Ground-state blockade of Rydberg atoms and application in entanglement generation. (arXiv:1705.03081v2 [quant-ph] UPDATED)

We propose a mechanism of ground-state blockade between two $N$-type Rydberg
atoms in virtue of Rydberg-antiblockade effect and Raman transition. Inspired
by the quantum Zeno effect, the strong Rydberg antiblockade interaction plays a
role in frequently measuring one ground state of two, leading to a blockade
effect for double occupation of the corresponding quantum state. By encoding
the logic qubits into the ground states, we efficiently avoid the spontaneous
emission of the excited Rydberg state, and maintain the nonlinear
Rydberg-Rydberg interaction at the same time. As applications, we discuss in
detail the feasibility of preparing two-atom and three-atom entanglement with
ground-state blockade in closed system and open system, respectively, which
shows that a high fidelity of entangled state can be obtained with current
experimental parameters.

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