Nature Phys. doi:10.1038/nphys1183 (2009) and Nature Phys. doi:10.1038/nphys1178 (2009)

The groups of Antoine Browaeys of the University of Paris-South in Palaiseau and Mark Saffman of the University of Wisconsin, Madison, have independently demonstrated a simple set-up that could form the basis of a quantum logic gate, a system that has the advantage of having components widely separated enough to be easily addressable one at a time.

Their Rydberg blockades hold rubidium atoms in optical traps several micrometres apart. Lasers are used to excite an electron in one atom to an extent that blocks its neighbour from achieving a similar excited state. The next step will be to demonstrate useful entanglement by creating a working logic gate with the blockade.