Controlled remote preparation of an arbitrary four-qubit cluster-type state

Two schemes are proposed to realize the controlled remote preparation of an arbitrary four-qubit cluster-type state via a partially entangled channel. We construct ingenious measurement bases at the sender’s and the controller’s locations, which play a decisive role in the proposed schemes. The success probabilities can reach 50% and 100%, respectively. Compared with the previous proposals, the success probabilities are independent of the coefficients of the entangled channel.

Controlled Remote State Preparation

We present a scheme for remotely preparing a state via the controls of many agents in a network.In thescheme,the agents' controls are achieved by utilizing quantum key distribution.Generally,the original state can berestored by the receiver with probability 1/2 if all the agents collaborate.However,for certain type of original states therestoration probability is unit.

Controlled cyclic remote preparation

Multi-party quantum communication has gradually attracted widespread attention.To realize the perfect transmission of quantum states among multiple participants,a novel multi-party controlled cyclic remote preparation protocol for arbitrary single-qubit states with three senders is proposed.With the permission of one controller,each sender can transmit an arbitrary singlequbit state to its neighbor.In addition,we give a universal protocol for multi-party controlled cyclic remote preparation of arbitrary single-qubit states in the case of multiple senders,which can realize deterministic cyclic preparation of multiple quantum states in one direction.The scheme shows that the communication task can be successfully achieved only if all senders cooperate with the controller,and there is no need for the senders to employ information splitting and additional operations before performing measurements.Finally,we discuss the cyclic remote preparation protocol with three senders under five types of noisy environment,and the closeness between the output state and original state is measured by calculating fidelity.

Controlled Remote Preparing of an Arbitrary 2-Qudit State with Two-Particle Entanglements and Positive Operator-Valued Measure

We present a scheme for symmetric controlled remote preparation of an arbitrary 2-qudit state form a sender to either of the two receivers via positive operator-valued measurement and pure entangled two-particle states. The first sender transforms the quantum channel shared by all the agents via POVM according to her knowledge of prepared state. All the senders perform singIe- or two-particle projective measurements on their entangled particles and the receiver can probabilisticaly reconstruct the original state on her entangled particles via unitary transformation and auxiliary qubit. The scheme is optimal as the probability which the receiver prepares the original state equals to the entanglement of the quantum channel. Moreover, it is more convenience in application than others as it requires only two-particle entanglements for preparing an arbitrary two-qudit state.