arXiv subjects

Nasser Metwally

Publications and source records attributed to Nasser Metwally.

At least 19 recordsLinked to original sources

arXiv2020

The concealment of accelerated information is possible

The possibility of masking an accelerated two-qubit system by using a minimum number of qubits is discussed. It is shown that, the information may be masked in either entangled local states or product non-local separable states. We examine that each partition of these states satisfies the masking conditions. Due to the presence of non-local separable partition, one may consider that it is a type of quantum data hiding scheme. The local /non-local information encoded in the masked entangled state is robust against the decoherence of the acceleration process. The possibility of estimating the acceleration parameter via the entangled/separable masked state increases as the initial entanglement value increases. The efficiency of the masking process is examined by quantifying the fidelity of the accelerated state and its subsystems. It is shown that, the fidelity of the masked state is maximum at small initial acceleration, while the minimum fidelity is more than $96\%$.

quant-ph↗

arXiv2020

Bidirectional Teleportation using Fisher Information

In this contribution, we reformulated the bidirectional teleportation protocol suggested in [7], by means of Bloch vectors as well as the local operations are represented by using Pauli operators. Analytical and numerical calculations for the teleported state and Fisher information are introduced. It is shown that both quantities depend on the initial state settings of the teleported qubits and their triggers. The Fidelities and the Fisher information of the bidirectionally teleported states are maximized when the qubit and its trigger are polarized in the same direction. The minimum values are predicted if both initial qubits have different polarization or non-zero phase. The maximum values of the Fidelity and the quantum Fisher information are the same, but they are predicted at different polarization angles. We display that the multi-parameter form is much better than the single parameter form, where it satisfies the bounds of classical, entangled systems and the uncertainty principle.

quant-ph↗

arXiv2016

Fisher information of two superconducting charge qubits under dephasing noisy

The dynamics of a charged two-qubit system prepared initially in a maximum entangled state is discussed, where each qubit interacts independently with a dephasing channel. The Fisher information is used to estimate the channel and the energy parameters. Moreover, the contribution from different parts of Fisher information is discussed. We show that, the degree of estimation of any parameter depends on the initial value of this parameter. It turns out that the upper bounds of Fisher information with respect to the dephasing parameter increase and that corresponding to coupling parameter decreases as the initial energy of each qubit increases.

quant-ph↗

arXiv2016

Enhancing entanglement, local and non-local information of accelerated two-qubit and two- qutrit systems via weak-reverse measurements

The possibility of recovering and protecting the entanglement of accelerated 2-qubit and 2-qutrit systems is discussed using weak-reverse measurements. The accelerated partial entangled states are more responsive to be protected than the accelerated maximum entangled states. The accelerated coded local information in qutrit system is more robust than that encoded in a 2-qubit system, and it can be conserved even for larger values of accelerations. Meanwhile, the non-accelerated information in qubit system is not affected by the local operation compared with that depicted on qutrit system. For larger values of accelerations, the weak-reverse measurements can improve the coherent information at the expanse of the accelerated information.

quant-ph↗

arXiv2015

Entanglement of simultaneous and non-simultaneous Accelerated Qubit-Qutrit systems

In this contribution, we investigate the entanglement behavior of a composite system consists of two different dimensional subsystems in non-inertial frames. In particular, we consider a composite system of qubit(two-dimensional) subsystem, and qutrit, (three-dimensional) subsystem. The degree of entanglement is quantified for different cases, where it is assumed that the two-subsystems are simultaneously or non- simultaneously accelerated. The entanglement decays as the acceleration of any subsystem increases.In general, the decay rate of entanglement increases as the dimensional of the accelerated subsystem increases. These results could be important in building an accelerated quantum network consists of different dimensions nodes.

quant-ph↗

arXiv2013

Single and double changes of Entanglement

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.

quant-ph↗

arXiv2012

Usefulness classes of travelling entangled channels in noninertial frames

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.

quant-ph↗

arXiv2011

Entangled Network and Quantum Communication

A theoretical scheme is introduced to generate entangled network via Dzyaloshinskii- Moriya (DM)interaction. The dynamics of entanglement generated between different nodes by direct or indirect interaction is investigated. It is shown that, the direction of (DM) interaction and the location of the nodes have a sensational effect on the degree of entanglement. We quantify the minimum entanglement generated between all the nodes. The upper and lower bound of the entanglement of the generated network depends on the direction of DM interaction and the repetition of the behavior depends on the strength of DM. The generated entangled nodes are used as quantum channel to perform quantum teleportation, where we show that the fidelity of teleporting unknown information between the network members depends on the location of the members.

quant-ph↗

arXiv2011

Dynamics of encrypted information in the presence of imperfect operations

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.

quant-ph↗

arXiv2010

Quantum dense coding over Bloch channels

Dynamics of coded information over Bloch channels is investigated for different values of the channel's parameters. We show that, the suppressing of the travelling coded information over Bloch channel can be increased by decreasing the equilibrium absolute value of information carrier and consequently decreasing the distilled information by eavesdropper. The amount of decoded information can be improved by increasing the equilibrium values of the two qubits and decreasing the ratio between longitudinal and transverse relaxation times. 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 this type of channels.

quant-ph↗

arXiv2010

Dynamics of information in the presence of deformation

The entanglement of atomic system consists of two atoms interacts with a deformed cavity mode is quantified by the means of Bloch vectors and the cross dyadic of the travelling state inside the cavity. For large value of the deformation the amplitude of Bloch vectors decrease very fast and consequently the traveling state turns into mixed state quickly. The generated entangled state is used as quantum channel to implement quantum teleportation protocol. It is shown that both of the deformed parameter and the number of photons inside the cavity play a central role on controlling the fidelity of the transmitted information.

quant-ph↗

arXiv2009

Communication via Quantum Neural Network

In this study, the partially entangled neural networks is used to transfer information between two neurons, where the original teleportation protocol is employed this for this purpose. The effect of the network strength on the fidelity of the transported information is investigated. We show that as the strength of the network increases, the accuracy of the transformed information increases. As a practical application, we consider the spread of swine flu virus between two equivalent tranches of the community. In this treatment two factors are considered, one for humanity and the other for influence factor. The likelihood of infection between different age group is investigated, where we show that the strength of the neural network and the degree of infection plays an important role on transferring infection between different age group. From theoretical point of view, we show that it is possible to control the spread of the virus by controlling the network parameter. Also, by using local rotation, one can decrease the rate of infection between the young.

physics.gen-ph↗

arXiv2009

Abruption decay of entanglement and quantum communication through noise channels

We investigate the dynamics of two qubits state through the Bloch channel. It is found that the degradation and sudden-death of the entanglement depend on the channel's parameters and the structure of the input state. Starting from partially entangled states as input state, the output states are more robust compared with those obtained from initial maximally entangled states. Also the survivability of entanglement increased as the absolute equilibrium values of the channel increased or the ratio between the longitudinal and transverse relaxation times gets smaller. Ability of using the output states as quantum channels to perform quantum teleportation is investigated. The idea that the useful output states are used to achieve the original quantum teleportation protocol is discussed.

quant-ph↗

arXiv2009

Information loss in local dissipation environments

The sensitivity of entanglement to the thermal and squeezed reservoirs' parameters is investigated regarding entanglement decay and what is called sudden-death of entanglement, ESD, for a system of two qubit pairs. The dynamics of information is investigated by means of the information disturbance and exchange information. We show that for squeezed reservoir, we can keep both of the entanglement and information survival for a long time. The sudden death of information is seen in the case of thermal reservoir.

quant-ph↗

arXiv2008

Dynamics of Bloch vectors and the channel capacity of a non identical charged qubit pair

We have considered a system of two superconducting charge qubits capacitively coupled to a microwave resonator. The dynamics of the Bloch vectors are investigated for different regimes. By means of the Bloch vectors and cross dyadic we quantify the degree of entanglement contained in the generated entangled state. We consider different values of the system parameters to discuss the dynamics of the channel capacity between the qubits. We show that there is an important role played by initial state settings, coupling constant and the mean photon number on generating entangled state with high degree of entanglement and high capacity.

quant-ph↗

arXiv2008

Quantum deficits and correlations of two superconducting charge qubits

Motivated by recent experiments [Pashkin et al. Nature, \textbf{421}, 823 (2003)] which showed coherent oscillations of two superconducting qubits system, we consider a system of two charge qubits coupled to a common stripline microwave resonator. We discuss the separable and entangled behavior as well as the quantum and classical information deficits. Numerical computation of these quantities for several regimes is performed. We find that for less entangled states the partner can extract much more information by means of classical communication and local operations

quant-ph↗

arXiv2008

More Efficient Purifying scheme via Controlled- Controlled NOT Gate

A new modified version of the Oxford purification protocol is proposed. This version is based on the controlled-controlled NOT gate instead of controlled NOT in the original one. Comparisons between the results of the new version and the original and an earlier modification are given. It is found that the new version converges faster and consumes fewer initial qubit pairs of low fidelity per final qubit pair of high fidelity.

quant-ph↗

arXiv2008

New aspects of the purity and information of an entangled qubit pair

In this article, we investigate the purity dynamics of entangled 2 two-level atoms interacting with a single quantized electromagnetic field. We show that the purity of the qubit pairs depends on the initial state of the atomic system. It is found that the superposition case is the best choice to generate entangled states with high purity and hence high entanglement. It is clear that the purity of one qubit can be purified at the expense of the other pair through the phenomena of purity swapping. The mean photon number plays an important role in increasing the purity. The robustness of the quantum channel is investigated in the presence of individual attacks, where we study the separability of these channels and evaluate its fidelity. Finally, we use the partial entangled states as quantum channels to perform the original coding protocol. We find that Bob can obtain the coded information with reasonable percentage. The inequality of security is tested, where we determine the interval of times in which Alice and Bob can communicatesecurely. These intervals depend on the type of error and the structure of the initial atomic system

quant-ph↗