This paper investigates the evolution and protection of quantum correlations (entanglement and qu... more This paper investigates the evolution and protection of quantum correlations (entanglement and quantum discord (QD) in particular), in a hybrid system formed by a qubit subjected to an external random field and a qutrit subjected to a colored noise generated either by a single or collection of many random bistable fluctuators (RBFs). Two different input states namely the one-and two-parameter class of states of qubitqutrit are investigated. Entanglement and QD are quantified by means of negativity and geometric QD and their protection investigated by recourse to the weak measurement (WM) and weak measurement reversal (WMR) technique. It is shown that the immunity of entanglement and QD against decoherence can be efficiently increased by properly adjusting the parameters of the input states, no matter the spectrum of the colored noise and the number of RBFs considered. Moreover, it is shown that the WM and WMR technique fails in protecting entanglement in the studied system, but can effectively protect QD from the detrimental impacts of the decoherence. In fact, it is shown that performing a WM followed by a WMR on the qubit of the system allows to shield the QD of the system from decoherence even when the decoherence process is strengthen by considering a large number of RBFs affecting the qutrit.
International Journal of Theoretical Physics, 2019
We use a system of three non-interacting qubits as a quantum probe to classify three classical no... more We use a system of three non-interacting qubits as a quantum probe to classify three classical non-Gaussian noises (namely the static, colored (pink and brown) and random telegraph noise), according to their detrimental effects on the evolution of entanglement of the latter. The probe system is initially prepared in the GHZ state and coupled to the noises in independent environments. Seven configurations for the qubit-noise coupling (QNC) are considered. To estimate the destructive influence of each kind of noise, we employ the tripartite negativity to compare the evolution of entanglement in these QNC configurations to each other with the same noise parameters. The results show that the evolution of entanglement is drastically impacted by the QNC configuration considered as well as the properties of the environmental noises and that the SN is more detrimental to the survival of entanglement than the RTN and CN, regardless of the Markov or non-Markov character of the RTN and the color of the CN. We also observed that pink noise is more fatal to the system than the RTN and that the situation is totally reversed in the case of brown noise. Finally, we show that these noises, in descending order of destructive influence, can be classified as follows: SN>pink noise>RTN>brown noise.
We analyze the influence of a two-state autocorrelated noise on the decoherence and on the tunnel... more We analyze the influence of a two-state autocorrelated noise on the decoherence and on the tunneling Landau-Zener (LZ) transitions during a two-level crossing of a central electron spin (CES) coupled to a one dimensional anisotropic-antiferomagnetic spin, driven by a time-dependent global external magnetic field. The energy splitting of the coupled spin system is found through an approach that computes the noise-averaged frequency. At low magnetic field intensity, the decoherence (or entangled state) of a coupled spin system is dominated by the noise intensity. The effects of the magnetic field pulse and the spin gap antiferromagnetic material used suggest to us that they may be used as tools for the direct observation of the tunneling splitting through the LZ transitions in the sudden limit. We found that the dynamical frequencies display basin-like behavior decay with time, with the birth of entanglement, while the LZ transition probability shows Gaussian shape.
Polaron states in a quasi 1D cylindrical quantum wire with a parabolic confinement potential are ... more Polaron states in a quasi 1D cylindrical quantum wire with a parabolic confinement potential are investigated applying the Feynman variational principle. The effect of the wire radius on the polaron ground state energy level, the mass and the Fröhlich electron-phonon-coupling constant are obtained for the case of a quasi 1D cylindrical quantum wire. The effect of anisotropy of the structure on the polaron ground state energy level and the mass are also investigated. Analytic expressions for the polaron ground state energy level and mass are derived for the case of strong coupling polarons.
Abstract In the present issue, the magnetoelectric effect in a multiferroic antiferromagnetic spi... more Abstract In the present issue, the magnetoelectric effect in a multiferroic antiferromagnetic spin system with the Dzyaloshinskii Moriya interaction is investigated. The Dzyaloshinskii Moriya interaction is assimilated to a local electric polarization coupled to an electric field which is a site-dependent field as well as the applied external magnetic field. By using the spin-wave theory as a diagonalization method and via the partition function, the physical properties of the system such as magnetoelectric polarizability, magnetization, and electric polarization are obtained. The numerical results reveal that the site-dependent magnetic and electric fields play a remarkable role in the quantum phase transition phenomena that occur in our system. In fact, the magnetoelectric properties response of the system due to the change of the temperature or the external fields reveals the formation of the intermediate states tuneable by the site-dependent parameters. Furthermore, the electric polarization and the magnetoelectric polarizability response of the system due to the variation of the magnetic field show that the magnetoelectric effect can be control by varying the magnetic or/and the electric site-dependent parameter. Overall, the cumulative influence of the site-dependent magnetic and electric fields is a good strategy to detect, elucidate, and control the unconventional phases transition that undergoes a multiferroic antiferromagnetic quantum spin system. Moreover, the results obtained in this work are very interesting for the technological application point of view because there could provide a new prescription for the construction of multifunctional spintronic devices.
We have investigated the dynamic of cooled and trapped polariton state using Landau–Zener–Stuckel... more We have investigated the dynamic of cooled and trapped polariton state using Landau–Zener–Stuckelberg interferometry theory (LZSIT). The effects of exciton–cavity coupling and the laser cooling over the qubit dynamics are analyzed in multi-crossing scenarios, supporting some of our basic results (Kenfack et al. in Comput Condens Matter 11:47–54, 2017; Ekengoue et al. in Comput Condens Matter 14:106–113, 2018). We have performed detailed calculations of the energy eigenvalues, non-adiabatic and adiabatic transition probabilities in the framework of weak- and strong-coupling regime under the laser light. As a main result, we pointed out the braking down of the Pauli exclusion principle providing the applicability of LZSIT for the analysis of polariton’s dynamic through a model which satisfies Fermi–Dirac statistics. Moreover, we found the generation of arbitrary waveforms of interferometric signals including sinusoidal, for weak coupling and strong laser amplitude. Thus, the dynamics of the polariton induces the destruction and the construction of interferences patterns in strong coupling between cavity laser and qubit. Extremely accurate interferometric signals generation by means of geometric phase effect has been demonstrated in this work with the goal of realizing robust control of the quantum coherent states of the polaritonic system. This geometric phase enhancement, which is essentially originated from the dynamic behavior of cooled and trapped polariton, is a significant consequence of the fastest population transfer and quantized energy of the system. Therefore, the geometric phase plays a crucial role in the study of the alter crossings behavior through cooled and trapped polariton, especially in the population transfer and energy of the system.
International Journal of Theoretical Physics, 2019
This paper investigates the time behavior of entanglement (quantified by negativity) and the symm... more This paper investigates the time behavior of entanglement (quantified by negativity) and the symmetry breaking in a symmetric four-qubit system (initialized either in the GHZ-type or W-type states), interacting with a Markov and non-Markov random telegraph noise (RTN). Two different qubit-noise coupling configurations, namely C1 and C2 are investigated. In the first one (C1) it is assumed that, three of the qubits interact with the noise in a common environment (CE) and the remaining qubit in its own local environment while in the second one (C2) it is rather assumed that two of them interact in a CE and the rest also in their own CE. Using the entanglement between the different non-equivalent bipartitions of the qubits (obtained by dividing the system into two arbitrary blocks) as probe, it is demonstrated that the breaking of symmetry in the initialized state of the qubits occurs due to bipartitions of system in which none of the qubit(s) in the right block/partition share the same environment with the remaining qubit(s) in the left block/partition. On the other hand, it is shown that the CE induces an indirect interaction between the qubits which plays a constructive role in reducing the decay rate of entanglement. As a matter of fact, it is shown that the higher the number of qubit interacting in a CE, the more protected the entanglement of the overall system, demonstrating that the C1 scheme is more efficient for shield the system from the detrimental impacts induced by the RTN than the C2 one. Finally, it is shown that strong qubit-environment coupling strength also favors the exchanges of information between the qubits and the external environment.
We investigate in detail the dynamics of decoherence, free and bound entanglements, and the conve... more We investigate in detail the dynamics of decoherence, free and bound entanglements, and the conversion from one to another (quantum state transitions), in a two non-interacting qutrits system initially entangled and subject to independents or a common classical noise. Both Markovian and non-Markovian environments are considered. Furthermore, isotropic and bound entangled states for qutrits systems are considered as initial states. We show the efficiency of the formers over the latters against decoherence, and in preserving quantum entanglement. The loss of coherence increases monotonically with time up to a saturation value depending upon the initial state parameter and is stronger in a collective Markov environment. For the non-Markov regime the presence or absence of entanglement revival and entanglement sudden death phenomena is deduced depending on both the peculiar characteristics of the noise, the physical setup and the initial state of the system. We demonstrate distillability sudden death for conveniently selected parameters in bound entangled states; meanwhile, it is completely absent for isotropic states, where entanglement sudden death is avoided for dynamic noise independently of the noise regime and the physical setup. Our results indicate that distillability sudden death under the Markov/non-Markov noise considered can be avoided depending upon the physical setup.
We provide a detailed analysis of the dynamics of entanglement and quantum correlations for onepa... more We provide a detailed analysis of the dynamics of entanglement and quantum correlations for oneparameter qubit-qutrit states under independent or common classical noises influence. Namely the static noise, the Ornstein-Uhlenbeck (OU) noise and the random telegraph noise. Independently of the intrinsic features of the noises, entanglement measured by negativity and quantum correlations measured by measured-induced disturbance (MID) vanish after a finite time under the effects of independent noise environments. In a common environment setup, we show the existence of specific and very important features of perfect insulation of the systems quantum properties from noise effects, for suitable range of the entanglement parameter. We refer these phenomena to as frozen entanglement and frozen quantum correlations. The dichotomy between entanglement (separability) and quantum correlations is strengthened by our results, with the robustness of MID over entanglement and existence of separable qubit-qutrit states with non-zero quantum correlations.
HAL is a multidisciplinary open access archive for the deposit and dissemination of scientific re... more HAL is a multidisciplinary open access archive for the deposit and dissemination of scientific research documents, whether they are published or not. The documents may come from teaching and research institutions in France or abroad, or from public or private research centers. L'archive ouverte pluridisciplinaire HAL, est destinée au dépôt et à la diffusion de documents scientifiques de niveau recherche, publiés ou non, émanant des établissements d'enseignement et de recherche français ou étrangers, des laboratoires publics ou privés.
International Journal of Quantum Information, 2017
In the present paper, the joint effects of two kinds of classical environmental noises, without d... more In the present paper, the joint effects of two kinds of classical environmental noises, without direct interaction among each other, on the dynamics of quantum correlations (QCs) of a three-qubit system coupled in independent environments is investigated. More precisely, we join the random telegraph noise (RTN) and the static noise (SN) and focus on the dynamics of entanglement and quantum discord (QD) when the qubits are initially prepared in the GHZ- and W-type states. The overall noise affecting the qubits is obtained by combining the RTN and SN in two different setups. The results show that the disorder of the environmental noise as well as its memory qualities and the purity of the initial state considered play a crucial role in the time evolution of the system in such a way that the dynamics of QCs can be controlled by varying them. In fact, we show that, depending on the initial state and noise regime considered, the rate of collapse of QCs may either decrease or increase wit...
Abstract.We address the dynamics of quantum correlations, including entanglement and quantum disc... more Abstract.We address the dynamics of quantum correlations, including entanglement and quantum discord of a three-qubit system interacting with a classical pure dephasing random telegraph noise (RTN) in three different physical environmental situations (independent, mixed and common environments). Two initial entangled states of the system are examined, namely the Greenberger-Horne-Zeilinger (GHZ)- and Werner (W)-type states. The classical noise is introduced as a stochastic process affecting the energy splitting of the qubits. With the help of suitable measures of tripartite entanglement (entanglement witnesses and lower bound of concurrence) and quantum discord (global quantum discord and quantum dissension), we show that the evolution of quantum correlations is not only affected by the type of the system-environment interaction but also by the input configuration of the qubits and the memory properties of the environmental noise. Indeed, depending on the memory properties of the environmental noise and the initial state considered, we find that independent, common and mixed environments can play opposite roles in preserving quantum correlations, and that the sudden death and revival phenomena or the survival of quantum correlations may occur. On the other hand, we also show that the W-type state has strong dynamics under this noise than the GHZ-type ones.
We address the entanglement dynamics of a three-qubit system interacting with a classical fluctua... more We address the entanglement dynamics of a three-qubit system interacting with a classical fluctuating environment described either by a Gaussian or non-Gaussian noise in three different configurations namely: common, independent and mixed environments. Specifically, we focus on the Ornstein-Uhlenbeck (OU) noise and the random telegraph noise (RTN). The qubits are prepared in a state composed of a Greenberger-Horne-Zeilinger (GHZ) and a W state. With the help of the tripartite negativity, we show that the entanglement evolution is not only affected by the type of system-environment coupling but also by the kind and the memory properties of the considered noise. We also compared the dynamics induced by the two kinds of noise and we find that even if both noises have a Lorentzian spectrum, the effects of the OU noise cannot be in a simple way deduced from those of the RTN and vice-versa. In addition, we show that the entanglement can be indefinitely preserved when the qubits are coupled to the environmental noise in a common environment (CE). Finally, the presence or absence of peculiar phenomena such as entanglement revivals (ER) and entanglement sudden death (ESD) is observed.
Abstract.We address the dynamics of decoherence and quantum correlations (entanglement and discor... more Abstract.We address the dynamics of decoherence and quantum correlations (entanglement and discord) in a model of three non-interacting qubits, initially prepared in a maximally entangled pure Greenberger-Horne-Zeilinger (GHZ) state and then subjected to classical environmental noise in common, different and mixed environments. The noise is modeled by randomizing the single-qubit transition amplitudes. We address both static and colored environmental noise. We find that the dynamics of quantum correlations are strongly affected by the type of system-environment interaction and the kind of the noise considered. On the one hand, our results clearly show that unlike what was found in the case of the two-qubit model analogous to the one here investigated, quantum correlations are not totally destroyed when the qubits are coupled to the noise in a common environment. On the other hand, the presence or absence of peculiar phenomena, such as entanglement, revivals and sudden death are observed. Furthermore, we show that the partial preservation of entanglement can be successfully detected by means of the suitable entanglement witness. Finally, in the case of static noise we find that the decoherence becomes stronger as the disorder of the environment increases whereas, for colored noise, it becomes stronger as the number of fluctuators increases.
Abstract In this paper, we examine the time evolution of the quantum mechanical state of a magnet... more Abstract In this paper, we examine the time evolution of the quantum mechanical state of a magnetopolaron using the Pekar type variational method on the electric-LO-phonon strong coupling in a triangular quantum dot with Coulomb impurity. We obtain the Eigen energies and the Eigen functions of the ground state and the first excited state, respectively. This system in a quantum dot is treated as a two-level quantum system qubit and numerical calculations are done. The Shannon entropy and the expressions relating the period of oscillation and the electron-LO-phonon coupling strength, the Coulomb binding parameter and the polar angle are derived.
This paper investigates the evolution and protection of quantum correlations (entanglement and qu... more This paper investigates the evolution and protection of quantum correlations (entanglement and quantum discord (QD) in particular), in a hybrid system formed by a qubit subjected to an external random field and a qutrit subjected to a colored noise generated either by a single or collection of many random bistable fluctuators (RBFs). Two different input states namely the one-and two-parameter class of states of qubitqutrit are investigated. Entanglement and QD are quantified by means of negativity and geometric QD and their protection investigated by recourse to the weak measurement (WM) and weak measurement reversal (WMR) technique. It is shown that the immunity of entanglement and QD against decoherence can be efficiently increased by properly adjusting the parameters of the input states, no matter the spectrum of the colored noise and the number of RBFs considered. Moreover, it is shown that the WM and WMR technique fails in protecting entanglement in the studied system, but can effectively protect QD from the detrimental impacts of the decoherence. In fact, it is shown that performing a WM followed by a WMR on the qubit of the system allows to shield the QD of the system from decoherence even when the decoherence process is strengthen by considering a large number of RBFs affecting the qutrit.
International Journal of Theoretical Physics, 2019
We use a system of three non-interacting qubits as a quantum probe to classify three classical no... more We use a system of three non-interacting qubits as a quantum probe to classify three classical non-Gaussian noises (namely the static, colored (pink and brown) and random telegraph noise), according to their detrimental effects on the evolution of entanglement of the latter. The probe system is initially prepared in the GHZ state and coupled to the noises in independent environments. Seven configurations for the qubit-noise coupling (QNC) are considered. To estimate the destructive influence of each kind of noise, we employ the tripartite negativity to compare the evolution of entanglement in these QNC configurations to each other with the same noise parameters. The results show that the evolution of entanglement is drastically impacted by the QNC configuration considered as well as the properties of the environmental noises and that the SN is more detrimental to the survival of entanglement than the RTN and CN, regardless of the Markov or non-Markov character of the RTN and the color of the CN. We also observed that pink noise is more fatal to the system than the RTN and that the situation is totally reversed in the case of brown noise. Finally, we show that these noises, in descending order of destructive influence, can be classified as follows: SN>pink noise>RTN>brown noise.
We analyze the influence of a two-state autocorrelated noise on the decoherence and on the tunnel... more We analyze the influence of a two-state autocorrelated noise on the decoherence and on the tunneling Landau-Zener (LZ) transitions during a two-level crossing of a central electron spin (CES) coupled to a one dimensional anisotropic-antiferomagnetic spin, driven by a time-dependent global external magnetic field. The energy splitting of the coupled spin system is found through an approach that computes the noise-averaged frequency. At low magnetic field intensity, the decoherence (or entangled state) of a coupled spin system is dominated by the noise intensity. The effects of the magnetic field pulse and the spin gap antiferromagnetic material used suggest to us that they may be used as tools for the direct observation of the tunneling splitting through the LZ transitions in the sudden limit. We found that the dynamical frequencies display basin-like behavior decay with time, with the birth of entanglement, while the LZ transition probability shows Gaussian shape.
Polaron states in a quasi 1D cylindrical quantum wire with a parabolic confinement potential are ... more Polaron states in a quasi 1D cylindrical quantum wire with a parabolic confinement potential are investigated applying the Feynman variational principle. The effect of the wire radius on the polaron ground state energy level, the mass and the Fröhlich electron-phonon-coupling constant are obtained for the case of a quasi 1D cylindrical quantum wire. The effect of anisotropy of the structure on the polaron ground state energy level and the mass are also investigated. Analytic expressions for the polaron ground state energy level and mass are derived for the case of strong coupling polarons.
Abstract In the present issue, the magnetoelectric effect in a multiferroic antiferromagnetic spi... more Abstract In the present issue, the magnetoelectric effect in a multiferroic antiferromagnetic spin system with the Dzyaloshinskii Moriya interaction is investigated. The Dzyaloshinskii Moriya interaction is assimilated to a local electric polarization coupled to an electric field which is a site-dependent field as well as the applied external magnetic field. By using the spin-wave theory as a diagonalization method and via the partition function, the physical properties of the system such as magnetoelectric polarizability, magnetization, and electric polarization are obtained. The numerical results reveal that the site-dependent magnetic and electric fields play a remarkable role in the quantum phase transition phenomena that occur in our system. In fact, the magnetoelectric properties response of the system due to the change of the temperature or the external fields reveals the formation of the intermediate states tuneable by the site-dependent parameters. Furthermore, the electric polarization and the magnetoelectric polarizability response of the system due to the variation of the magnetic field show that the magnetoelectric effect can be control by varying the magnetic or/and the electric site-dependent parameter. Overall, the cumulative influence of the site-dependent magnetic and electric fields is a good strategy to detect, elucidate, and control the unconventional phases transition that undergoes a multiferroic antiferromagnetic quantum spin system. Moreover, the results obtained in this work are very interesting for the technological application point of view because there could provide a new prescription for the construction of multifunctional spintronic devices.
We have investigated the dynamic of cooled and trapped polariton state using Landau–Zener–Stuckel... more We have investigated the dynamic of cooled and trapped polariton state using Landau–Zener–Stuckelberg interferometry theory (LZSIT). The effects of exciton–cavity coupling and the laser cooling over the qubit dynamics are analyzed in multi-crossing scenarios, supporting some of our basic results (Kenfack et al. in Comput Condens Matter 11:47–54, 2017; Ekengoue et al. in Comput Condens Matter 14:106–113, 2018). We have performed detailed calculations of the energy eigenvalues, non-adiabatic and adiabatic transition probabilities in the framework of weak- and strong-coupling regime under the laser light. As a main result, we pointed out the braking down of the Pauli exclusion principle providing the applicability of LZSIT for the analysis of polariton’s dynamic through a model which satisfies Fermi–Dirac statistics. Moreover, we found the generation of arbitrary waveforms of interferometric signals including sinusoidal, for weak coupling and strong laser amplitude. Thus, the dynamics of the polariton induces the destruction and the construction of interferences patterns in strong coupling between cavity laser and qubit. Extremely accurate interferometric signals generation by means of geometric phase effect has been demonstrated in this work with the goal of realizing robust control of the quantum coherent states of the polaritonic system. This geometric phase enhancement, which is essentially originated from the dynamic behavior of cooled and trapped polariton, is a significant consequence of the fastest population transfer and quantized energy of the system. Therefore, the geometric phase plays a crucial role in the study of the alter crossings behavior through cooled and trapped polariton, especially in the population transfer and energy of the system.
International Journal of Theoretical Physics, 2019
This paper investigates the time behavior of entanglement (quantified by negativity) and the symm... more This paper investigates the time behavior of entanglement (quantified by negativity) and the symmetry breaking in a symmetric four-qubit system (initialized either in the GHZ-type or W-type states), interacting with a Markov and non-Markov random telegraph noise (RTN). Two different qubit-noise coupling configurations, namely C1 and C2 are investigated. In the first one (C1) it is assumed that, three of the qubits interact with the noise in a common environment (CE) and the remaining qubit in its own local environment while in the second one (C2) it is rather assumed that two of them interact in a CE and the rest also in their own CE. Using the entanglement between the different non-equivalent bipartitions of the qubits (obtained by dividing the system into two arbitrary blocks) as probe, it is demonstrated that the breaking of symmetry in the initialized state of the qubits occurs due to bipartitions of system in which none of the qubit(s) in the right block/partition share the same environment with the remaining qubit(s) in the left block/partition. On the other hand, it is shown that the CE induces an indirect interaction between the qubits which plays a constructive role in reducing the decay rate of entanglement. As a matter of fact, it is shown that the higher the number of qubit interacting in a CE, the more protected the entanglement of the overall system, demonstrating that the C1 scheme is more efficient for shield the system from the detrimental impacts induced by the RTN than the C2 one. Finally, it is shown that strong qubit-environment coupling strength also favors the exchanges of information between the qubits and the external environment.
We investigate in detail the dynamics of decoherence, free and bound entanglements, and the conve... more We investigate in detail the dynamics of decoherence, free and bound entanglements, and the conversion from one to another (quantum state transitions), in a two non-interacting qutrits system initially entangled and subject to independents or a common classical noise. Both Markovian and non-Markovian environments are considered. Furthermore, isotropic and bound entangled states for qutrits systems are considered as initial states. We show the efficiency of the formers over the latters against decoherence, and in preserving quantum entanglement. The loss of coherence increases monotonically with time up to a saturation value depending upon the initial state parameter and is stronger in a collective Markov environment. For the non-Markov regime the presence or absence of entanglement revival and entanglement sudden death phenomena is deduced depending on both the peculiar characteristics of the noise, the physical setup and the initial state of the system. We demonstrate distillability sudden death for conveniently selected parameters in bound entangled states; meanwhile, it is completely absent for isotropic states, where entanglement sudden death is avoided for dynamic noise independently of the noise regime and the physical setup. Our results indicate that distillability sudden death under the Markov/non-Markov noise considered can be avoided depending upon the physical setup.
We provide a detailed analysis of the dynamics of entanglement and quantum correlations for onepa... more We provide a detailed analysis of the dynamics of entanglement and quantum correlations for oneparameter qubit-qutrit states under independent or common classical noises influence. Namely the static noise, the Ornstein-Uhlenbeck (OU) noise and the random telegraph noise. Independently of the intrinsic features of the noises, entanglement measured by negativity and quantum correlations measured by measured-induced disturbance (MID) vanish after a finite time under the effects of independent noise environments. In a common environment setup, we show the existence of specific and very important features of perfect insulation of the systems quantum properties from noise effects, for suitable range of the entanglement parameter. We refer these phenomena to as frozen entanglement and frozen quantum correlations. The dichotomy between entanglement (separability) and quantum correlations is strengthened by our results, with the robustness of MID over entanglement and existence of separable qubit-qutrit states with non-zero quantum correlations.
HAL is a multidisciplinary open access archive for the deposit and dissemination of scientific re... more HAL is a multidisciplinary open access archive for the deposit and dissemination of scientific research documents, whether they are published or not. The documents may come from teaching and research institutions in France or abroad, or from public or private research centers. L'archive ouverte pluridisciplinaire HAL, est destinée au dépôt et à la diffusion de documents scientifiques de niveau recherche, publiés ou non, émanant des établissements d'enseignement et de recherche français ou étrangers, des laboratoires publics ou privés.
International Journal of Quantum Information, 2017
In the present paper, the joint effects of two kinds of classical environmental noises, without d... more In the present paper, the joint effects of two kinds of classical environmental noises, without direct interaction among each other, on the dynamics of quantum correlations (QCs) of a three-qubit system coupled in independent environments is investigated. More precisely, we join the random telegraph noise (RTN) and the static noise (SN) and focus on the dynamics of entanglement and quantum discord (QD) when the qubits are initially prepared in the GHZ- and W-type states. The overall noise affecting the qubits is obtained by combining the RTN and SN in two different setups. The results show that the disorder of the environmental noise as well as its memory qualities and the purity of the initial state considered play a crucial role in the time evolution of the system in such a way that the dynamics of QCs can be controlled by varying them. In fact, we show that, depending on the initial state and noise regime considered, the rate of collapse of QCs may either decrease or increase wit...
Abstract.We address the dynamics of quantum correlations, including entanglement and quantum disc... more Abstract.We address the dynamics of quantum correlations, including entanglement and quantum discord of a three-qubit system interacting with a classical pure dephasing random telegraph noise (RTN) in three different physical environmental situations (independent, mixed and common environments). Two initial entangled states of the system are examined, namely the Greenberger-Horne-Zeilinger (GHZ)- and Werner (W)-type states. The classical noise is introduced as a stochastic process affecting the energy splitting of the qubits. With the help of suitable measures of tripartite entanglement (entanglement witnesses and lower bound of concurrence) and quantum discord (global quantum discord and quantum dissension), we show that the evolution of quantum correlations is not only affected by the type of the system-environment interaction but also by the input configuration of the qubits and the memory properties of the environmental noise. Indeed, depending on the memory properties of the environmental noise and the initial state considered, we find that independent, common and mixed environments can play opposite roles in preserving quantum correlations, and that the sudden death and revival phenomena or the survival of quantum correlations may occur. On the other hand, we also show that the W-type state has strong dynamics under this noise than the GHZ-type ones.
We address the entanglement dynamics of a three-qubit system interacting with a classical fluctua... more We address the entanglement dynamics of a three-qubit system interacting with a classical fluctuating environment described either by a Gaussian or non-Gaussian noise in three different configurations namely: common, independent and mixed environments. Specifically, we focus on the Ornstein-Uhlenbeck (OU) noise and the random telegraph noise (RTN). The qubits are prepared in a state composed of a Greenberger-Horne-Zeilinger (GHZ) and a W state. With the help of the tripartite negativity, we show that the entanglement evolution is not only affected by the type of system-environment coupling but also by the kind and the memory properties of the considered noise. We also compared the dynamics induced by the two kinds of noise and we find that even if both noises have a Lorentzian spectrum, the effects of the OU noise cannot be in a simple way deduced from those of the RTN and vice-versa. In addition, we show that the entanglement can be indefinitely preserved when the qubits are coupled to the environmental noise in a common environment (CE). Finally, the presence or absence of peculiar phenomena such as entanglement revivals (ER) and entanglement sudden death (ESD) is observed.
Abstract.We address the dynamics of decoherence and quantum correlations (entanglement and discor... more Abstract.We address the dynamics of decoherence and quantum correlations (entanglement and discord) in a model of three non-interacting qubits, initially prepared in a maximally entangled pure Greenberger-Horne-Zeilinger (GHZ) state and then subjected to classical environmental noise in common, different and mixed environments. The noise is modeled by randomizing the single-qubit transition amplitudes. We address both static and colored environmental noise. We find that the dynamics of quantum correlations are strongly affected by the type of system-environment interaction and the kind of the noise considered. On the one hand, our results clearly show that unlike what was found in the case of the two-qubit model analogous to the one here investigated, quantum correlations are not totally destroyed when the qubits are coupled to the noise in a common environment. On the other hand, the presence or absence of peculiar phenomena, such as entanglement, revivals and sudden death are observed. Furthermore, we show that the partial preservation of entanglement can be successfully detected by means of the suitable entanglement witness. Finally, in the case of static noise we find that the decoherence becomes stronger as the disorder of the environment increases whereas, for colored noise, it becomes stronger as the number of fluctuators increases.
Abstract In this paper, we examine the time evolution of the quantum mechanical state of a magnet... more Abstract In this paper, we examine the time evolution of the quantum mechanical state of a magnetopolaron using the Pekar type variational method on the electric-LO-phonon strong coupling in a triangular quantum dot with Coulomb impurity. We obtain the Eigen energies and the Eigen functions of the ground state and the first excited state, respectively. This system in a quantum dot is treated as a two-level quantum system qubit and numerical calculations are done. The Shannon entropy and the expressions relating the period of oscillation and the electron-LO-phonon coupling strength, the Coulomb binding parameter and the polar angle are derived.
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Papers by Cornelius Fai