As part of the condensed matter theory, our activity covers a class of systems called strongly correlated material systems. Our main research interest is on the low dimensional semiconductors and related lattice models such as Hubbard models with strong interactions. One of the characteristics of our themes is to focus not only on the ground state but also the excited ones. This enables us to clarify the dynamical properties of the system, e.g. optical properties, which is influenced by the strong correlation effects. Such kind of topic has two faces: one is the fundamental aspect to clarify how the matter is formed. For example, in electron-hole systems the elementary particle that play a main role consists of plus and minus charges, and the knowledge on how the excitons are bounded out of these charges and how they behave gives us an understanding on the very basics of the phase of matter. The connectivity to the application is also available, as the knowledge of the dynamical properties in a simple correlated models enable the efficient design of optical devices or solar batteries. We also target the open systems where there are interactions between the target systems and the circumstances, e.g. phonons, photons, or measurement devices, where the effect of manybody interactions on dynamics is a highly nontrivial issue to be disclosed.
Phase diagram of one-dimensional electron-hole system.
Binding energies of trions and biexcitons
in semiconducting carbon nanotubes.