Quantum Teleportation, Swapping Proved

The teleportation and swapping of quantum states has been predicted in theory and presumed to be true in reality. Now researchers at Universität Wien in Vienna, Austria, have confirmed the phenomena experimentally.

In the Jan. 7 issue of Physical Review Letters, they described how they employed two-pass down-conversion of 394-nm radiation in BBO to generate two entangled pairs of photons for Bell-state and polarization analysis. The setup displayed a Bell parameter of 2.421 ±0.091 for the Clauser-Horne-Shimony-Holt inequality, violating the classical limit by 4.6 standard deviations, and enabled them to perform a delayed-choice experiment -- projecting the pairs into entanglement by subjecting them to different measurements after their polarizations had been recorded.