Coherent control of an atomic collision in a cavity - art. no. 037902

Following a recent proposal by S.B. Zheng and G.C. Guo [Phys. Rev. Lett. 85 , 2392 (2000)], we report an experiment in which two Rydberg atoms crossing a nonresonant cavity are entangled by coherent energy exchange. The proces s, mediated by the virtual emission and absorption of a microwave photon, i s characterized by a collision mixing angle 4 orders of magnitude larger th an for atoms colliding in free space with the same impact parameter. The fi nal entangled state is controlled by adjusting the atom-cavity detuning. Th is procedure, essentially insensitive to thermal fields and to photon decay , opens promising perspectives for complex entanglement manipulations.