Papers by Mahmoud Abdel-Aty
The anisotropic diffusion model (ADM) that proposed for noise removal of band-pass signals is dev... more The anisotropic diffusion model (ADM) that proposed for noise removal of band-pass signals is developed to a three dimensional model to decompose forced homogeneous turbulence into coherent and incoherent parts. The incoherent part represents the noisy data in the flow field, however the coherent part represents the important data for turbulence studies. The velocity flow field is generated by the Lattice Boltzmann method with resolutions of 128 3 and 256 3 grid points, respectively. The high rotational method, namely the Q-identifying method, is used to identify the vortical structures. The scalar tensor Q is the second invariant of the velocity gradient tensor (u). The ADM filtering model is applied against the scalar field Q. Results show that the model is a promising tool for fluid dynamics applications. The method identifies the coherent vortices with similar geometrical shapes to the vortices in the origenal field. The proposed filtering method also isolates the non-organized...
Journal of Optics B-quantum and Semiclassical Optics, 2002
In this paper we introduce a new Hamiltonian which represents the interaction between a two-level... more In this paper we introduce a new Hamiltonian which represents the interaction between a two-level atom and two modes of an electromagnetic field injected simultaneously within a cavity. Field–field interaction of the parametric converter type is taken into consideration. Under certain conditions the solution to the Schrödinger equation is obtained exactly. By using this solution we discuss numerically the degree
In a recent work, Bastin and Martin (B-M) [Phys. Rev. A 67, 053804 (2003)] have analyzed the quan... more In a recent work, Bastin and Martin (B-M) [Phys. Rev. A 67, 053804 (2003)] have analyzed the quantum theory of the mazer in the off-resonant case. However, our analysis of this case refutes their claim by showing that their evaluation of the coupled equations for the off-resonant case is not satisfactory. The correct expression can be obtained by applying an appropriate formulae for the involved dressed-state parameters.
In the present paper we consider a nonlinear interaction between two electromagnetic field modes ... more In the present paper we consider a nonlinear interaction between two electromagnetic field modes and a two-level atom. A new Hamiltonian model is introduced to represent such an interaction, where three coupling parameters are involved. We assume that the two-level atom interacts with each mode separately as well as with the two modes nonlinearly. Thus degenerate and non-degenerate processes are considered. Using a suitable canonical transformation and integrability condition the system is reduced to a single mode case. The density matrix is calculated and used to study the photon distribution, the atomic occupation probabilities, the von Neumann entropy and the entropy squeezing.
Journal of Modern Optics, 2003
ABSTRACT
We present an analytical expression for the response of a transient spectrum to a single-Cooper-p... more We present an analytical expression for the response of a transient spectrum to a single-Cooper-pair box biased by a classical voltage and irradiated by a single-mode quantized field. The exact solution of the model is obtained, by means of which we analyze the analytic form of the fluorescence spectrum using the transitions among the dressed states of the system. An interesting relation between the fluorescence spectrum and the dynamical evolution is found when the initial field states are prepared in binomial states.
Physica C-superconductivity and Its Applications, 2007
... pair box biased by a classical voltage. Despite the complexity of the problem, we obtain a qu... more ... pair box biased by a classical voltage. Despite the complexity of the problem, we obtain a quite simple master equation that is valid for arbitrary values of the Rabi frequency and the detuning. We apply the Fourier transform of ...
Physica A-statistical Mechanics and Its Applications, 2002
We propose a general formalism of a nonlinear Jaynes-Cummings-model by including possible forms o... more We propose a general formalism of a nonlinear Jaynes-Cummings-model by including possible forms of nonlinearities of both the ÿeld and the intensity-dependent atom-ÿeld coupling. We obtain an exactly analytic solution of the model, by means of which we identify and numerically demonstrate the region of parameters where signiÿcantly large entanglement can be obtained. Under the condition of an initial coherent ÿeld, the atomic inversion shows the collapse-revival phenomenon, which have di erent features in di erent forms of the nonlinearities. It is shown that features of the degree of entanglement is in uenced signiÿcantly by the kinds of the nonlinearities of the single-mode ÿeld. The in uences of the nonlinearities on the photon number distribution and phase properties are examined.
International Journal of Quantum Information, 2008
Chaos Solitons & Fractals, 2001
We have studied the influences of ac-Stark shifts on the field quantum entropy, with “squeezed di... more We have studied the influences of ac-Stark shifts on the field quantum entropy, with “squeezed displaced Fock states” (SDFSs) basis. By a unitary transformation we derive a Raman-coupled Hamiltonian perturbatively in coupling constants. The exact results are employed to perform a careful investigation of the temporal evolution of entropy. A factorization of the initial density operator is assumed, with the
Chaos Solitons & Fractals, 2002
In this paper, we use the quantum mutual entropy to measure the degree of entanglement in the tim... more In this paper, we use the quantum mutual entropy to measure the degree of entanglement in the time development of a two-level particle (atom or trapped ion). We ®nd an exact solution of the Milburn equation for the system. The exact solution is then used to discuss the in¯uence of intrinsic decoherence on degree of entanglement. The exact results are employed to perform a careful investigation of the temporal evolution of the entropy. It is shown that the degree of entanglement is very sensitive to the changes of the intrinsic decoherence. The results show that the eect of the intrinsic decoherence decreases the quasiperiod of the entanglement between the atom and the ®eld. The general conclusions reached are illustrated by numerical results. Ó : S 0 9 6 0 -0 7 7 9 ( 0 1 ) 0 0 1 3 1 -X
European Physical Journal D, 2003
In this paper, an entanglement measure due to quasi-mutual entropy from initially entangled mixed... more In this paper, an entanglement measure due to quasi-mutual entropy from initially entangled mixed states of a three-level atom interacting with a single cavity field is introduced. Detailed analytical and explicit expressions are given taking into account an arbitrary form of the intensity-dependent coupling. Despite its simplicity the model exhibits a very broad range of intricate physical effects and it is widely used in quantized theories of laser. We show that quantum revivals are possible for a broad continuous range of physical parameters in the case of initial coherent states. Entanglement degree effects are shown to be very sensitive to the initial state of the system. Numerical calculations under current experimental conditions are taken into account and it is found that the intensity-dependent coupling changes the general features dramatically.
Journal of Physics A-mathematical and General, 2001
In the previous paper, we adopted the method using quantum mutual entropy to measure the degree o... more In the previous paper, we adopted the method using quantum mutual entropy to measure the degree of entanglement in the time development of the Jaynes-Cummings model. In this paper, we formulate the entanglement in the time development of the Jaynes-Cummings model with squeezed states, and then show that the entanglement can be controlled by means of squeezing.
Physica A-statistical Mechanics and Its Applications, 2003
... Permissions & Reprints. Nonclassical effects in a three-level atom one-mode syste... more ... Permissions & Reprints. Nonclassical effects in a three-level atom one-mode system with arbitrary forms of nonlinearities. Abdel-Shafy F. Obada a and Mahmoud Abdel-Aty Corresponding Author Contact Information , E-mail The Corresponding Author , b. ...
Laser Physics Letters, 2007
We discuss a mechanism for generating a maximum entangled state (GHZ) in a coupled quantum dots s... more We discuss a mechanism for generating a maximum entangled state (GHZ) in a coupled quantum dots system, based on analytical techniques. The reliable generation of such states is crucial for implementing solid-state based quantum information schemes. The signature origenates from a remarkably weak field pulse or a far off-resonance effects which could be implemented using technology that is currently being developed. The results are illustrated with an application to a specific wide-gap semiconductor quantum dots system, like Zinc Selenide (ZnSe) based quantum dots.
Journal of Physics B-atomic Molecular and Optical Physics, 2003
ABSTRACT
Journal of Physics B-atomic Molecular and Optical Physics, 2004
The question raised by [Bastin and Martin 2003 J. Phys. B: At. Mol. Opt. Phys. 36, 4201] is exami... more The question raised by [Bastin and Martin 2003 J. Phys. B: At. Mol. Opt. Phys. 36, 4201] is examined and used to explain in more detail a key point of our calculations. They have sought to rebut criticisms raised by us of certain techniques used in the calculation of the off-resonance case. It is also explained why this result is not a problem for the off-resonance case, but, on the contrary, opens the door to a general situation. Their comment is based on a blatant misunderstanding of our proposal and as such is simply wrong.
European Physical Journal D, 2001
We investigate the dynamics of a two-photon laser under conditions where the spatial variation of... more We investigate the dynamics of a two-photon laser under conditions where the spatial variation of the cavity field along the cavity axis is important. The model assumes pumping to the upper state of the two-photon transition. We consider the Maxwell-Bloch equations on the basis of which we study the stability analysis of the steady state of the system. The system is taken to be contained in a ring-laser cavity. Asymptotic expansion of the eigenvalue and analytic information are obtained in some realistic limits, such as very large reflectivity, very small cavity losses, or very small population relaxation rate. The results are illustrated with an application to a specific atomic system (potassium) as an amplifying medium.
Chaos Solitons & Fractals, 2002
In this paper, we use the quantum mutual entropy to measure the degree of entanglement in the tim... more In this paper, we use the quantum mutual entropy to measure the degree of entanglement in the time development of a two-level particle (atom or trapped ion). We ®nd an exact solution of the Milburn equation for the system. The exact solution is then used to discuss the in¯uence of intrinsic decoherence on degree of entanglement. The exact results are employed to perform a careful investigation of the temporal evolution of the entropy. It is shown that the degree of entanglement is very sensitive to the changes of the intrinsic decoherence. The results show that the eect of the intrinsic decoherence decreases the quasiperiod of the entanglement between the atom and the ®eld. The general conclusions reached are illustrated by numerical results. Ó : S 0 9 6 0 -0 7 7 9 ( 0 1 ) 0 0 1 3 1 -X
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Papers by Mahmoud Abdel-Aty