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A double Tavis-Cummings model (DTCM) is developed to simulate the entanglement dynamics of realistic quantum information processing where two entangled atom-pairs AB and CD are distributed in such a way that atoms AC are embedded in a cavity a while BD are located in another remote cavity b. The evolutions of different types of initially shared entanglement of atoms are studied under various initial states of cavity fields. The results obtained in the DTCM are compared with that obtained in the double Jaynes-Cummings model (DJCM) [M. Yönaç, T. Yu, J.H. Eberly, J. Phys. B 40, S45 (2007)] and an interaction strength theory is proposed to explain the parameter domain in which the so-called entanglement sudden death occurs for both the DTCM and DJCM. [ABSTRACT FROM AUTHOR]

A nontrivial protocol for teleporting an unknown N-qubit W-like state is proposed. The consumed resource is only ( N-1) shared ebits and 2( N-1) bits of classical communication, while the technique involves only controlled-NOT gates and single-qubit measurements/operations. The rule for reconstruction of the desired state at the receiving station is worked out explicitly in the most general case of an arbitrary N ≥ 3. The protocol is within the reach of present technologies. [ABSTRACT FROM AUTHOR]

We explicitly present a scheme for quantum state sharing of an arbitrary multiqubit state using nonmaximally entangled GHZ states as the quantum channel and generalized Bell states as the measurement basis. The scheme succeeds only probabilistically with its total success probability depending on the degree of entanglement matching between the quantum channel and the generalized Bell states. Security of the scheme is guaranteed by the fact that attacks of an outside eavesdropper or/and an inside dishonest party will inevitably introduce detectable errors. [ABSTRACT FROM AUTHOR]