Detecting photons transporting qubits without destroying quantum information

Even though quantum communication is tap-proof, it is so far not particularly efficient. Researchers at the Max Planck Institute of Quantum Optics want to change this. They have developed a detection method that can be used to track quantum transmissions. Quantum information is sent over long distances in the form of photons (i.e. light particles). However, these are quickly lost. Finding out after only a partial distance whether such a photon is still on its way to its destination or has already been lost, can significantly reduce the effort required for information processing. This would make applications such as the encryption of money transfers much more practicable.