  We report on the experimental demonstration of a source of hybrid
entanglement pairs between two different degrees of freedom, a 1550 nm time-bin
qubit and an 810 nm polarization qubit. The polarization qubit at 810 nm is
transformed by an asymmetric Mach-Zehnder interferometer consisted of a Glan
laser prism and a polarization-maintaining fiber. We obtained visibilities of
95.8% and 88% along Z-Z and X-X axes on the Poincare sphere, respectively with
a coincidence count rate of more than 800 c/s after entanglement format
transformation. These values are well above the threshold of 70.7% needed to
violate a Bell inequality and allow distilling a secure key in the quantum key
distribution.
