Potsdam University Potsdam Quantum Optics Group

Universität Potsdam
Institut für Physik
Karl-Liebknecht-Str. 24/25
14476 Potsdam-Golm
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 Publications
 2012
   haakh11b
 
H. R. Haakh, J. Schiefele, and C. Henkel
Feynman Diagrams for Dispersion Interactions Out of Equilibrium -Two-Body Potentials for Atoms with Initial Excitation
Int. J. Mod. Phys. Conf. Ser. 14 (2012) 347-56, proceedings of conference "Quantum Field Theory under the influence of External boundary conditions" (Benasque, Sep 2011).

Abstract

    Diagrammatic techniques are well-known in the calculation of dispersion interactions between atoms or molecules. The multipolar coupling scheme combined with Feynman ordered diagrams significantly reduces the number of graphs compared to elementary stationary perturbation theory. We review calculations of van der Waals-Casimir-Polder forces, focusing on two atoms or molecules one of which is excited. In this case, calculations of the corresponding force are notorious for mathematical issues connected to the spontaneous decay of the excitation. Treating such unstable states in a full non-equilibrium theory provides a physical interpretation of apparent contradictions in previous results and underlines the importance of decay processes for the intermolecular potential. This may have important implications on reactions in biological systems, where excited states may be relatively long-lived and the resonant intermolecular force may result in directed Brownian motion.

[ 1111.3748 ] [ DOI ]

file generated: 3 Mar 2014


   
   
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