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A system consists of two entangled qubits, where each qubit interacts locally with an environment described by a bosonic bath. The time evolution of the proposed system is obtained analytically by solving its Markovian master equation. The quantum Fisher information is used as an estimator of the phase damping of the initial state settings and the interaction damping parameter. It is exhibited that the initial state settings play a role as a controller of the precision of the estimation degree of these parameters. We classified the state that could be used to estimate the phase damping with high accuracy. Moreover, the constant behavior of the variances of the estimated parameters shows that the optimal estimation could be achieved for small values of the damping parameter. We have discussed the possibility that the amount of quantum Fisher information can be advised as an indicator of the presence of non-classical correlation between the subsystems of the entangled qubit.

In this paper, we give an exact general solution to the fractional Schrödinger equation of two interacting atoms. It consists of using the Riemann–Liouville fractional integral operator to examine the interaction between two identical atoms under temporal–fractional evolution. The dynamics of quantum Fisher information with respect to changes in the phase parameter and the quantum coherence by means of the l_1-norm and relative entropy of coherence are discussed. Moreover, the analytical fractional solution allows us to evaluate the relationship between the estimation precision of the phase parameter and the coherence measures for various atom–atom states. Indeed, the obtained results show a good similarity between these measures for certain critical values of the phase parameter. In addition, it is observed that initially, for such coherent-like fractional states, the amount of quantum Fisher information may be sensitive or insensitive to changes in the phase parameter. Therefore, one can conclude that quantum Fisher information can be considered as an indicator of quantum coherence in a composite quantum state.

A bidirectional quantum teleportation protocol is introduced over a quantum network consisting of more than four members sharing a coherent entangled state, where it is implemented in a perfect or noisy environment. The results show that the amplitude of the coherent state and the decoherence parameter play important roles in maximizing or minimizing this probability. At fixed values of the amplitude and decoherence parameters, the success of probability increases as the number of users increases. The fidelity of the teleported coherent state depends on the type of encoded information, whether entangled/partial or classical information, namely, it depends on the weight parameter. The stable behavior of the fidelity is displayed when users teleport classical information.

The memory fractional effects of a one-axis twisting model on the dynamics of two-qubit entanglement and non-locality are discussed. It consists of solving the time-dependent fractional Schrödinger equation by extending any integration into non-integer orders using Riemann–Liouville integration. The obtained results present the possibility of controlling the fractional order of memory, varying the parameters to significantly generate concurrency and Bell's non-locality. Under the current investigation setup, it is noticeable that the behaviors of the proposed quantifiers are similar to each other, but with a small difference in the amplitude of non-locality with respect to entanglement. Importantly, we show that the most intriguing aspect of this paper is to detect that pair-qubit entanglement and non-locality can be preserved for an indefinite time, which still holds significance in quantum information processing. • In this paper a model based on the interaction between two-qubit system by using twisting model. • We solved the fractional Schrödinger equation. • We studied concurrence, Bell non-locality and coherence. [ABSTRACT FROM AUTHOR]

We present a scheme for implementing a quantum teleportation process using the Jaynes–Cummings model. For this, we study the interaction between an excited state of a two-level atom and a single electromagnetic field in a superposition of coherent states. The resulting entangled state may be considered as a good quantum channel for quantum teleportation protocol. By controlling the interaction field parameters inside the cavity, the average fidelity of the teleported state may be maximized. However, the weight and phase parameters in the teleported states are estimated by using quantum Fisher information. It allows one to show that the sensitivity of the teleported states fluctuates between maximum and minimum bounds for large numbers of photons. Evaluating different quantities of quantum entanglement, average fidelity, and the amount of quantum Fisher information shows that the odd coherent states are usually larger than those obtained using even coherent states.

A fractional quantum state has created between two-qubit system by a Heisenberg X Y Z model in the presence of the Dzyaloshinskii–Moriya (DM) interaction. The impact of the initial state settings and the interaction parameters on the amount of the quantum correlation is discussed. We used the concurrence and local quantum uncertainty to quantify these correlations. It is shown that, both quantifiers increase suddenly/gradually depending on the order of the fractional state, and whether the system is ferromagnetic or anti-ferromagnetic. The fractional parameter may increase/ stabilized the memory of the generated fractional state. Small values of the DM interaction can maximize the initial quantum correlation of a partial entangled state. The possibility of using these fractional time-dependent states as quantum channels to perform quantum teleportation has examined. It is shown that, preparing the system in anti-ferromagnetic regime improves the fidelity of the teleported state. The strength of the DM interaction and the fractional's order has a clear effect on the fidelity's behavior, where they may be used as control parameters to increase the efficiency of the fractional quantum channel in the context of quantum communication. [ABSTRACT FROM AUTHOR]

Recently, Yang and Hwang [Int. J. Theor. Phys. 53, 224 (2014)] demonstrated that the scheme to share information via employing discrete algorithm to quantum states presented by Kang and Fang [Commun. Theor. Phys. 55, 239 (2011)] suffers from a major vulnerability allowing an eavesdropper to perform a measurement and resend attack. By introducing an additional checking state framework, the authors have proposed an improved protocol to overcome this weakness. This work calls into question the invoked vulnerability in order to clarify a misinterpretation in the same protocol stages also introduce a possible leakage information strategy, known as a faked state attack, despite the proposed improvement, which means that the same security problem may persist. Finally, an upgrading technic was introduced in order to enhance the security transmission.