N. Metwally

Aswan University, Assuan, Aswān, Egypt

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Publications (39)35.5 Total impact

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    N. Metwally
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    ABSTRACT: The entanglement behavior of two classes of multi-qubit system, GHZ and GHZ like states passing through a generalized amplitude damping channel is discussed. Despite this channel causes degradation of the entangled properties and consequently their abilities to perform quantum teleportation, one can always improve the lower values of the entanglement and the fidelity of the teleportrd state by controlling on Bell measurements, analyzer angle and channel's strength. Using GHZ-like state within a generalized amplitude damping channel is much better than using the normal GHZ-state, where the decay rate of entanglement and the fidelity of the teleported states are smaller than those depicted for GHZ state.
    01/2014;
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    N. Metwally, H. Eleuch, M. Abdel-Aty
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    ABSTRACT: In the context of quantum information, we investigate extensively some important classes of a general form of a two-qubit system under Lorentz transformation. It is shown Lorentz transformation causes a decay of entanglement and consequently information loses. On the other hand, it generates entangled states between systems prepared initially in a separable states. The partial entangled states are more robust under Lorentz transformation than maximally entangled states. Therefore the rate of information lose is larger for maximum entangled states compared with that for partially entangled states.
    Communications in Theoretical Physics 01/2014; 61(1):32. · 0.95 Impact Factor
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    Nasser Metwally
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    ABSTRACT: Entanglement behavior for different classes of two qubit systems passing through a generalized amplitude damping channel is discussed. The phenomena of sudden single, double changes and the sudden death of entanglement are reported for correlated and non- correlated noise. It is shown that, for less entangled states, these phenomena appear for small values of channel strength. The effect of the channel can be frozen for these classes as one increases the channel strength. Maximum entangled states are more fragile than partial entangled states, where the entanglement decays very fast. However, one can not freeze the effect of the noise channel for systems initially prepared in maximum entangled states. The decay rate of entanglement for systems affected by non-correlated noise is much larger than that affected by correlated noise.
    Journal of the Optical Society of America B 12/2013; 31(4). · 2.21 Impact Factor
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    N. Metwally, H. A. Batarfi, S. S. Hassan
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    ABSTRACT: The entanglement of different classes of initially entangled qubit pair is investigated in the presence of short laser pulses of rectangular and exponential shapes with either one or both qubits are excited. For the rectangular pulse, the detuning parameter protects the entanglement from degradation and controls its upper and lower bounds. We show that the upper bounds of entanglement decrease if both particles are excited, but the lower bounds are much better if only one particle is excited. The phenomena of entanglement degradation, sudden- death and -birth are shown for small initial time. Long -lived entanglement behavior, but with a variable degree, appears in the presence of rectangular pulse. However, in the case of the exponential pulse one obtains an invariably long- lived entanglement. For the combined case (rectangular $+$ exponential), we show that one can generate a long-lived entanglement with small variable by increasing the strength of the rectangular pulse area and decreasing the Rabi frequency of the exponential pulse.
    International Journal of Quantum Information 11/2013; 12(01). · 0.92 Impact Factor
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    N. Metwally
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    ABSTRACT: Effect of Lorentz transformation on some properties of multi-qubit systems is investigated. It is shown that, properties like, the fidelity and entanglement decay as the Wigner's angles increase, but can be improved, if all the transformed particles are transformed with the same Wigner's angles. The upper bounds of the average capacity of the GHZ state increases while it decreases and more robust with the W-state as the Wigner's angle of the observer decreases. Under Lorentz transformation, the tripartite states transform into another equivalent states and hence no change on the efficiency of these states to perform quantum information tasks.
    10/2013;
  • A. El Allati, Y. Hassouni, N. Metwally
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    ABSTRACT: The possibility of generating entangled network via Dzyaloshinskii–Moriya interaction is investigated. The entanglement between the different nodes is quantified. This entangled network is employed to send information between different users who are members on this network. The effect of the field strength and the magnetic field parameters on the degree of entanglement of the network and the average fidelity is discussed. We show that by controlling these parameters one can maximize the average fidelity of the teleported state.
    International Journal of Quantum Information 07/2013; 11(03). · 0.92 Impact Factor
  • N. Metwally, M. Abdel-Aty, A.-S. Obada
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    ABSTRACT: We analyze a crucial effect of the spin-path environment on a single and maximum entangled two-qubit systems. For a single qubit, we investigate the coherent loss by means of coherent-vectors' dynamics and the interacted qubits' fidelity. We used entanglement and population dynamics to investigate the coherent loss of the two-qubit system. We show and numerically verify that the effect of the detuning and coupling parameters in the negativity can be mapped onto the maximum and minimum values of the entanglement.
    International Journal of Modern Physics B 07/2013; 27(17):50076-. · 0.46 Impact Factor
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    N. Metwally, A. Sagheer
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    ABSTRACT: The capacity of accelerated channel is investigated for different classes of initial states. It is shown that, the capacities of the travelling channels depend on the frame in which the accelerated channels are observed in and the initial shared state between the partners. In some frames, the capacities decay as the accelerations of both qubit increase. The decay rate is larger if the partners are initially share a maximum entangled state. The possibility of using the accelerated quantum channels to perform quantum coding protocol is discussed. The amount of decoded information is quantified for different cases, where it decays as the partner's accelerations increase to reach its minimum bound. This minimum bound depends on the initial shared states and it is large for maximum entangled state.
    Quantum Information Processing 02/2013; · 1.75 Impact Factor
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    N. Metwally, S. S. Hassan
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    ABSTRACT: We investigate the transfer and exchange information between a single qubit system excited by a rectangular pulse. The dynamics of the system is treated within and outside rotating wave approximation (RWA). The initial state of the qubit plays an important role for sending information with high fidelity. Within RWA, and as the fidelity of the transformed information increases the exchange information with the environment increases. For increasing values of atomic detuning, the fidelity decreases faster and the exchange information has an upper limit. Outside RWA,the fidelity of the transformed information increases as one increases the perturbation parameter. However the exchange information is very high compared with that within RWA. The orthogonality speed of the travelling qubit is investigated for different classes of initial atomic state settings and field parameters.
    10/2012;
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    N. Metwally, A. Al-Mannai, M. Abdel-Aty
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    ABSTRACT: The dynamics of the skew information (SI) is investigated for a single Cooper Pair Box,CPB interacts with a single cavity mode. The effect of the cavity and CPB's parameters on the SI is discussed. We show that, it is possible to increase the skew information to reach its maximum value either by increasing the number of photons inside the cavity or considering non-resonant case with larger detuning parameter. The effect of the relative ratio of Josephson junction capacity and the gate capacity is investigated, where the number of oscillations of the skew information increases by decreasing this ratio and consequently the travelling time between the maximum and minimum values decreases.
    Communications in Theoretical Physics 10/2012; 59(6). · 0.95 Impact Factor
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    ABSTRACT: In this paper, we investigate the dynamics of coded information in a single Cooper pair interacting with a single Cavity mode. The effect of the relative ratio of Josephson junction capacity and the gate capacities on the purity, coherent vectors and the entropy of the traveling Cooper pair are investigated. The exchange information between the environment and the Cooper pair is quantified for different values of the Cooper qubit and environment parameters.
    International Journal of Theoretical Physics 10/2012; · 1.09 Impact Factor
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    A.-S.F. Obadaa, N.M. Arafab, N. Metwally
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    ABSTRACT: We investigate the entanglement dynamics of maximum and partial entangled two-qubit states, where each qubit interacts locally with its own noise environment. In the presence of local non-correlated noise, the entangled system loses its entangled properties faster than that depicted for correlated noise. The capacity of the output channel decays gradually and smoothly in the presence of non-correlated noise and hastily for the correlated one. We show that the local non-correlated noise can improve the capacity of the output channel. The possibility of using the output state to perform quantum teleportation is discussed and the effect of the noise parameter on the fidelity of the teleported state is investigated.
    Journal of the Association of Arab Universities for Basic and Applied Sciences. 10/2012; 12(1):55.
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    A-H. M. Ahmed, Nordin Zakaria, Nasser. Metwally
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    ABSTRACT: The process of teleport information remotely in presence of an error in the implementation of the local operations as CNOT and Hadamard gate at the sending station is discussed. Through the control of the laboratory equipment the errors in the achieving the local operations could be resisted. The imperfect CNOT gates performance could be improved as the error’s strength in implementing of the Hadamard gate increases. It is shown that the accuracy of the information transfer not only depends on the laboratory equipment, but also on nature of the information to be teleported.
    Applied Mathematics & Information Sciences 09/2012; 6(3):781-787. · 0.73 Impact Factor
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    N. Metwally
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    ABSTRACT: A theoretical quantum teleportation protocal is suggested to teleport accelerated and non-accelerated information over different classes of accelerated quantum channels. For the accelerated information, it is shown that the fidelity of the teleported state increases as the entanglement of the initial quantum channel increases. However as the difference between the accelerated channel and the accelerated information decreases the fidelity increases. The fidelity of the non accelerated information increases as the entanglement of the initial quantum channel increases, while the accelerations of the quantum channel has a little effect. The possibility of sending quantum information over accelerated quantum channels is much better than sending classical information.
    Journal of the Optical Society of America B 06/2012; 30(1). · 2.21 Impact Factor
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    ABSTRACT: We investigate the linear entropy of a degenerate Raman process involving two degenerate Rydberg energy levels of an atom interacting with a cavity field. It is shown that a long living entanglement can be obtained for particular initial state settings. We demonstrate how these states can be observed experimentally and study the feasibility of the implementation with present day technology.
    AIP Con Pro; 06/2012
  • N. Metwally
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    ABSTRACT: The original dense coding protocol is achieved via quantum channel generated between a single Cooper pair and a cavity. The dynamics of the coded and decoded information are investigated for different values of the channel's parameters. The efficiency of this channel for coding and decoding information depends on the initial state settings of the Cooper pair. It is shown that, these information increase as the detuning parameter increases or the number of photons inside the cavity decreases. The coded and decoded information increase as the ratio of the capacities between the box and gate decreases. In the presence of imperfect operation, the sensitivity of the information to the phase error is much larger than the bit flip error.
    Journal of the Optical Society of America B 03/2012; 29(3):389-. · 2.21 Impact Factor
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    A. El Allati, Y. Hassouni, N. Metwally
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    ABSTRACT: The dynamics of maximum entangled coherent state travels through an amplitude damping channel is investigated. For small values of the transmissivity rate the travelling state is very fragile to this noise channel, where it suffers from the phase flip error with high probability. The entanglement decays smoothly for larger values of the transmissivity rate and speedily for smaller values of this rate. As the number of modes increases, the travelling state over this noise channel loses its entanglement hastily. The odd and even states vanish at the same value of the field intensity.
    Chinese Physics B 02/2012; 20(11). · 1.15 Impact Factor
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    Nasser Metwally
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    ABSTRACT: The dynamics of a general two qubits system in noninetrial frame is investigated analytically, where it is assumed that both of its subsystems are differently accelerated. Two classes of initial travelling states are considered:self transposed and a generic pure states. The entanglement contained in all possible generated entangled channels between the qubits and their Anti-qubits is quantified. The usefulness of the travelling channels as quantum channels to perform quantum teleportation is investigated. For the self transposed classes, we show that the generalized Werner state is the most robust class. We show that starting from a class of pure state, one can generate entangled channels more robust than self transposed classes.
    International Journal of Modern Physics B 01/2012; · 0.46 Impact Factor
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    ABSTRACT: The speed of computations is investigated by means of the orthogonality speed for a charged qubit interacting with a single cavity field prepared initially in a Fock state or Binomial state. We observe that the rate of the computational speed is related to the number of photons inside the cavity. Moreover, we show that the qubit-field coupling plays an opposite role, where the speed of computations is decreased as the coupling is increased. We suggest using the number of photons in the field as a control parameter to improve the speed of computations.
    Physica E Low-dimensional Systems and Nanostructures 07/2011; 43(10). · 1.86 Impact Factor
  • N Metwally
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    ABSTRACT: Dynamics of coded information over Bloch channels is investigated. We show that the coded information is sent with high accuracy over the Bloch channel by increasing the absolute equilibrium value of the information carrier or decreasing the ratio of relaxation time. The robustness of coded information in maximum and partial entangled states is discussed. It is shown that, the maximum entangled states are more robust than the partial entangled state over these types of channels. The dynamics of the local and the non-local information is investigated for different values of the channel's parameters and the initial state setting. It is found that by increasing the absolute equilibrium values for both qubits, the local information of both qubits decreases faster and consequently the information gained by the eavesdropper increases.
    Journal of Physics A Mathematical and Theoretical 01/2011; 44(5):055305. · 1.77 Impact Factor

Publication Stats

56 Citations
35.50 Total Impact Points

Institutions

  • 2014
    • Aswan University
      Assuan, Aswān, Egypt
  • 2008–2013
    • University of Bahrain
      • Department of Mathematics
      Al Manāmah, Capital, Bahrain
  • 2012
    • University Mohammed V Agdal
      Rabat, Rabat-Salé-Zemmour-Zaër, Morocco
  • 2004–2012
    • South Valley University
      • Department of Mathematics
      Al Uqşur, Muḩāfaz̧at al Uqşur, Egypt
  • 2005
    • Al-Azhar University
      • Department of Mathematics
      Cairo, Muhafazat al Qahirah, Egypt