Physicists around the world are searching for the best way to realize a quantum computer. Now scientists of the team around Stefan Kuhr and Immanuel Bloch at the Max Planck Institute of Quantum Optics (Garching/Munich) took a decisive step in this direction. They could address and change the spin of single atoms with laser light and arrange them in arbitrary patterns. In this way, the physicists strung the atoms along a line and could directly observe their tunnelling dynamics in a "racing duel" of the atoms. A register of hundreds of addressable quantum particles could serve for storing and processing of quantum information in a quantum computer.
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The new addressing technique allows many interesting studies of the dynamics of collective quantum states, as they appear in solid state systems. It also opens new perspectives in quantum information processing. ''A Mott isolator with exactly one atom per lattice site acts as a natural quantum register with a few hundred quantum bits, the ideal starting point for scalable quantum information processing'' as Stefan Kuhr explains. ''We have shown that we can individually address single atoms. In order for the atom to suit as a quantum bit, we need to generate coherent superpositions of its two spin states. A further step is to realize elementary logical operations between two selected atoms in the lattice, so-called quantum gates.''

The research was published [http://dx.doi.org/10.1038/nature09827 the recent issue of Nature] ([http://arxiv.org/abs/1101.2076 arXiv:1101.2076]) See also http://www.quantum-munich.de/media/single-spin-addressing-in-an-atomic-m... for more details.