We do research on quantum systems of various kinds that interact with their classical environment. A good example are atoms whose energy levels shift when they are next a reflecting wall or inside a cavity. Such effects can often be understood in various ways, but we try to use the techniques of quantum field theory because these are extremely powerful, efficient, and versatile. This does involve some concepts that are classically difficult if not impossible to grasp, as for example the quantum vacuum which is teeming with virtual excitations that can become real when the vacuum state is forced to change e.g. due to moving boundaries.
Many effects due to quantum systems interacting with classical boundaries are extremely small, but some are not and have in fact facilitated a whole range of new devices, like e.g. laser diodes which are found in every CD or DVD player. With the advance of nanotechnology many more such devices may become practically possible. Our research is contributing with new ideas on the sorts of effects that may be exploitable in nanotechnological applications in the future.