Researchers from the Physikalisches Insitut of the University of Stuttgart for the first time systematically created entangled quantum states in diamond. As these results were obtained under ambient conditions they make diamond an ideal candidate for building a quantum computer working at room temperature. This seems to be impossible for other materials. The work is published in the prestigious magazine Science appearing on 6 June 2008.)
Physicists describe the world of atoms by quantum mechanics. One of its strangest characteristics allows one to link two objects without any noticeable interaction even over long distances. No wonder Einstein called this a spooky interaction. Nowadays entanglement is proven to exist without doubt. One of the most spectacular experiments based on this unusual characteristic is quantum teleportation where the properties of one quantum object are transferred to another one at a remote location.
Nevertheless this effect is very sensitive to any perturbations. Thus physicists in most of the cases have to work under extreme conditions like temperatures close to the absolute Zero point to entangle quantum objects. This is not necessary in diamond, as has been shown by scientist from Stuttgart. In their experiments they shot Nitrogen atoms into the diamond lattice at high speed. These impurities are detectable by their fluorescence and they change the diamond color to pink. Because of its unmatched stiffness the diamond lattice is shielding the Nitrogen atoms and thus allows detecting quantum effects such as entanglement under ambient conditions.
This gave the researchers from Stuttgart the opportunity to create suitable quantum states among the building blocks of the diamond lattice, namely the Carbon atoms. One percent of those Carbon atoms possess a magnetic moment what allows them to interact with an implanted Nitrogen atom in close vicinity. This interaction was used to individually address the Carbon atoms which have been entangled in the end. This is one of the major milestones on the way towards a quantum computer, a technology supposed to build ultrafast computers.