The controlled quantum dense coding via a non-maximal entangled cluster state is investigated.It is shown that the supervisor can control the amount of information between the sender and the receiver,which is also the control of channel between Alice and Bob.
A controlled quantum dense coding protocol with GHZ-class state is proposed. In this case the sender (Alice) can send information to the receiver (Bob), whereas the supervisor (Cliff) can control the quantum channel between Alice and Bob via his local measurement. The amount of classical information is shown to be controlled by the supervisor through adjustments of the local measurement angles and depend on the coefficients of the original GHZ-class state. We also give two concrete methods for Alice to deal with one of Cliff's measurement result which is more complicated.
A scheme of controlled dense coding was proposed by using non-symmetric quantum channel in3×2×2 dimensional entangled state.The collapse of the state and entanglement between Alice and Bob were controlled by Charlie's local measurement on his particle in two dimension.Then the 3×2 dimensional non-symmetric quantum channel was controlled.It can be seen that the average amount of transmitted information of dense coding was controlled by Charlie's measurement angle.One can find that the average amount of information is more than 2 bits by using maximally entangled state in the non-symmetric quantum channel.Thus,this scheme is high-efficiency.In the case the entanglement is non-maximally,the transmitted information is determined by the measurement angle 6 and the coefficient /3 of the entangled state.
In quantum communication, the concept of dense coding traditionally relies on maximally entangled states as quantum channels. Recent advancements have expanded this framework to include non-maximally entangled states within the probabilistic dense coding paradigm. However, such schemes introduce a significant limitation: the receiver cannot always retrieve the complete dense coding information sent by the sender. Consequently, the receiver must inform the sender of the amount of information successfully received. Based on this feedback, the sender determines whether retransmission is necessary, leading to inefficient use of the quantum channel and reduced communication efficiency. To address these shortcomings, we propose an alternative deterministic quantum dense coding scheme that utilizes non-maximally entangled states as the quantum channel. This deterministic approach eliminates the need for retransmissions and significantly enhances communication efficiency while maintaining compatibility with non-maximally entangled states. Our scheme represents a substantial improvement over existing probabilistic methods and paves the way for more efficient quantum communication protocols.