A quantum teleportation experiment at Universität Wien in Vienna, Austria, has confirmed the feasibility of procedures that involve freely propagating qubits and quantum repeaters. The results of the study appear in the Feb. 13 issue of Nature.

The researchers inserted a series of neutral-density filters into one of the modes of the apparatus to increase attenuation and thereby reduce the probability of unwanted coincidences in other modes. Previous setups demanded the sacrifice of some photons to confirm that teleportation had occurred.

The new technique displayed a fidelity of 0.85 ±0.02, which is better than is theoretically required to implement quantum repeater schemes suitable for long-distance applications.