arXiv subjects

E. Faizi

Publications and source records attributed to E. Faizi.

13 recordsLinked to original sources

arXiv2018

Requirement of system-reservoir bound states for entanglement protection

In this work, a genuine mechanism of entanglement protection of a two-qubit system interacting with a dissipative common reservoir is investigated. Based on the generating of bound state for the system-reservoir, we show that stronger bound state in the energy spectrum can be created by adding other non-interacting qubits into the reservoir. In the next step, it is found that obtaining higher degrees of boundedness in the energy spectrum leads to better protection of two-qubit entanglement against the dissipative noises. Also, it is figured out that the formation of bound state not only exclusively determines the long time entanglement protection, irrespective to the Markovian and non-Markovian dynamics, but also performs the task for reservoirs with different spectral densities.

quant-ph↗

arXiv2017

Controlling speedup in open quantum systems through the manipulating of system-reservoir bound states

In this paper, we give a mechanism for controlling speedup of a single-qubit open quantum system by exclusively manipulating the system-reservoir bound states using additional non-interacting qubits. It is demonstrated that providing stronger bound states in the system-reservoir spectrum makes the single-qubit evolution with higher speed. We examine the performance of the mechanism for different spectral densities such as Lorentzian and Ohmic and find out the decisive role of bound states manipulation in speeding up of quantum evolution.

quant-ph↗

arXiv2017

Quantum speed limit time for a two-qubit system interacting with independent and common reservoirs

We study the quantum speed limit time for a two-qubit system interacts with indepen- dent and common reservoir. The system is initially prepared in a class of X-structure density matrix, namely the extended Werner-like states (EWL). We demonstrate that when reservoir enters to the non-Markovian regime, the quantum speed limit time de- crease more sharply in a common reservoir than independent reservoirs.

quant-ph↗

arXiv2017

Quantum discord protection of a two-qutrit V-type atomic system from decoherence by partially collapsing measurements

In this paper, by exploiting the weak measurement and quantum measurement re- versal (WMQMR) procedure, we propose a scheme to show how one can protect the geometric quantum discord (GQD) of a two-qutrit V-type atomic system each of which interacts with a dissipative reservoir independently. We examine the scheme for the GQD of the initial two-qutrit Werner and Horodecki states for different classes of weak mea- surement strengthes. It is found out that the presented protocol enables us to suppress decoherence due to the amplitude damping (AD) channel and preserve the quantum dis- cord of the two-qutrit system successfully.

quant-ph↗

arXiv2016

Effect of two-qutrit entanglement on quantum speed limit time of a bipartite V-type open system

In the present paper, quantum speed limit (QSL) time of a bipartite V-type three-level atomic system under the effect of two-qutrit entanglement is investigated. Each party interacts with own independent reservoir. By considering two local unitarily equivalent Wener states and the Horodecki PPT state, as initial states, the QSL time is evaluated for each of them in the respective entangled regions. It is counterintu-itively observe that the effect of entanglement on the QSL time driven from each of the initial Werner states are completely different when the degree of non-Markovianity is considerable. In addition, it is interesting that the effect of entanglement of the non-equivalent Horodecki state on the calculated QSL time displays an intermediate behavior relative to the cases obtained for the Werner states.

quant-ph↗

arXiv2015

Quantum correlations in Ising-XYZ diamond chain structure under an external magnetic field

In this paper, we consider an entangled Ising-XYZ diamond chain structure. Quantum correlations for this model is investigated by using of quantum discord and trace distance discord. Quantum correlations is obtained for different values of the anisotropy parameter, magnetic field and temperature. By comparison between quantum correlations, we show trace distance discord is always larger than quantum discord. Finally, some novel effects, such as increasing the quantum correlations with temperature and constructive role of anisotropy parameter which may paly to the quantum correlations were observed.

quant-ph↗

arXiv2015

Local quantum uncertainty of SU(2) invariant states

In this paper, we investigated quantum correlation in SU (2) invariant quantum spin systems by local quantum uncertainty(LQU). These states are invariant under global rotations of both subsystems and in real physical systems, such states arise from thermal equilibrium states of isotropic spin systems. We derive an analytic expression for the LQU of (2j +1)*2 and (2j +1)*3 quantum spin systems with SU (2) symmetry.

quant-ph↗

arXiv2014

Super quantum discord for a class of two-qubit states with weak measurement

So far, super quantum discord has been calculated explicitly only for Bell-diagonal states and expressions for more general quantum states are not known. In this paper, we derive explicit expressions for super quantum discord for a larger class of two-qubit states, namely, a 4-parameter family of two-qubit states. We observe that, weak measurements obtain more quantumness of correlations than strong measurements. As an application, the dynamic behavior of the super quantum discord under decoherence channel is investigated. We find that, the super quantum discord decreases monotonically as a function of the measurement strength parameter.

quant-ph↗

arXiv2014

Quantum discord and one-norm geometric quantum discord for XXX Heisenberg spin chain under noisy channels

Here, we compare the behavior of the quantum discord, 1-norm geometric quantum discord and concurrence under the effect of decoherence for XXX Heisenberg spin chain. Their dependencies on temperature and coupling constant are presented in detail. By a comparison between them we can see that quantum discord and 1-norm geometric quantum discord are more robust than the concurrence against decoherence in the sense that quantum discord and 1-norm geometric quantum discord takes a nonzero value and decrease asymptotically, while the concurrence is zero in a large range of parameters including temperature and coupling constant. Moreover, we find that there is no simple relative ordering between 1-norm geometric quantum discord and quantum discord. This result contradicts the information which provided in some papers.

quant-ph↗

arXiv2014

Comparison of quantum discord and local quantum uncertainty in a vertical quantum dot

In this paper, we consider quantum correlations (quantum discord and local quantum uncertainty) in a vertical quantum dot. Their dependencies on magnetic field and temperature are presented in detail. It is noticeable that, quantum discord and local quantum uncertainty behavior is similar to a large extent. In addition, the time evolution of quantum discord and local quantum uncertainty under dephasing and amplitude damping channels is investigated. It has been found that, for some Belldiagonal states quantum discord is invariant under some decoherence in a finite time interval [Phys. Rev. Lett. 104, 200401 (2010)]. Also, our results show that quantum discord is invariant under dephasing channel for a finite time interval in a vertical quantum dot, while this phenomenon does not occurs for local quantum uncertainty case.

quant-ph↗

arXiv2014

Investigation of the Quantum Correlations for a S=1/2 Ising- Heisenberg Model on a Symmetrical Diamond Chain

We consider the quantum correlations for a S=1/2 Ising- Heisenberg model of a symmetrical diamond chain. Firstly, we compare concurrence, quantum discord and 1- norm geometric quantum discord of an ideal diamond chain in the absence of magnetic field. The results show no simple ordering relations between these quantum correlations, so that quantum discord may be smaller or larger than the 1-norm geometric quantum discord, which this observation contradict the previous result that provided by F. M. Paula [1]. Symmetrical behavior of quantum correlation versus ferromagnetic and anti- ferromagnetic coupling constant J is considerable. The effect of external magnetic field H and temperature- dependence is also considered. Furthermore, we study quantum discord and geometric measure of quantum discord with the effect of next nearest neighbor interaction between nodal Ising sites for a generalized diamond chain, and we observe coexistence of phases with different values of magnetic field for quantum correlations. Moreover, entanglement sudden death occurs while quantum discord, 1- norm geometric quantum discord and geometric quantum discord are immune from sudden death.

quant-ph↗

arXiv2006

Generic N-coupled maps in Bose-Mesner algebra perspective

By choosing a dynamical system with d different couplings, one can rearrange a system based on the graph with given vertex dependent on the dynamical system elements. The relation between the dynamical elements (coupling) is replaced by a relation between the vertexes. Based on the E_0 transverse projection operator. We addressed synchronization problem of an array of the linearly coupled map lattices of identical discrete time systems. The synchronization rate is determined by the second largest eigenvalue of the transition probability matrix. Algebraic properties of the Bose-Mesner algebra with an associated scheme with definite spectrum has been used in order to study the stability of the coupled map lattice. Associated schemes play a key role and may lead to analytical methods in studying the stability of the dynamical systems. The relation between the coupling parameters and the chaotic region is presented. It is shown that the feasible region is analytically determined by the number of couplings (i.e, by increasing the number of coupled maps the feasible region is restricted). It is very easy to apply our criteria to the system being studied and they encompass a wide range of coupling schemes including most of the popularly used ones in the literature.

nlin.CD↗

arXiv2000

2 and 3-dimensional Hamiltonians with Shape Invariance Symmetry

Via a special dimensional reduction, that is, Fourier transforming over one of the coordinates of Casimir operator of su(2) Lie algebra and 4-oscillator Hamiltonian, we have obtained 2 and 3 dimensional Hamiltonian with shape invariance symmetry. Using this symmetry we have obtained their eigenspectrum. In the mean time we show equivalence of shape invariance symmetry and Lie algebraic symmetry of these Hamiltonians.

math-ph↗