Coherent Control of an Atomic Collision in a Cavity

Abstract

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 process, mediated by the virtual emission and absorption of a microwave photon, is characterized by a collision mixing angle 4 orders of magnitude larger than for atoms colliding in free space with the same impact parameter. The final entangled state is controlled by adjusting the atom-cavity detuning. This procedure, essentially insensitive to thermal fields and to photon decay, opens promising perspectives for complex entanglement manipulations.

Exciton-plasmon coupling interactions: from principle to applications

“…h〉 Put the two atoms into the cavity at the same time, and let the atoms interact with the cavity after time t leaves the cavity. Then, the interaction between two atoms and the cavity field need to be described, and the evolution of the system state can be written as [124] (A) Schematic of the conversion of phonochromic between spiropyran (SPI) [44] and merocyanine (MC) in an optical cavity [111]. (B) Spectrum of transmission of the coupled system in the cavity.…”

Quantum entanglement and disentanglement of multi-atom systems

“…Finally it may be mentioned, that threshold behavior of entanglement is also possible in this system, as indicated by the presence of the term 2 √ ρ 11 ρ 44 in Eq. (39). Thus, similar to the above example, a threshold of entanglement could be observed only if the redistribution of the population involves both of the separable states.…”

“…Secondly, a close look at Eq. (39) reveals that the correlations between the entangled states have a further destructive rather than constructive effect on entanglement. This is in contrast to the correlations between product states that always appear as constructive correlations for entanglement.…”

“…(39) that an initial entanglement encoded in a spin anti-correlared state, the symmetric or antisymmetric states, would decay asymptotically in time without any discontinuity. Expression (39) clearly shows that necessary condition for entanglement sudden death is a simultaneous population of the ground |Ψ 1 and the two-photon |Ψ 4 states.…”

“…The suppression arises from a reduction of the number of field modes to which atoms can be coupled. With the help of a cavity, entanglement of atomic systems can be tested by probing the atomic states of the atoms leaving the cavity, or by a measurement of the cavity photons [24,39]. For example, the absence of fluorescence can be a signature for maximally entangled atom pairs which, in principle, can be used to create cluster states for one-way quantum computing [40].…”