Physicists have taken a step toward a quantum Internet constructed from diamond crystals by entangling data stored in diamond pieces three meters apart so that measuring the state of one quantum bit (qubit) instantaneously fixes the state of the other. A quantum Internet would utilize entangled photons transmitted along fiber-optic cables to subsequently entangle qubits, a milestone that could potentially provide ultra-secure communications or deliver software and data to future quantum computers. The researchers entangle qubits in separate diamond pieces using lasers to entangle each qubit with a photon at temperatures of 10 degrees kelvin. The photons converge midway through a fiber-optic cable, where they are themselves entangled. Entanglement is currently accomplished only once in every 10 million tries. A key objective of the method is providing a foundation for quantum repeaters, which would facilitate long-distance quantum communications through entangled chains. Delft University of Technology researcher Ronald Hanson says diamond’s ability to link remote processors in networks is better than that of ion systems. Diamond-stored qubits also can be maintained at room temperature, since diamond’s surrounding carbon lattice protects them from stray magnetic fields or vibrations that might disrupt their superposition.
More info: Nature (04/24/13) Richard Van Noorden