Production of Ba Metastable State via Superradiance

We describe in this paper a fast and efficient method of producing a high density of barium (Ba) atoms in the 1D2 metastable state, which is a candidate initial state for a new class of cooperative and coherent optical process called paired superradiance (PSR). In the experiment, Ba atoms are excited first by laser light to the 1P1 state and then brought to the desired state 1D2 via radiative transition in the superradiance (SR) mode. It is found that a production efficiency (from 1S0 to 1D2) of more than ∼30% is achieved within a time interval of a few nanoseconds for a Ba density n > 1019 m−3. Several key features of SR important for future PSR experiments are also studied.