Optical trap for two-dimensional excitons*

For its potential optical controllability as quantum degrees of freedom, the exciton in two-dimensional system has attracted much attentions. In this presentation, we propose an optical trapping technique for the exciton. Exploiting the energy shift mechanism of excitonic system coupled to the electromagnetic field, spatial confinement potential can be implemented. The dimensionality and symmetry of the potential can be dynamically tunable. We performed an ab initio calculation of the excitonic states in graphane, a two-dimensional wide gap semiconductor with D_3d symmetry, based on GW+BSE method by using BerkeleyGW package. The lowest excitonic state belongs to E_u representation, followed by E_g and A_2g excitons of which energy levels are 500meV and 650meV apart from E_u exciton, respectively. Two- and three-level systems can be implemented by coupling these levels with optical fields. We will report the possible depth and polarization dependency of the potential by applying nearly infrared laser light.