We propose a scheme for the generation of two collections of atoms trapped in distant cavities connected by an optical fiber. The virtual photon exchange leads to the entanglement between these two atomic ensembles. During the operation the atomic system, cavity modes, and fiber are not excited, which is important in view of decoherence.
A scheme is proposed for the deterministic generation of three-dimensional entanglement of two distant atoms separately trapped in two optical cavities connected by an optical fiber. Employing adiabatic passage along dark states, the atoms are always in ground states, in particular, the fiber mode remains in the vacuum state due to the quantum destructive interference, and the population of the cavities being excited can be negligible under certain conditions. In this sense, our scheme constructs an effective way to avoid the atomic spontaneous emission and the decays of fiber and cavities.
We propose a scheme for generating maximally entangled states for three atoms trapped in three distant cavities connected by two identical single-mode fibers. During the operation, neither the atomic system nor the fibers are excited, which is important in view of decoherence. Under certain conditions, the probability of the excited cavities can be negligible. Taking advantage of adiabatic passage, the GHZ state can be generated deterministically, and the fidelity of entanglement is insensitive to fluctuation of experimental parameters. Compared to the previous schemes, the significant advantage of the proposed scheme is that each cavity can interact with the other two directly, which can avoid the effect of indirect interaction brought about using only local quantum operator and nonlocal resources.
We propose an efficient scheme for the generation of two-mode squeezed states for two separated atomic ensembles trapped in distant cavities. The scheme is based on selective couplings between the collective atomic modes and two linearly transformed common field modes mediated by an optical fiber or a third cavity. The quanta of the transformed atomic modes are exhausted due to the linear coupling with the transformed field modes, bringing the original atomic modes into the two-mode squeezed states. The experimental implementation of the scheme would be an important step toward quantum communication and networking with continuous variables.
We propose a scheme for the generation of entangled coherent states for two separate cavities connected by an optical fiber. In the scheme, an atom is trapped in the first cavity and driven by a strong classical field. Under the condition that the cavity-fiber coupling is much larger than the atom-cavity coupling, the two cavity modes evolve from a vacuum state to entangled coherent states correlated with the atomic states. During the evolution, the fiber mode is not excited and the fiber loss does not affect the fidelity of the produced state.
We propose a scheme for the generation of entangled states for multiple atoms trapped in three distant cavities connected by two identical single-mode fibers. Compared with the previous schemes, the distinct advantages of the proposed scheme are: First, all the cavities in the proposed protocol can interact with each other freely, which is important in quantum communication and distributed quantum computation. Secondly, in the scheme, the atoms, cavities, and fiber mode are in resonance. Thus, the required interaction time is short, which is important in view of decoherence. In principle, the proposed scheme can be extended to generate n atoms entangled states.