Entanglement Concentration of Entangled Squeezed Vacuum States

By analysing the action of a beamsplitter on squeezed vacuum states (SVSs), it is found that, if the two input light beams of the beamsplitter have the same squeezing amplitude and phase, the output state is a two-mode SVS. If the two input light beams of the beam splitter have the same squeezing amplitude but a phase difference of π, the output state is a direct product state of two single-mode SVSs. Based on these results, we propose to distill maximally entangled SVS from partially entangled SVS via using 50/50 beam splitter and photodetectors.