Heidelberg 2015 – scientific programme

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Q: Fachverband Quantenoptik und Photonik

Q 68: Matter Wave Optics I

Q 68.2: Talk

Friday, March 27, 2015, 11:30–11:45, K/HS2

Rotationally averaged Casimir-Polder forces — •Johannes Fiedler and Stefan Scheel — Institute of Physics, University of Rostock, D-18055 Rostock, Germany

Casimir-Polder forces between a microscopic particle and a macroscopic surface arise from the ground-state fluctuations of the quantized electromagnetic field. Commonly, the theoretical description of this interaction assumes the electric-dipole approximation in which the particle is represented by a point dipole [1]. However, recent interference experiments use large organic molecules at relatively high velocities which interfere on very thin material gratings [2]. A consequence of this set of parameters is that the molecules approach the grating surface very closely, at typical distances in the range of only a few nanometers, which implies that the molecules cannot be treated as point dipoles any longer. In order to cover the experimental situtation, we have developed a theory describing the interaction of large (i.e. spatially extended) molecules very close to surfaces. We employ the idea of Gaussian polarisability densities to include the size and shape of the molecule while retaining the dipole approximation [3]. We will investigate the effect of molecular rotation on the Casimir-Polder interaction during transit through the grating.

[1] S.Y. Buhmann, Dispersion Forces I (Springer, Heidelberg, 2012).

[2] T. Juffmann et al. Nature Nano 7, 297 (2012).

[3] D.F. Parsons and B.W. Ninham, J. Phys. Chem. A 113, 1141 (2009).