Development of Single Photon Experiments Using Type-I and Type-II Spontaneous Parametric Downconversion

Andrew Laugharn, S. Maleki

Stephen DiIorio

Preston Alexander, Jackson McDonld, J. P. Harrington +1 more

Shigeki Takeuchi

Beamlike twin-photon generation by use of type II spontaneous parametric downconversion is demonstrated. The intensity distribution of each beam is round, and the emission angle is very small (0.9 degrees ). As a result, a high coincidence-count rate per unit of pump power was recorded. The ratio of coincidence-count rate to single-count rate was estimated to be 80% in this experiment. These features suggest that this method is useful for generation of a single-photon state and is applicable to bright, entangled twin-photon sources.

Alexander V. Sergienko, Thomas E. Kiess, Y. H. Shih +2 more

Polarization correlation measurement of two-photon state generated in type-II spontaneous parametric downconversion (SPDC) has been performed in a single input port beam splitter configuration. Two orthogonally polarized entangled photons with degenerate k vectors were directed to the single input port 50%-50% beam splitter. Polarization were measured with linear and circular polarization entangled state by the use of two polarization analyzers followed by two photon counting detectors. A strong correlation of polarization has been observed. The type of two-photon state generated in Type-II SPDC was tested. A strong dependence of the polarization correlation upon the spectral bandwidth of the detector spectral filter was found and a different correlation between linear and circular polarization entangled state were observed. It seems that the standard theoretical models for SPDC need to be improved in order to provide a comprehensive treatment for the result of the experiment.

Preston Alexander, Scott Baldwin, S. Blane McCracken +1 more