Quantum Institute: Visitor Schedule

The Quantum Lunch is regularly held on Thursdays in the Theoretical Division Conference Room, TA-3, Building 123, Room 121.
For more information, contact Diego Dalvit.
To add your name to the Quantum Lunch email list, contact Charlotte Carter

Thursday, April 2, 2009
12:30 PM - 2:00 PM

Speaker: Stefan Buhmann, Imperial College, London

Technical Host: Diego Dalvit

TOPIC: Macroscopic quantum electrodynamics and dispersion forces

Abstract
Magnetoelectric matter and the quantum electromagnetic field can strongly influence each other: Macroscopic bodies determine the structure of the electromagnetic field, while the electromagnetic field in turn acts on bodies or individual atoms to induce forces. Starting with the first aspect of this interdependence, I will present macroscopic quantum electrodynamics in linear, causal media as a general theory of the quantum electromagnetic field in the presence of magnetoelectrics. The noise polarisation and magnetisation unavoidably present in inside absorbing bodies act as sources of the electromagnetic field. Its propagation is governed by the classical Green tensor as determined by bodies' electric permittivity and magnetic permeability. In the second part of the talk, I will discuss the impact of the electromagnetic field on matter. Even in its vacuum state, the quantum electromagnetic field does not vanish completely, but exhibits fluctuations. When a polarisable object such as an atom or a magnetoelectric body interacts with this fluctuating field, it experiences a force. I will present a general theory of these dispersion forces, concentrating on Casimir-Polder forces between atoms and bodies as well as van der Waals forces between atoms. Specific aspects to be discussed include duality invariance, the relation between different dispersion forces, the local-field corrections present for atoms embedded in a medium, the influence of thermal fields, and the possible impact of a metamaterial perfect lens.