Dynamic properties of wehrl information entropy and wehrl phase distribution for a moving four-level atom

We study the dynamics of the von Neumann entropy, Wehrl entropy, and Wehrl phase distribution for a single four-level ladder-type atom interacting with a one-mode cavity field taking into account the atomic motion. We obtain the exact solution of the model using the Schr¨odinger equation under specific initial conditions. Also we investigate the quantum and classical quantifiers of this system in the nonresonant case. We examine the effects of detuning and the atomic motion parameter on the entropies and their density operators. We observe an interesting monotonic relation between the different physical quantities in the case of nonmoving and moving atoms during the time evolution. We show that both the detuning and the atomic motion play important roles in the evolution of the Wehrl entropy, its marginal distributions, entanglement, and atomic populations.     

Erratum to “Effect of the time-dependent coupling on a superconducting qubit-field system under decoherence: Entanglement and Wehrl entropy” [Ann. Physics 361 (2015) 247–258]

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.     

A geometric phase for superconducting qubits under the decoherence effect

We propose a relaxation rate or dissipative cavity-based parameters that can be used as indicators of the stationary limit of a mixed state geometric phase. We perform our considerations for the system of a superconducting qubit in an open transmission line or interacting with a dissipative cavity. This system is very useful for performing an effective quantum computation by exhibiting the long collapse time of the geometric phase. It is shown that the geometric phase in the stationary limit does not depend on interaction time if the decay time exceeds an upper bound.     

Kinetics and mechanism of oxidation oftrans-1,2-diaminocyclohexanetetraacetatocobaltate(II) by periodate

Summary The kinetics of oxidation oftrans-1,2-diaminocyclohexanetetraacetatocobaltate(II), Co^IICDTA^2–, by periodate were studied using either excess periodate or excess complex concentrations. When periodate was in excess the reaction showed first-order dependence on [IO ₄ ^– ] and first-order and second-order dependences on [Co^IICDTA^2–]. First-order dependence in each reactant was obtained when the complex was in excess. The reaction rate was found to be independent of pH over the range 4–5, but increasing with increasing ionic strength. The enthalpy and the entropy of activation were calculated using the transition state theory equation.     

Information entropy and entanglement of a superconducting qubit coupled to a cavity field with its spontaneous decay

The quantum entanglement between superconducting qubit and cavity field is described quantitatively in the presence of spontaneous decay. Depending on how how a system is quantum correlated with its environment, the entanglement dynamics between the qubit and cavity is evaluated and investigated during the dissipative process. The motivation based on recent experiments wherein the Cooper box can be used to probe the decay of the resonator superposition state due to environmental decoherence, we theoretically investigate the dynamics of entanglement measured by the negativity. Wehrl entropy and Wehrl phase distribution of a superconducting qubit coupled to a cavity field induced by a superconducting qubit-damping reservoir governed by a master equation.     

Quantum quantifiers of Raman photon pairs with relativistic motion

In this paper, we develop a model for four-level double Raman pairs by exploiting the required optimal conditions for this system that are feasible with real experimental realization. We investigate qualitatively the entanglement, statistical properties, and geometric phase for the pair of Stokes and anti-Stokes photons in the presence of the relativistic motion. We show that these quantifiers are very sensitive to the change of the Rabi frequency under relativistic motion, exhibiting substantial phenomena that depend on this kind of the coupling between the atom and photons. Finally, we explore the relationship between the quantum quantifiers for constant and time-dependent coupling.     

Interaction of a Three-Level Atom and Field in a Squeezed Vacuum State with Added Photons: Quantum Phase and Nonclassical Properties

We present a detail study of the evolution of nonlocal correlations of an interacting quantum system comprising a three-level atom and a field mode initially prepared in a squeezed vacuum state with added photons. We compare the dynamical behavior of the quantum phase and entanglement by varying the number of photons added to the squeezed vacuum state. Furthermore, we examine the influence of the added-photon number and the squeeze parameter on the dynamical behavior of entanglement, quantum phase, and nonclassical properties of the field. Moreover, we explore the link between the quantum phase and the nonlocal correlation. Finally, we introduce an effective method to generate and maintain a high level of entanglement for this quantum system based on precise parameter ranges.     

Utility of 2,3-dichloro-5,6-dicyano-p-benzoquinone in assay of codeine, emetine and pilocarpine

A simple and sensitive spectrophotometric method for the assay of codeine, emetine and pilocarpine is described, based on the interaction of these drugs (as n-electron donors) with 2,3-dichloro-5,6-dicyano-p-benzoquinone (as pi -acceptor) to give a highly coloured radical anion which exhibits maximum absorption at 460 nm. Formation of the radical anion has been established by electron spin resonance measurements. Beer's law is obeyed for the alkaloids investigated. The assay results are in accord with pharmacopoeial assay results. The procedure is sufficiently sensitive to permit unit dose assay of the individual alkaloids in pharmaceutical formulations.     

Solvent effect on rate and mechanism of oxidation of chromium(III) by periodate

Summary The kinetics of chromium(III) oxidation by periodate were studied in various EtOH–H₂O solvent mixtures covering the 0.0 to 58.0 wt% EtOH range, at five different temperatures in the 15–35°C range. The rate of reaction increases with increasing EtOH content. Thermodynamic activation parameters have been calculated and an appropriate mechanism is suggested.     

Tavis–Cummings Model with Moving Atoms

In this work, we examine a nonlinear version of the Tavis–Cummings model for two two-level atoms interacting with a single-mode field within a cavity in the context of power-law potentials. We consider the effect of the particle position that depends on the velocity and acceleration, and the coupling parameter is supposed to be time-dependent. We examine the effect of velocity and acceleration on the dynamical behavior of some quantumness measures, namely as von Neumann entropy, concurrence and Mandel parameter. We have found that the entanglement of subsystem states and the photon statistics are largely dependent on the choice of the qubit motion and power-law exponent. The obtained results present potential applications for quantum information and optics with optimal conditions.