Kinetics of the oxidation of diaqua(nitrilotriacetato)cobaltate(II) in water-ethanol mixtures

Summary The kinetics of the oxidation of diaqua(nitrilotriacetato) cobaltate(II) by periodate have been studied in various ethanol-water mixtures covering the range 0 to 65 wt% ethanol, at seven different temperatures in the range 20–50 °C. The effect of solvent on the rate and mechanism of the reaction has been investigated. An inner-sphere mechanism for the reaction is proposed, a result consistent with the calculated activation parameters.     

Kinetics and mechanism of oxidation of (ethylenediaminediacetato)chromium(III) by N-bromosuccinimide

The kinetics of oxidation of (ethylenediaminediacetato)-chromium(III), [Cr(EDDA)(OH2)2]+, by N-bromosuccinimide (NBS) in aqueous solution to yield CrVI have been studied spectrophotometrically over the 20–40°C range. The reaction rate is first order with respect to both [NBS] and [CrIII], and increases with pH over the range 4.8–5.8. The activation parameters were calculated. A mechanism in which deprotonated [CrIII(EDDA)(OH2)(OH)] is the reactive species is suggested. The electron transfer may proceed via an inner sphere mechanism through bridging of the two reactants by the hydroxo ligand.     

Effect of the time-dependent coupling on a superconducting qubit-field system under decoherence: Entanglement and Wehrl entropy

The dynamics of a superconducting (SC) qubit interacting with a field under decoherence with and without time-dependent coupling effect is analyzed. Quantum features like the collapse–revivals for the dynamics of population inversion, sudden birth and sudden death of entanglement, and statistical properties are investigated under the phase damping effect. Analytic results for certain parametric conditions are obtained. We analyze the influence of decoherence on the negativity and Wehrl entropy for different values of the physical parameters. We also explore an interesting relation between the SC-field entanglement and Wehrl entropy behavior during the time evolution. We show that the amount of SC-field entanglement can be enhanced as the field tends to be more classical. The studied model of SC-field system with the time-dependent coupling has high practical importance due to their experimental accessibility which may open new perspectives in different tasks of quantum formation processing.     

Dephasing Process of a Single Atom Interacting with a Two-Mode Field

We consider the interaction of a qubit system with a two-mode field in the presence of multi-photon transition and phase damping effect. We use the master equation to obtain the density operator when the qubit is initially prepared in its excited state and the field is in a finite-dimensional pair coherent state. The properties of the considered system, such as the population inversion, amount of the mixedness, parameter estimation, and squeezing, are explored for one- and two-photon transitions. The effects of photon addition to the field and phase damping on the evaluation of these quantumness measures are also investigated.     

Dynamics of a moving five-level atom interacting with cavity fields

We study the entanglement between a single five-level atom interacting with a one-mode cavity field in the case where the atomic motion is taken into account. The field entropy of this system is investigated under the nonresonant conditions. The effects of the detuning parameter and the atomic motion on the degree of entanglement are investigated. We show that both the detuning and atomic motion play important roles in the evolution of the von Neumann entropy and atomic populations.     

Fisher information due to a phase noisy laser under non-Markovian environment

More recently, K. Berrada [Annals of Physics 340 (2014) 60-69] [1] studied the geometric phase of a two-level atom system driven by a phase noise laser under non-Markovian dynamics in terms of different parameters involved in the whole system, and collapse and revival phenomena were found for large class of states. In this paper, using this noise effect, we study the quantum fisher information (QFI) for a two-level atom system driven by a phase noise laser under non-Markovian dynamics. A new quantity, called QFI flow is used to characterize the damping effect and unveil a fundamental connection between non-Markovian behavior and dynamics of system–environment correlations under phase noise laser. It is shown that QFI flow has disappeared suddenly followed by a sudden birth depending on the kind of the environment damping. QFI flow provides an indicator to characterize the dissipative quantum system’s decoherence by analyzing the behavior of the dynamical non-Markovian coefficients.     

Analysis of mixed state entanglement with intrinsic decoherence

We analyze different entanglement measures for a mixed state two-level system in the presence of intrinsic decoherence. The information about entanglement is obtained by comparing the results for the atomic Wehrl entropy and negativity with the analytical results for a simple case. For the strong decoherence case we find that a similar and long-lived maximum Wehrl entropy and negativity between atom and field are shown. The results highlight the important roles played by both the decoherence parameter and the initial state setting in determining the evolution of the atomic Wehrl entropy and negativity.     

Geometric phase of a moving three-level atom

In this paper, we investigate the geometric phase of the field interacting with Ξ-type moving three-level atom. The results show that the atomic motion and the field mode structure play an important roles in the evolution of the system dynamics and geometric phase. We test this observation with experimentally accessible parameters and some new aspects are obtained.     

Entanglement in the Bimodal Jaynes–Cummings Model with the Two-Mode Squeezed Vacuum State

In this paper, we study the interaction between the two-level atom and a bimodal cavity field, namely, two-mode Jaynes–Cummings model when the atom and the modes are initially in the atomic superposition state and two-mode squeezed vacuum state, respectively. For this system we investigate the atomic inversion, linear entropy and atomic Wehrl entropy. We show that there is a connection between all these quantities. Also we prove that the atomic Wehrl entropy exhibits behaviors similar to those of the linear entropy and the von Neumann entropy. Moreover, we show that the bipartite exhibits periodical disentanglement and derive the explicit forms of the states of the atom and the modes at these values of the interaction times.