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We present a scheme for the generation of a genuine four-atom entangled state in Cavity QED. This state has many interesting entanglement properties and wide applications in quantum information processing and fundamental tests of quantum physics. Our scheme is insensitive to both the cavity decay and the thermal field. [ABSTRACT FROM AUTHOR]

We propose a scheme for splitting an arbitrary two-qubit state among three parties by using a six-qubit cluster-class state as a quantum channel. Based on two Bell-state measurements (BSMs) and a two-qubit projective measurement, any one of the two agents can reconstruct the original state if he/she collaborates with the other one, whilst individual agent obtains no information. [ABSTRACT FROM AUTHOR]

We propose a scheme of controlled teleportation of an arbitrary three-qubit state by using a five-qubit cluster state. In our scheme, the sender Alice performs five sets of single-qubit measurements and the controller Charlie needs only take a single-qubit measurement. The receiver Bob can reconstruct the arbitrary three-qubit state by performing the single-qubit unitary operations and a controlled-NOT operation if he obtains the help of the controller. We show that the efficiency in this scheme approaches 100% [ABSTRACT FROM AUTHOR]

We propose a scheme of bidirectional controlled remote state preparation of an arbitrary two-qubit state, where a nine-qubit entangled state is used as the quantum channel. In our scheme, Alice and Bob can prepare simultaneously an arbitrary two-qubit state for each other's place with the help of the controller Charlie. The total success probability for our scheme reaches 100%. PACS numbers 03.67.Hk, 03.65.Ud, 42.50.Dv. [ABSTRACT FROM AUTHOR]

We propose a scheme of controlled cyclic quantum teleportation of an arbitrary two-qubit entangled state by using a ten-qubit entangled state. In our scheme, Alice can teleport an arbitrary two-qubit entangled state to Bob, Bob can teleport an arbitrary two-qubit entangled state to Charlie and at the same time Charlie can teleport an arbitrary two-qubit entangled state to Alice with the help of the controller David. [ABSTRACT FROM AUTHOR]

A scheme is presented to implement bidirectional controlled quantum teleportation (QT) by using a five-qubit entangled state as a quantum channel, where Alice may transmit an arbitrary single qubit state called qubit A to Bob and at the same time, Bob may also transmit an arbitrary single qubit state called qubit B to Alice via the control of the supervisor Charlie. Based on our channel, we explicitly show how the bidirectional controlled QT protocol works. By using this bidirectional controlled teleportation, espcially, a bidirectional controlled quantum secure direct communication (QSDC) protocol, i.e., the so-called controlled quantum dialogue, is further investigated. Under the situation of insuring the security of the quantum channel, Alice (Bob) encodes a secret message directly on a sequence of qubit states and transmits them to Bob (Alice) supervised by Charlie. Especially, the qubits carrying the secret message do not need to be transmitted in quantum channel. At last, we show this QSDC scheme may be determinate and secure. [ABSTRACT FROM AUTHOR]

We demonstrate that a genuine six-atom entangled state can be used to realize the deterministic quantum state sharing of an arbitrary two-atom state in cavity QED. In our scheme, any one of the two agents is sufficient to reconstruct the original state only under the condition that he/she obtains the help of the other one, but one of them obtains no information. The presented protocol is showed to be secure against certain eavesdropping attacks. [ABSTRACT FROM AUTHOR]

We present an experimentally feasible scheme for implementing controlled dense coding through a genuine five-atom entangled state in cavity QED. The scheme is insensitive to both the cavity decay and the thermal field. In the scheme that four-atom entangled states can be exactly distinguished with detecting the atomic state, and the controlled dense coding can be realized in a simple way. [ABSTRACT FROM AUTHOR]

A scheme for the controlled joint remote preparation of an arbitrary six-qubit cluster-type state by using only two sets of five-qubit GHZ states as quantum channel is proposed. In our scheme, Alice firstly performs two sets of two-qubit projective measurement according to the real coefficients and the complex coefficients of the desired six-qubit cluster-type state. Then, the controller Charlie must apply another two-qubit projective measurement according to the Alice's measurement result. Finally, Bob can obtain the desired six-qubit cluster-type state according to an appropriate unitary operation. Our scheme can achieve unit success probability. [ABSTRACT FROM AUTHOR]

We propose a scheme for implementing the deterministic quantum information splitting (QIS) of an arbitrary three-atom state in cavity QED. In the scheme, a four-atom χ-state and a three-atom GHZ state are used as quantum channel. In comparison with the QIS scheme by using the same quantum channel (Luo and Deng in Quantum. Inf. Process. 12:773, ), our scheme does not involve joint Bell-state measurements, one only needs to perform the single-atom measurements. Our scheme is not sensitive to both the cavity decay and the atom radiation, which is of importance in view of experiment. [ABSTRACT FROM AUTHOR]

We present a simple scheme for implementing controlled dense coding by using a five-atom cluster state. In cavity QED systems, we have proposed to generate a five-atom cluster state and demonstrated that the four-atom entangled states can be exactly distinguished. Thus our approach can be realized with present cavity QED techniques. [ABSTRACT FROM AUTHOR]

A new application of the genuinely entangled five-qubit state introduced by Brown et al. (J Phys A 38(5), 1119-1131, ) is investigated for quantum information splitting (QIS) of an arbitrary three-qubit state. We demonstrate that such a genuine five-qubit entangled state and a Bell-state can be used to realize the deterministic QIS of an arbitrary three-qubit state by performing the Bell-state measurements and single qubit measurement. The presented protocol is showed to be secure against certain eavesdropping attacks. [ABSTRACT FROM AUTHOR]

We demonstrate that a four-qubit cluster state can be used to realize the deterministic quantum state sharing (QSTS) of an arbitrary four-qubit GHZ-type state among three parties by introducing three ancillary qubits and performing three controlled-NOT operations. In our scheme, any one of the two agents has the ability to reconstruct the original state if he/she collaborates with the other one, whilst individual agent obtains no information. [ABSTRACT FROM AUTHOR]

A new application of the W-class state is investigated for teleportation of an arbitrary three-qubit state. We demonstrate that three sets of W-class states can be used to realize the perfect teleportation of an arbitrary three-qubit state by performing only the three-qubit von Neumann measurements and local unitary operations. [ABSTRACT FROM AUTHOR]

new application of the four-qubit cluster state is investigated for quantum information splitting (QIS) of an arbitrary N-qubit GHZ-type state among three parties. We demonstrate that a four-qubit cluster state can be used to realize the deterministic QIS of an arbitrary N-qubit GHZ-type state by introducing N−1 ancillary qubits and performing N−1 controlled-NOT operations. The presented protocols considered here are secure against certain eavesdropping attacks. [ABSTRACT FROM AUTHOR]

new application of the four-qubit cluster state is investigated for quantum information splitting (QIS) of an arbitrary three-qubit state. Muralidharan and Panigrahi (Phys Rev A 78:062333, 2008) argued that a four-qubit cluster state is impossible for QIS of an arbitrary two-qubit state. In this paper, we demonstrate that two four-qubit cluster states can be used to realize the deterministic QIS of an arbitrary three-qubit state by performing only the Bell-state measurements. Our scheme considered here is secure against certain eavesdropping attacks. [ABSTRACT FROM AUTHOR]

We demonstrate that a genuine six-qubit entangled state introduced by Tapiador et al. [J. Phys. A42 (2009) 415301] can be used to realize the deterministic controlled teleportation of an arbitrary three-qubit state by performing only the Bell-state measurements. [ABSTRACT FROM AUTHOR]

Abstract: A new application of the W-class state is investigated for quantum state sharing (QSTS) of an arbitrary three-qubit state. We demonstrate that four sets of W-class states can be used to realize the deterministic QSTS of an arbitrary three-qubit state based on the three-qubit von Neumann measurements and the local unitary operations. Our scheme considered here is secure against certain eavesdropping attacks. [ABSTRACT FROM AUTHOR]

new application of the genuinely entangled six-qubit state introduced recently by Borras et al. [J. Phys. A 40:13407, ] is investigated for the controlled teleportation of an arbitrary three-qubit state. In our scheme, a genuinely entangled six-qubit state and a Bell-state are shared by a sender (Alice), a controller (Charlie) and a receiver (Bob). Both the sender and the controller only need to perform Bell-state measurements (BSMs), the receiver can reconstruct the arbitrary three-qubit state by performing some appropriate unitary transformations on his qubits after he knows the measured results of both the sender and the controller. This controlled teleportation scheme is deterministic. [ABSTRACT FROM AUTHOR]