Building the Quantum Internet

(PHOTO: An artist's depiction of the two-quantum bit created by researchers/Science,AAAS)(HN, 4/2/2012) - Communications networks are vital for day-to-day lives, & now the 1st prototype of a quantum one has been developed based on interfaces between single atoms & photons. For a quantum network to be useful, the exchange of quantum information must be reversible; difficult, because quantum information is very fragile, & the no-cloning theorem prevents the copying of a different quantum state. A breakthrough in solving this problem has been achieved by a group led by professor Gerhard Rempe of the Max Planck Institute of Quantum Optics in Germany, using individual atoms to store information & transfer data by the controlled exchange of photons; the 1st elementary quantum network for secure communications.

(PHOTO: Single atoms form the nodes of an elementary quantum network in which quantum information is transmitted by the controlled exchange of single photons/Andreas Neuzner, MPQ)What it means? Information can be transmitted, bit by bit, from 1 atom to a 2nd atom by mapping its quantum state onto individual photons. The photons travel through a fiber optic cable & are absorbed by the 2nd atom which can then send information back to the 1st atom, or act as a hub to any number of networked atoms - proving that the quantum states can be transferred much better than is currently possible with any classical network. The group also demonstrated `entanglement', or a correlated state, between 2 physically separated network nodes which researchers believe could serve as a model for the teleportation of quantum information over very large distances, & might enable an entire quantum internet. (Read more at CNET)