Talk given by

Dr. Stefan Buhmann

FRIAS, Universität Freiburg

Freiburg, Germany

Abstract: The quantum vacuum is one of the most counter-intuitive concepts of quantum electrodynamics. Whereas the classical vacuum refers to a region of space that is devoid of any particles or fields, its quantum counterpart contains fluctuating electromagnetic fields even in the most idealised case. The structure of these virtual photons can be significantly altered by the presence of magnetodielectric bodies or media. I will explain how a realistic notion of the quantum vacuum in the presence of such bodies can be given within the theory of macroscopic quantum electrodynamics [1].

The signature of the quantum vacuum is manifest in the interaction of virtual photons with charged matter. As noted by Casimir in 1948, they give rise to the famous Casimir force between two perfectly conducting plates [2]. I will give an overview over the Casimir effect and its significance in nanotechnology, including the possibility to realise a Casimir-based glue [3] or to tune Casimir forces between topological insulators via applied magnetic fields [4].

A second prominent vacuum effect is the spontaneous decay of excited atoms or molecules. As shown by Purcell, it is also sensitive to the presence of magnetodielectric environments [5]. We have recently considered interatomic Coulomb decay as a process where a highly excited ion transmits its energy to a nearby neutral atom ionising the latter [6]. Using macroscopic quantum electrodynamics, we show how this process can be enhanced by retardation, intervening media such as water and interfaces.

[1] S. Scheel and S. Y. Buhmann, Acta Phys. Slowaka 58 (5), 675 (2008); Dispersion Forces I - Macroscopic Quantum Electrodynamics and Ground-State Casimir, Casimir–Polder and van der Waals Forces, S. Y. Buhmann (Springer, Heidelberg, 2013).
[2] H. B. G. Casimir, Proc. K. Ned. Akad. Wet. 51, 793 (1948).
[3] J. Katt, P. Barcellona, R. Bennett, O. S. Bokareva, H. Feth, A. Rasch, P. Reith and S. Y. Buhmann, Langmuir 33 (21), 5298 (2017).
[4] S. Fuchs, F. Lindel, M. Antezza, G. Hanson, R. Krems and S. Y. Buhmann, submitted to Phys Rev. A (2017).
[5] E. M. Purcell, Phys. Rev. 69, 674 (1946).
[6] L. S. Cederbaum, J. Zobeley, F. Tarantelli, Phys. Rev. Lett. 79 (24), 4478 (1997).