A scheme for controlled teleportation of an unknown N -qubit entangled GHZ state from the sender Alice to the distant receiver Bob is proposed. And m -qubit GHZ state is sufficient for the task of control by m spatially-separated supervisors. Conditioned on the local operations executed by all participants, Bob can faithfully restore the original state by performing relevant unitary transformations with the aid of some classical message about measurement results. Anyone's absence will absolutely lead to the failure of teleportation.
A scheme for controlled teleportation of an unknown N -qubit entangled GHZ state from the sender Alice to the distant receiver Bob is proposed. And m -qubit GHZ state is sufficient for the task of control by m spatially-separated supervisors. Conditioned on the local operations executed by all participants, Bob can faithfully restore the original state by performing relevant unitary transformations with the aid of some classical message about measurement results. Anyone's absence will absolutely lead to the failure of teleportation.
A scheme for teleporting an unknown three-qubit GHZ state under the control of many supervisors is presented.In order to realize the teleportation,the sender Alice needs to perform Bell state measurements on her qubit pairs and all the spatially-separated supervisors should make a Hadamard transformation and a Von Neumann measurement on their own qubit,respectively.Then the receiver Bob can restore the original state by operating some pauli matrixes with the aid of classical message from Alice and supervisors.Anyone's absence will surely fail the teleportotion.
A scheme for probabilistic controlled teleportation of a triplet W state from the sender Alice to the distant receiver Bob is proposed. In this scheme, an m -qubit GHZ state serves as the control parameter. The m control qubits are shared by m ( s 1 , s 2 . . . s m ) spatially-separated supervisors. With the aid of local operations and individual measurements, including Bell-state measurement, Von Neumann measurement, and mutual classical communication, etc., Bob can faithfully reconstruct the original state by performing relevant unitary transformations. However, even if one participant does not cooperate during the process, the receiver Bob cannot fully recover the original state. This protocol can be extended to probabilistic controlled teleportation of an arbitrary N -qubit state and some other N -qubit entangled states.
In this scheme, N non-maximally entangled particle pairs are used as quantum channel to teleport an unknown N -particle entangled GHZ state via entanglement swapping. In order to realize this teleportation, the sender Alice operates Bell-state measurement on particles belonging to herself. Then she informs the results to the receiver Bob through classical communication. According to the results, Bob operates corresponding transformation to reconstruct the initial state. The advantage of this scheme is that it needs only one common unitary matrix for Alice's different results, which has a more general meaning. As a special case, teleporting an unknown three-particle entangled GHZ state is proposed.
In the past decades, various schemes of teleportation of quantum states through different types of quantum channels (a prior shared entangled state between the sender and the receiver), e.g. EPR pairs, generalized Bell states, qubit GHZ states, standard W states and its variations, genuine multiqubit entanglement states, etc., have been developed. Recently, three-qutrit quantum states and two-qudit quantum states have also been considered as quantum channels for teleportation. In this paper, we investigate the teleportation of an unknown qudit using a d level GHZ state, i.e. a three-qudit maximally entangled state, as quantum channel. We design a general scheme of faithful teleportation of an unknown qudit using a d-level GHZ state shared between the sender and the receiver, or among the sender, the receiver and the controller; an unknown two-qudit of Schmidt form using a d level GHZ state shared between the sender and the receiver; as well as an unknown arbitrary two-qudit using two shared d level GHZ states between the sender, the receiver and the controller, or using one shared d level GHZ state and one shared generalized Bell state. We obtain the general formulas of Alice's measurement basis, Charlie's measurement basis and Bob's unitary operations to recover the input state of Alice. It is intuitionistic to generalize the protocols of teleporting an arbitrary two-qudit state to teleporting an arbitrary n-qudit state.
A scheme for generalized controlled teleportation of an arbitrary two-quNit entangled state with N -dimensional partially Greenberger–Horne–Zeilinger (GHZ) state is proposed. A generalized Bell state measurement (BM) and a single-particle measurement in high dimensions are needed. According to the sender Alice's classical message, the receiver Charlie can restore the unknown two-quNit state with a certain probability by introducing an additional particle and performing a controlled-not (C-NOT) operation on his particles if she cooperates with the controller Bob. The total success probability and classical communication cost are calculated. We also generalize the scheme to the case where there are K controllers. It is shown that any one of the receivers can reconstruct the unknown state if he/she cooperates with all the controllers.
A multiparty-controlled teleportation (M-CT) scheme for securely teleporting an arbitrary unknown single-qubit state by using generalised Greenberger-Horne-Zeilinger (GHZ) states is presented in this paper, i.e., a sender, Alice, transmits an arbitrary single-qubit state to a distant receiver, Bob, under approving by all N controllers Charliei(i = 1, 2, …, N) in a quantum communication network. It is proved feasibly and easily to realise by quantum entanglement. The security of proposed scheme is also discussed. We make sure of the security of the quantum channel between the parties by decoy states. This scheme also can be used to share a quantum secret information in quantum secret sharing.