Qubits Teleported over 2 km of Fiber

A team of researchers at the University of Geneva has teleported quantum states carried on 1.3-µm photons onto 1.55-µm photons over 2 km of standard dispersion-shifted optical fiber. The experiment, which was described in the Jan. 30 issue of Nature, opens the door to the development of quantum relays that would extend the range of quantum cryptography systems by an order of magnitude.

The scientists used a variable coupler to encode the qubits to be teleported in the superposition of time bins, which makes them less susceptible to decoherence than those encoded in polarization. The setup displayed a mean fidelity of more than 80 percent for the two classes of quantum states used in the experiments.