building block for transmission of quantum information over long distance with low loss tagged posts

Ion–photon entanglement scheme and quantum-state tomography.

Physicists have succeeded in entangling a single atom with a single photon in the telecom wavelength range. This constitutes a basic building block for transmission of quantum information over long distance with low loss. Communication using quantum states offers ultimate security, because eavesdropping attempts perturb the signal and would therefore not remain undetected. For the same reason, though, long-distance transmission of that information is difficult. In classical telecommunication, the increasing attenuation of the signal is counteracted by measuring, amplifying and re-sending it in so-called repeater stations, but this turns out to be as detrimental to the quantum information as an eavesdropper.

Therefore, a differe...