Controlled Dense Coding between Multi-Parties

Controlled dense coding via multi-particles GHZ state and multi-particles GHZ-class state are exploited in this letter. The quantum channel and the amount of information between the senders and the receivers are controlled by the supervisor via his local measurement. The amount of information is determined by Charlie’s measurement in the former case of GHZ state, and also by the coefficients of the original GHZ-class state in the latter case.     

Scheme for Controlled Dense Coding via Cavity Decay

A scheme for controlled dense coding via cavity decay is proposed. In the scheme, two degenerate ground states of six-level atoms are used as the storage qubits and the leaky photons act as flying qubits. The system is robust against atomic spontaneous emissions and decoherence of cavity field. And the successful probability is nearly 1 with quantum nondemolition parity detectors and photon detectors, The scheme may be realized based on current technologies.     

Scheme for Implementing Quantum Dense Coding and Teleportation with Tripartite Entangled State in Cavity QED

In this paper, we present a peculiar tripartite entangled state that is inequivalent to both the GHZ state and the W state, and then propose to implement efficient quantum information processing such as quantum dense coding and teleportation with this entangled state in cavity QED. In this scheme the atoms interact with a highly detuned cavity field with the assistance of a strong classical driven field. It does not require the transfer of quantum information between the atomic system and the cavity, and then our scheme is insensitive to both the cavity decay and the thermal field.     

Controlled Dense Coding with Six-Qubit Cluster State

Two schemes, via generalized measurement and with entanglement concentration respectively, for controlled dense coding with a six-qubit cluster state are investigated in detail. In these protocols, the supervisor (Cliff) can control the average amount of information transmitted from the senders (Alice and David) to the receiver (Bob) by adjusting the local measurement angle θ. It is shown that the results for the average amounts of information are unique from the different two schemes.     

Controlled Dense Coding with Four-Qubit Entangled State

Two schemes, via generalized measurement and with entanglement concentration respectively, for controlled dense coding with a four-qubit entangled state are investigated in detail. In the two schemes, the supervisor (Cliff) can control the average amount of information transmitted from the sender (Alice) to the receiver (Bob) by adjusting the local measurement angle θ. It is shown that the results for the average amounts of information are unique from the different two schemes.     

Controlled Dense Coding with Four-Particle Entangled State

Two schemes, via generalized measurement and entanglement concentration respectively, for dense coding are investigated by using a four-particle entangled state, in which the supervisor can control the average amount of information transmitted from the sender to the receiver by adjusting the local measurement angle. It is shown that the results for the average amounts of information are unique from the different two schemes.     

Controlled Dense Coding with Five-Qubit Cluster State

Two schemes, via entanglement concentration and with generalized measurement respectively, for controlled dense coding with a one-dimensional five-qubit cluster state are investigated. In this protocol, the supervisor (Cliff) can control the entanglement of the channel and the average amount of information transmitted from the sender (Alice) to the receiver (Bob) by adjusting the local measurement angle θ. It is shown that the results for the average amounts of information are unique from the different two schemes.     

Quantum Dense Coding Without Joint Measurement

We propose two schemes for quantum dense coding without Bell states measurement. One is deterministic, the other is probabilistic. In the deterministic scheme, the initial entangled state will be not destructed. In the proba-bilistic scheme, the initial unknown nonmaximal entangled state will be transformed into a maximal entangled one. Our schemes require two auxiliary particles and perform single-qubit measurements on them. Thus our schemes are simple and economic.     

Controlled Dense Coding using Generalized GHZ-type State

Two schemes for controlled dense coding with a extended GHZ-type state are investigated. In this protocol, the supervisor (Cliff) can control the channel and the average amount of information transmitted from the sender (Alice) to the receiver (Bob) by adjusting the local measurement angle θ. It is shown that the results for the average amounts of information are unique from the different two schemes.     

Controlled Dense Coding with a Four-Particle Non-maximally Entangled State

Two schemes for controlled dense coding with a four-particle entangled state are investigated, one with entanglement concentration and the other with generalized measurement. In these protocols, the supervisor (Cliff) can control the average amount of information transmitted from the sender (Alice and David) to the receiver (Bob) only by adjusting his local measurement angle θ. It is shown that the results for the average amounts of information are unique from the different two schemes.     

用三比特海森堡XXZ模型实现量子稠密编码

本文主要研究利用各向异性三比特海森堡XXZ模型实现量子稠密编码的理论可行性问题并讨论在有限温度下,xy平面上的耦合常数J,z方向的耦合常数Jz,以及外加磁场对稠密编码信道容量的影响。结果表明,耦合常数J对量子稠密编码信道容量起到积极作用。尽管耦合常数Jz,外加磁场B及温度T均抑制量子稠密编码的信道容量,但是在一定范围内J总可以抵消这些参数的消极作用并提高信道容量。     

Controlled Dense Coding by Using GHZ-Type State in Cavity QED

We present an experimentally feasible protocol for implementing controlled dense coding by using a three-atom GHZ-type state in cavity quantum electrodynamics (QED). In cavity QED system, we have proposed to generate a three-atom GHZ-type state and demonstrated that the probability of implementing controlled dense coding is 100 %. In addition, our approach can be realized with present cavity QED techniques.     

Controlled Dense Coding Through a Genuine Five-Atom Entangled State in Cavity QED

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.     

Dense Coding with Cluster State Via Local Measurements

Two schemes, introducing generalized measurement and entanglement concentration respectively, for dense coding are investigated by using a one-dimensional four-particle cluster state, where the supervisors (Cliff and David) can control the average amount of information transmitted from the sender (Alice) to the receiver (Bob) by adjusting the local measurement angles θ ₃ and θ ₄. It is shown that the results for the average amounts of information are unique from the different two schemes.     

Dense Coding with Extended GHZ-W State via Local Measurements

Two schemes, with entanglement concentration and via generalized measurement, for dense coding are investigated by using a extended four-qubit GHZ-W state, where the supervisors (David and Cliff) can control the average amount of information transmitted from the sender (Alice) to the receiver (Bob) by adjusting the measurement angles θ ₃ and θ ₄. We show that the results for the average amounts of information are unique from the different two schemes.     

Dense Coding via Local Measurement with Extended GHZ-Type State

Two schemes for dense coding via local measurement with an extended GHZ-type state are investigated. In this protocol, the supervisor (Cliff) can control the channel and the average amount of information transmitted from the sender (Alice) to the receiver (Bob) by adjusting the local measurement angle θ. It is shown that the results for the average amounts of information are unique from the different two schemes.     

Dense Coding with Nonmaximally Entangled Cluster State via Local Measurement

We present two schemes for dense coding with nonmaximally entangled cluster state via local measurement. The average amounts of information are unique from the different two schemes. The average amount of information transmitted from Alice to Bob depends not only on the measurement angle θ, but also on the superposition coefficients of the state. For a given nonmaximally entangled cluster state, the supervisor can control the average amount of information transmitted from the sender to the receiver by adjusting the measurement angle.