Understanding electromagnetic fluctuations in microstructured geometries

Alejandro Rodriguez, Harvard University

The quantum and thermal fluctuations of charges making up neutral matter give rise to a number of exciting and interesting electromagnetic phenomena. For example, the electromagnetic fields induced by fluctuating charges inside two macroscopic bodies exert a distance-dependent force between the bodies known as the Casimir force. If the two bodies lie at different temperatures, then in addition to a force, these fluctuations also cause the two bodies to exchange heat in the form of electromagnetic waves. Although the existence of such phenomena has been known for decades, until recently little, if anything, was known about the physics of such interactions in complicated geometries, where the electromagnetic fields are known to be dramatically altered. Although the forces and heat flow between macroscopic bodies separated by everyday length scales is negligible, these effects tend to play a significant role at micro and sub-micron length scales. For example, Casimir forces, which are most often attractive, have been known to lead to the stiction and failure of microelectromechanical systems.

Similarly, the heat transfer problem is at the heart of many naturally occurring processes and nanotechnological systems, such as in new generations of thermophotovoltaic devices. One of the main goals of the field of fluctuation induced interactions (FII) is to understand how and to what extent one can exploit and tailor these effects. In this talk, I will describe a number of the computational tools, based on standard techniques from numerical classical electromagnetism, that my colleagues and I developed for the purpose of studying FII in arbitrary geometries. I discuss a number of interesting predictions of levitation and repulsion induced by Casimir forces in geometries that deviate from the conventional and well-understood parallel plate geometries, as well as our recent prediction of enhanced near-field heat transfer between microstructured films.

Abstract Author(s): Alejandro Rodriguez