Intrinsic Decoherence Research Articles

Skew information correlations beyond entanglement in dissipative two Su(2)-systems

We investigate the dynamics of quantum correlations [including skew information correlations beyond entanglement] of two isolated Su(2)-systems that are initially in a maximum Bell state or in a separable state. Each Su(2)-system is interacting with two-mode Su(1,1) coherent states. The time evolution of the density matrix of the two Su(2)-systems with the effect of intrinsic decoherence is analytically explored. The robustness of the initial quantum correlations for several initial coherence intensities, detunings, and intrinsic decoherences, is investigated. The robustness analysis of various correlation functions is based on the concurrence and quantum skew information. It is shown that the phenomena of sudden death and birth entanglement, and the sudden changes of local quantum uncertainty can be controlled. The correlations of the skew information present good robustness against the intrinsic decoherence and the detuning.

Quantum Correlation and Coherence in Dissipative Two SC-Qubit Systems Interacting with a Coherent SC-Cavity

An analytical solution of the master equation is obtained for a coherent SC-cavity interacts with two SC-qubits. With this solution, the effect of an intrinsic decoherence on the growth of coherence loss (mixture) and the entanglement degradation is shown. Due to the intrinsic decoherence, the oscillatory behavior of the qubit-inversion is deteriorated, and its amplitude decreases. Where its stationary state refers to that the energy is stored more in the SC-qubits. The growth of the mixture is investigated for the entire system and its sub-systems of the SC-cavity and two qubits. The entanglement is studied for two different partitions, between the SC-cavity and the two qubits as well as between the two qubits. It is found that the generation of the entanglement and mixture and their stationary values depend on the initial coherence intensity and the intrinsic decoherence rate. The stationary entanglement and mixture, and the phenomena of sudden appearance and disappearance of the entanglement could be controlled by adjusting the intrinsic noise rate and the initial coherence intensity.

Enhancing the Generated Stable Correlation in a Dissipative System of Two Coupled Qubits inside a Coherent Cavity via Their Dipole-Dipole Interplay.

We explore the dissipative dynamics of two coupled qubits placed inside a coherent cavity-field under dipole-dipole interplay and 2-photon transitions. The generated non-classical correlations (NCCs) beyond entanglement are investigated via two measures based on the Hilbert-Schmidt norm. It is found that the robustness of the generated NCCs can be greatly enhanced by performing the intrinsic dissipation rate, dipole-dipole interplay rate, initial coherence intensity and the degree of the coherent state superpositions. The results show that the intrinsic decoherence stabilize the stationarity of the non-classical correlations while the dipole interplay rate boost them. The non-classical correlations can be frozen at their stationary correlations by increasing the intrinsic dissipation rate. Also NCCs, can be enhanced by increasing the initial coherent intensity.

Remote Hamiltonian interactions mediated by light

We address a fundamental question of quantum optics: Can a beam of light mediate coherent Hamiltonian interactions between two distant quantum systems? This is an intriguing question whose answer is not a priori clear, since the light carries away information about the systems and might be subject to losses, giving rise to intrinsic decoherence channels associated with the coupling. Our answer is affirmative and we derive a particularly simple sufficient condition for the interactions to be Hamiltonian: The light field needs to interact twice with the systems and the second interaction has to be the time reversal of the first. We demonstrate that, even in the presence of significant optical loss, coherent interactions can be realized and generate substantial amounts of entanglement between the systems. Our method is directly applicable for building hybrid quantum systems, with relevant applications in the fields of optomechanics and atomic ensembles.

Quantum Fisher Information and Entanglement of Moving Two Two-Level Atoms under the Influence of Environmental Effects

We have investigated numerically the dynamics of quantum Fisher information (QFI) and quantum entanglement (QE) of a two moving two-level atomic systems interacting with a coherent and thermal field in the presence of intrinsic decoherence (ID) and Kerr (non-linear medium) and Stark effects. The state of the entire system interacting with coherent and thermal fields is evaluated numerically under the influence of ID and Kerr (nonlinear) and Stark effects. QFI and von Neumann entropy (VNE) decrease in the presence of ID when the atomic motion is neglected. QFI and QE show an opposite response during its time evolution in the presence of a thermal environment. QFI is found to be more susceptible to ID as compared to QE in the presence of a thermal environment. The decay of QE is further damped at greater time-scales, which confirms the fact that ID heavily influences the system’s dynamics in a thermal environment. However, a periodic behavior of entanglement is observed due to atomic motion, which becomes modest under environmental effects. It is found that a non-linear Kerr medium has a prominent effect on the VNE but not on the QFI. Furthermore, it has been observed that QFI and QE decay soon under the influence of the Stark effect in the absence of atomic motion. The periodic response of QFI and VNE is observed for both the non-linear Kerr medium and the Stark effect in the presence of atomic motion. It is observed that the Stark, Kerr, ID, and thermal environment have significant effects during the time evolution of the quantum system.

Thermal Field and Intrinsic Decoherence Effects on the Dynamics of N-level Moving Atomic System

Dynamical behaviour of Quantum Entanglement (QE) and atomic Quantum Fisher Information (AQFI) for a moving N-level atomic system is studied in a thermal environment. Time evolution of state vector of the entire system interacting with thermal field is calculated numerically in the presence of intrinsic decoherence. It is observed that intrinsic decoherence and thermal environment play dominant role during the time evolution of the quantum system. AQFI and entanglement show an opposite behaviour during its time evolution in the presence of thermal environment. AQFI is observed to be more prone to intrinsic decoherence as compared to the entanglement in a thermal environment. AQFI is found to be more prone to intrinsic decoherence as compared to the QE in a thermal environment. QE is found decaying when the parameter of intrinsic decoherence is increased in the absence of atomic motion. The damping behaviour of QE is observed for longer time-scales. The periodic response of entanglement due to atomic motion becomes moderate under the influence of these environments. The intrinsic decoherence and thermal environment are found to suppress the nonclassical effects of the quantum system. QE and AQFI saturate to a lower level for larger time-scales under the influence of these environments. Furthermore, the dynamics of AQFI and von Neumann entropy (VNE) changes remarkably by changing the mean number of photons.

Effect of intrinsic decoherence on entanglement of three polar molecules with two-dimensional rotation

The dynamic entanglement of three polar molecules with two-dimensional rotations is investigated under the influence of an electric field and intrinsic decoherence. The parameters of the electric field, such as strength and orientation, are tuned to tailor the rotational properties of the molecules. Due to the two-dimensional rotation and its dipole–dipole interaction, a mechanism of two-molecule transition occurs and leads to specific quantum states in the tripartite system. The components of the states are analyzed by varying the symmetry of the molecular arrangement. We evaluate the negativity to probe the entanglement characteristics of the system. The negativity shows distinct oscillating features for initial GHZ, W, and inverted-W states. These features are suppressed and eventually smoothed in the presence of intrinsic decoherence. We further analyze the contribution of the quantum states to the entanglement. Due to specific selection rules, only two of the states are found to dominate the evolution of the negativity. Among the three cases, the system based on the inverted-W state evolves with the lowest loss of entanglement.

Influence of Magnetic Field on Qutrit Teleportation under Intrinsic Decoherence

We study qutrit teleportation through a qutrit xyz chain, in the presence of intrinsic decoherence and a non-homogeneous magnetic field. We study the effects of intrinsic phase change, magnetic field and entanglement of the initial state of the channel. It is observed that while the intrinsic phase change and the non-homogeneity of the magnetic field have adverse effects on the teleportation fidelity, the entanglement of the initial state of the channeled enhances the latter. Moreover, the intrinsic decoherence may remove the ripples from the time curve that is delivered by the Schrodinger channel.

Quantum-memory-assisted entropic uncertainty in two-qubit Heisenberg XYZ chain with Dzyaloshinskii–Moriya interactions and effects of intrinsic decoherence

Quantum-memory-assisted entropic uncertainty relation (QMA-EUR) in two-qubit Heisenberg XYZ spin chain model with Dzyaloshinskii–Moriya (DM) interaction has been investigated. The paper shows that the DM interactions and the spin interactions alone x, y, z directions can efficiently suppress the entropic uncertainty of Pauli observables ( $$\sigma _{x}$$ and $$\sigma _{z}$$ ), even make the entropic uncertainty close to zero. As well, it is pointed out that the entropic uncertainty reaches to zero at very low temperature, starts to increase with temperature after a threshold, and generally becomes constant at a fixed value. We also verified the Bob’s uncertainty about Alice’s measurement outcomes is anticorrelated with the sum of the accessible information of observer. Furthermore, the decoherence conditions including dephasing and noisy environments are considered. For the fixed initial state, the entropic uncertainty of the XYZ model with DM interaction in z-direction are independent of spin–spin coupling $$J_z$$ and the anisotropy parameter $$\varDelta $$ . In the dephasing environment, the evolutions of entropic uncertainty and its lower bound $$U_{B}$$ oscillate with the time and saturates at a finite value, and this value is varied with the purity parameter r of initial state. In the noisy environment, the entropic uncertainty and its lower bound monotonically increase with the time and will be stable at value 2 quickly. This is because the combined effects of the DM interaction and the decoherence force the various initial entanglement states to oscillate into an identical state, regardless of the value of $$D_{z}$$ and the parameter r of initial state.

Taming electronic decoherence in one-dimensional chiral ballistic quantum conductors

Although interesting per se, decoherence and relaxation of single-electron excitations induced by strong effective screened Coulomb interactions in Quantum Hall edge channels are an important challenge for the applications of electron quantum optics in quantum information and quantum sensing. In this paper, we study intrinsic single-electron decoherence within an ideal single-electron channel with long-range effective Coulomb interactions to determine the influence of the material and sample properties. We find that weak-coupling materials characterized by a high velocity of hot-electron excitations may offer interesting perspectives for limiting intrinsic decoherence due to electron/electron interactions. We discuss quantitively how extrinsic decoherence due to the coupling with the channel's electromagnetic environment can be efficiently inhibited in specially designed samples at $\nu=2$ with one closed edge channel and we propose a realistic geometry for testing decoherence control in an Hong Ou Mandel experiment.

Application quantum renormalization group to optimal dense coding in transverse Ising model

We have merged the object of renormalization group(RG) with quantum dense coding for one-dimensional Ising model in a transverse field. At first, we have shown how the dynamic quantum discord(QD) evolves in present intrinsic decoherence when the size of the system becomes large, i.e., the finite size scaling is obtained. By considering that the generation of highly entangled quantum states is a fundamental requirement for quantum information, the main purpose of this work is to answer the following question: how the valid optimal dense coding can be determined by RG in many body systems? We find that the optimal dense coding capacity depends on the normalization group. It has been found that valid dense coding can exist with the increasing of RG steps. Moreover, the results show that by increasing of RG steps, valid dense coding capacity suddenly occurs near the critical point of the quantum phase transition in present intrinsic decoherence. Using this approach, identifying a critical point of the transverse Ising model in dense coding capacity quality can be very effective.

Universal evolution of non-classical correlations due to collective spontaneous emission

We explore the spontaneous generation and decay of quantum correlations between two identical atoms coupled to a common Markovian environment in the presence of electromagnetic field modes. For this purpose, we analyze the dynamics of quantum correlations by employing the concurrence, the trace quantum discord and the local quantum uncertainty, for collective Dicke states. It is shown that the collective damping and dipole-dipole interaction plays a key role in enhancing non-classical correlations during the process of intrinsic decoherence. The quantum correlations can be maintained over a long time but for small distance between the two atoms.

Non-classical correlations in two quantum dots coupled in a coherent resonator field under decoherence

An analytical description is obtained for two excitons; each exciton is in one of two distant quantum dots embedded in a nano-mechanical resonator which is initially prepared in a superposition of coherent states with intrinsic decoherence. We use a particular method based on the dressed states of the model Hamiltonian. The robustness of the generated non-classical correlations is investigated via the measurement-induced nonlocality and geometric quantum discord, compared with the log-negativity. The three measures present generated different correlations that depend on the initial coherence states and their intensities, and intrinsic decoherence. It is witnessed that the phenomena of sudden appearance and disappearance of entanglement are occurring and repeated at chosen intervals of time; they can disappear due to the intrinsic decoherence. The correlations were observed to attain highest robustness under initial coherent state, with decoherence parameter. Quantum correlation functions survive in the stationary states, and the amount of stationary correlations could be controlled by adjusting the values of the intrinsic decoherence, the initial state of the nanomechanical resonator and its coherence intensity.

Dynamics of a Moving Two-Level Atom Under the Influence of Intrinsic Decoherence

We present a general and fascinating problem of quantum entanglement (QE) that is calculated with the help of quantum Fisher information (QFI) and von Neumann entropy (VNE) for moving two-level atomic systems. We calculate numerically the temporal evolution of the state vector of the entire system under the influence of intrinsic decoherence for a moving two-level atom. We demonstrate that the phase shifts of an estimator parameter, intrinsic decoherence, and the atomic motion play an important and prominent role during the time evolution of the atomic system. We observe that there is a monotonic relation between the atomic quantum Fisher information (QFI) and quantum entanglement (QE) in the absence of atomic motion. We also show that at the revival time the local maximum values of QFI decreases gradually. A periodic behavior of QFI is observed in the presence of atomic motion, which becomes more important and remarkable for two-level atomic systems. Moreover, the atomic quantum Fisher information and entanglement demonstrate an opposite response during the time evolution in the presence of atomic motion. We show that the evolution of entanglement is more susceptible to the intrinsic decoherence; a considerable change occurs in the degree of entanglement when the intrinsic decoherence parameter increases. Intrinsic decoherence in the atom–field interaction represses the nonclassical effects of the atomic systems. Both the entanglement and the quantum Fisher information saturate to their lower levels for longer time scales in the presence of intrinsic decoherence. For larger values of intrinsic decoherence, the sudden death of entanglement is observed.

Robustness of Quantum Correlations in Entangled Two su(2) Systems Non-mutually Interacting with su(1, 1) System under Intrinsic Decoherence

Two two-level systems generated by su(2) algebra are initially prepared in a maximum nonsymmetric Bell state and having no mutual interaction. Each su(2)-system spatially interacts with two-mode cavity field in the nondegenerate parametric amplifier type cast through operators governed by su(1, 1) Lie algebra. An analytical description for the time evolution of the final state of the total system with the effect of intrinsic decoherence is found. Therefore, the robustness of the quantum correlations between the two su(2)-system is investigated by means of geometric quantum discord, measurement-induced nonlocality and negativity. We analyze in some detail the influence of initial coherence intensities, detuning and phase decoherence parameters on the steady-state correlation. We find that the steady-state correlations can be generated and enhanced by controlling the parameters of: the initial coherence intensities, the Bargmman index and the detuning. It is shown that the phenomenon of sudden death and re-birth of entanglement, and the sudden changes of the geometric quantum correlation can be controlled by these parameters. We find that the robustness of the quantum correlation can be greatly enhanced by the Bargmman index and the resonance detuning. Negativity is the measure most susceptible to phase decoherence, while geometric quantum discord and measurement-induced nonlocality are the more robust measures.

Stationary quantum correlation and coherence of two-mode Kerr nonlinear coupler interdicting with Su(2)-system under intrinsic damping

ABSTRACTA two-level atom interacting with two nonlinear Kerr oscillators pumped by an optical parametric process is studied. An analytical solution for the dynamical evolution of an interaction between Su and Su-systems is derived. The role of intrinsic damping, detuning, and Kerr-like medium on the entanglement evolution, quantum correlation, and coherence is elucidated. It is shown that the intrinsic decoherence leads to the sudden death and sudden birth entanglement, while the detuning eradicates these effects. The quantum coherence growth can be controlled by the detuning and the Kerr-like medium.

Entropy Squeezing of a Qubit Interdicting with Two-Mode Kerr Nonlinear Coupler Due to Intrinsic Damping

An analytical description for the dynamical evolution of a qubit interacting with two nonlinear Kerr oscillators pumped by optical parametric process is derived through Su(1, 1)-algebraic treatment. The role of intrinsic damping, detuning and Kerr-like Medium on the squeezing phenomenon is elucidated via information entropy squeezing. The evolutions of the interaction of the qubit with two-mode Kerr nonlinear coupler lead to the appearance the regular squeezing phenomenon during the chosen time-interval. The preserving and protecting of the qubit components from the squeezing can be controlled by the intrinsic decoherence, detuning and the Kerr-like medium effects. Where the squeezing phenomenon deteriorates with increasing the decoherence rate, whereas, the Kerr-like medium can not protect some qubit components from the squeezing.

Entropic uncertainty relation in a two-qutrit system with external magnetic field and Dzyaloshinskii–Moriya interaction under intrinsic decoherence

In this paper, we explore the dynamic behaviors of entropic uncertainty relation in a two-qutrit system which is in the presence of external magnetic field and Dzyaloshinskii–Moriya (DM) interaction under intrinsic decoherence. The effects of the isotropic bilinear interaction, the external magnetic field, the DM interaction strength, as well as the intrinsic decoherence on the entropic uncertainty relation have been demonstrated in detail. Compared with previous results, our results show that, controlling the isotropic bilinear interaction parameter J, the external magnetic field strength $$B_{0}$$ , the DM interaction parameter D can result in inflation of the uncertainty, while increasing the intrinsic decoherence parameter can lift the uncertainty of the measurement. In particularly, under certain conditions (e.g., parameters J, $$B_{0}$$ and D are large enough), the entropic uncertainty will ultimately tend to a stable value and be immune to decoherence.

Entropic uncertainty relation of a two-qutrit Heisenberg spin model in nonuniform magnetic fields and its dynamics under intrinsic decoherence

The precision of measurements for two incompatible observables in a physical system can be improved with the assistance of quantum memory. In this paper, we investigate the quantum-memory-assisted entropic uncertainty relation for a spin-1 Heisenberg model in the presence of external magnetic fields, the systemic quantum entanglement (characterized by the negativity) is analyzed as contrast. Our results show that for the XY spin chain in thermal equilibrium, the entropic uncertainty can be reduced by reinforcing the coupling between the two particles or decreasing the temperature of the environment. At zero-temperature, the strong magnetic field can result in the growth of the entropic uncertainty. Moreover, in the Ising case, the variation trends of the uncertainty are relied on the choices of anisotropic parameters. Taking the influence of intrinsic decoherence into account, we find that the strong coupling accelerates the inflation of the uncertainty over time, whereas the high magnetic field contributes to its reduction during the temporal evolution. Furthermore, we also verify that the evolution behavior of the entropic uncertainty is roughly anti-correlated with that of the entanglement in the whole dynamical process. Our results could offer new insights into quantum precision measurement for the high spin solid-state systems.

Nonclassical features of two SC-qubit system interacting with a coherent SC-cavity

In this paper, the dynamics of two charged qubits interacting with a coherent SC-cavity in the presence of the intrinsic decoherence is investigated analytically. Some nonclassical features are discussed as: The behavior of the negativity part of the Wigner function, the Husimi function and its marginal distributions. It is shown that, the intrinsic decoherence has a clearly effect on the negative part of the Wigner function, where it does not vanish completely but reach its stationary value as the intrinsic-decoherence rate increases. A definition of the Husimi distribution for the two SC-qubit and its marginal distributions is described. Further, in the presence of the intrinsic decoherence, the dynamics of the Husimi function of the two-qubit is more robust than its marginal distributions. The phase space quantum coherence of the reduced density matrices is investigated via the Wehrl entropies, which are shown loss of the quantum coherence due to the interaction of coherent SC-cavity with the its system. It is found that, the stationary Wehrl entropies appear quicker due to increasing the intrinsic decoherence rate.