Quantum State Transfer among Three Ring-Connected Atoms

A robust quantum state transfer scheme is discussed for three atoms that are trapped by separated cavities linked via optical fibers in a ring connection. It is shown that, under the effective three-atom Ising model, an arbitrary unknown quantum state can be transferred from one atom to another deterministically via an auxiliary atom with maximum unit fidelity. The only required operation for this scheme is replicating turning on/off the local laser fields applied to the atoms for two steps with time cost √2π/Γ₀. The scheme is insensitive to cavity leakage and atomic position due to the condition Δ≈κ·g. Another advantage of this scheme is that the cooperative influence of spontaneous emission and operating time error can reduce the time cost for maximum fidelity and thus can speed up the implementation of quantum state transfer.