective mirror with a Rydberg atomic gas, mediated by the dynamical atom-mirror Casimir-Polder force. This coupling may produce a near-field resonant atomic excitation whose probability scales as ∝ (d 2 a n 4 t) 2 /z 8 0 , where z0 is the average atom-surface distance, d the atomic dipole moment, a the mirror's effective oscillation amplitude, n the initial principal quantum number, and t the time. We propose an experimental configuration to realize this system with a cold atom gas trapped at a distance ∼ 2 · 10 µm from a semiconductor substrate, whose dielectric constant is periodically driven by an external laser pulse, hence realizing en effective mechanical mirror motion due to the periodic change of the substrate from transparent to reflecting. For a parabolic gas shape, this effect is predicted to excite about ∼ 10 2 atoms of a dilute gas of 10 3 trapped Rydberg atoms with n = 75 after about 0.5 µs, hence high enough to be detected in typical Rydberg gas experimental conditions. PACS numbers: 12.20.Ds,42.50.Ct
Anisotropic atom-surface interactions in the Casimir-Polder regime
Physical Review A, 2014
The distance-dependence of the anisotropic atom-wall interaction is studied. The central result is the 1/z 6 quadrupolar anisotropy decay in the retarded Casimir-Polder regime. Analysis of the transition region between non-retarded van der Waals regime (in 1/z 3 ) and Casimir-Polder regime shows that the anisotropy cross-over occurs at very short distances from the surface, on the order of 0.03λ, where λ is the atom characteristic wavelength. Possible experimental verifications of this distance dependence are discussed. PACS numbers: 34.35.+a, 03.75.Be, 12.20.Fv The force between neutral polarisable systems is a ubiquitous phenomenon in nature, with many applications in physics, chemistry, biology. . . A paramount example is the long-range interaction potential between neutral microscopic quantum systems, like atomic systems, and a solid surface. For plane surfaces this interaction is usually governed by a power-law attractive potential . For atom-surfaces distances z smaller than the wavelengths of the optical transitions involved in the atomic polarisability, the interaction is of the dipoleinduced dipole type, and governed by the well-known non-retarded van der Waals potential in −C 3 /z 3 , which reflects the correlations of dipole fluctuations [1]. At larger distances, retardation effects get important, and asymptotically lead to a −C 4 /z 4 potential, as demonstrated in the pioneering work of Casimir and Polder [2].
Casimir Forces in Nanostructures
physica status solidi (b), 2002
We present a theoretical calculation of Casimir forces in structures made of parallel slabs that can be made of dispersive and absorptive materials. The materials are characterized by the reflectivity amplitude coefficients of the vacuum modes between the slabs. In particular, we present results for an antisymmetric configuration in which one plate is a metal and the other one a dielectric material. As a reference, we also calculate the force for the symmetric case (two metallic or two dielectric slabs). Our results show that the Casimir force could have a relevant contribution to the interaction between the tip and sample in atomic force microscopy experiments.
Casimir interaction between a dielectric nanosphere and a metallic plane
Physical Review A, 2011
We study the Casimir interaction between a dielectric nanosphere and a metallic plane, using the multiple scattering theory. Exact results are obtained with the dielectric described by a Sellmeier model and the metal by a Drude model. Asymptotic forms are discussed for small spheres, large or small distances. The well-known Casimir-Polder formula is recovered at the limit of vanishingly small spheres, while an expression better behaved at small distances is found for any finite value of the radius. The exact results are of particular interest for the study of quantum states of nanospheres in the vicinity of surfaces.
Intermediate-Range Casimir-Polder Interaction Probed by High-Order Slow Atom Diffraction
Physical Review Letters, 2021
At nanometer separation, the dominant interaction between an atom and a material surface is the fluctuation-induced Casimir-Polder potential. We demonstrate that slow atoms crossing a silicon nitride transmission nanograting are a remarkably sensitive probe for that potential. A 15% difference between nonretarded (van der Waals) and retarded Casimir-Polder potentials is discernible at distances smaller than 51 nm. We discuss the relative influence of various theoretical and experimental parameters on the potential in detail. Our work paves the way to high-precision measurement of the Casimir-Polder potential as a prerequisite for understanding fundamental physics and its relevance to applications in quantum-enhanced sensing.
Harmonic oscillator model for the atom-surface Casimir-Polder interaction energy
Physical Review A, 2012
In this paper we consider a quantum harmonic oscillator interacting with the electromagnetic radiation field in the presence of a boundary condition preserving the continuous spectrum of the field, such as an infinite perfectly conducting plate. Using an appropriate Bogoliubov-type transformation we can diagonalize exactly the Hamiltonian of our system in the continuum limit and obtain non-perturbative expressions for its ground-state energy. From the expressions found, the atom-wall Casimir-Polder interaction energy can be obtained, and well-know lowest-order results are recovered as a limiting case. Use and advantage of this method for dealing with other systems where perturbation theory cannot be used is also discussed.