[Review paper]
New Routes to Studying the Dressed Photon
Motoichi Ohtsu
keywords: dressed photon, phonon, silicon, laser, off-shell
Abstract
First, this paper reviews the history of studies on the dressed photon (DP) by classifying them into older and modern times, between which there exists a great difference in the concepts, principles, and methods involved. Quantum field theories, developed more recently, have succeeded in solving three problems originating from the intrinsic features of the light–matter interactions occurring in nanometric spaces. First, a variety of applications of these theoretical studies, which have resulted in the development of generic technology, are introduced. Second, the present status of experimental studies is reviewed. Among them, the fabrication and operation of novel light emitting devices using crystalline silicon (Si) are demonstrated. In these devices, the DP enabled high-power light emission even though Si is an indirect-transition-type semiconductor. Furthermore, it is shown that these devices exhibit a unique feature, named photon breeding. Third, a future outlook of DP research is presented, where it is pointed out that novel theoretical studies are required in order to support the rapid progress made in recent experimental studies and to develop further novel application technologies. As a route to such novel theoretical studies, three steps are presented, and several results derived from these steps are reviewed. Furthermore, a theory of micro–macro duality in the quantum field is presented as a powerful tool that will enable future progress in theoretical studies. Finally, a variety of phenomena in nano-systems, macro-systems, inorganic materials, and organic materials, which have similar features to those of the DP, are introduced. By referring to this similarity, it is pointed out that studies on the DP are connected to a more generic and broader science that is expected to produce a novel generic science, named off-shell science, in the near future.