Qutrit state engineering with biphotons

Abstract

The realization of arbitrary qutrit states that exploits the polarization state of single-mode biphoton field was analyzed. The single-mode biphoton field consists of pairs of correlated photons, easily obtained with the help of spontaneous parametric down-conversion. The twin photons forming a biphoton have equal frequencies and propagate along the same direction. The advantage of this method is that all control of the amplitude and phases of each polarization state in superposition was done using linear optical elements, making it easy to switch from one state to another and providing the full control over the polarization state.