We investigate the joint effects of phase decoherence, Dzyaloshinskii Moriya （DM） interaction and inhomogeneity of the external magnetic field （b） on dense coding in a two-qubit anisotropic Heisenberg XYZ spin cha...
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We investigate the joint effects of phase decoherence, Dzyaloshinskii Moriya （DM） interaction and inhomogeneity of the external magnetic field （b） on dense coding in a two-qubit anisotropic Heisenberg XYZ spin chain. Analytical expressions are obtained for the dense coding capacity. It is found that valid dense coding is always possible with this model when the system is initially prepared in the maximum entangled state. Moreover, optimal dense coding can be implemented for this initial state as long as the mean spin-spin coupling constant J＋ of the XY plane is larger than b and the DM interaction despite the intrinsic decoherence. Non-maximal entangled initial states are found to be undesirable for dense coding with this model.
We study dense coding under the condition that the sender's encoding operations be imperfect. In order to formally describe the effect of the imperfect encoding operations, we use four kinds of quantum noise proce...
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We study dense coding under the condition that the sender's encoding operations be imperfect. In order to formally describe the effect of the imperfect encoding operations, we use four kinds of quantum noise processes. In this way, the imperfect operation is the corresponding perfect operation followed by a quantum noise process. We show the relation among the average probability of decoding the correct information, the non-maximally entangled state, the imperfect encoding operations, and the receiver's measurement basis.
Quantum dense coding in a two-spin squeezing model under intrinsic decoherence with different initial states (Werner state and Bell state) is investigated. It shows that dense coding capacity chi oscillates with time ...
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Quantum dense coding in a two-spin squeezing model under intrinsic decoherence with different initial states (Werner state and Bell state) is investigated. It shows that dense coding capacity chi oscillates with time and finally reaches different stable values. chi can be enhanced by decreasing the magnetic field Omega and the intrinsic decoherence gamma or increasing the squeezing interaction mu, moreover, one can obtain a valid dense coding capacity (chi satisfies chi > 1) by modulating these parameters. The stable value of chi reveals that the decoherence cannot entirely destroy the dense coding capacity. In addition, decreasing Omega or increasing mu can not only enhance the stable value of chi but also impair the effects of decoherence. As the initial state is the Werner state, the purity r of initial state plays a key role in adjusting the value of dense coding capacity, chi can be significantly increased by improving the purity of initial state. For the initial state is Bell state, the large spin squeezing interaction compared with the magnetic field guarantees the optimal dense coding. One cannot always achieve a valid dense coding capacity for the Werner state, while for the Bell state, the dense coding capacity chi remains stuck at the range of greater than 1.
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 avera...
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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 theta (3) and theta (4). We show that the results for the average amounts of information are unique from the different two schemes.
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 ...
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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 theta(3) and theta(4). It is shown that the results for the average amounts of information are unique from the different two schemes.
Quantum entanglement may be used to increase the classical information capacity of a quantum channel. The capacity of dense coding using entangled input states though a noiseless channel is shown to be no better than ...
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Quantum entanglement may be used to increase the classical information capacity of a quantum channel. The capacity of dense coding using entangled input states though a noiseless channel is shown to be no better than the capacity for product input states, when using a pure entanglement resource. (C) 2001 Elsevier Science B.V. All rights reserved.
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 ...
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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 theta, 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.
We propose a multi-bit dense coding scheme by using only an Einstein-Podolsky-Rosen（EPR） channel and assistant *** is shown that no matter how many classical bits there are,the quantum channel is always a Bell *** p...
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We propose a multi-bit dense coding scheme by using only an Einstein-Podolsky-Rosen（EPR） channel and assistant *** is shown that no matter how many classical bits there are,the quantum channel is always a Bell *** present dense coding process can also prepare non-local multi-particle Greenberger-Horne-Zeilinger（GHZ） states at one of the *** quantum circuits for this dense coding process are constructed,the deterministic implementation method in an optical system based on the cross-Kerr nonlinearities is shown.
A quantum steganography protocol with a large payload is proposed based on the dense coding and the entanglement swapping of the Greenberger-Horne-Zeilinger （GHZ） states. Its super quantum channel is formed by build...
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A quantum steganography protocol with a large payload is proposed based on the dense coding and the entanglement swapping of the Greenberger-Horne-Zeilinger （GHZ） states. Its super quantum channel is formed by building up a hidden channel within the original quantum secure direct communication （QSDC） scheme. Based on the original QSDC, secret messages are transmitted by integrating the dense coding and the entanglement swapping of the GHZ states. The capacity of the super quantum channel achieves six bits per round covert communication, much higher than the previous quantum steganography protocols. Its imperceptibility is good, since the information and the secret messages can be regarded to be random or pseudo-random. Moreover, its security is proved to be reliable.
This paper reports that a quantum dense coding can be implemented with ions confined in a linear trap and interacting with laser beams. The scheme is insensitive to the interaction between the quantum channel and the ...
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This paper reports that a quantum dense coding can be implemented with ions confined in a linear trap and interacting with laser beams. The scheme is insensitive to the interaction between the quantum channel and the environment. The Bell-state measurement is not involved and the probability of success in our scheme is 1.0.
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