Stark Shift Parameter Research Articles

Preservation and enhancement of quantum correlations under Stark effect

We analyse the dynamics of quantum correlations by obtaining the exact expression of Bures distance entanglement, trace distance discord, and local quantum uncertainty of two two-level atoms. Here, the atoms undergo two-photon transitions mediated through an intermediate virtual state where each atom is separately coupled to a dissipative reservoir at zero temperature in the presence of the Stark shift effect. We have investigated the dynamics of this atomic system for two different initial conditions of the environment. In the first case, we have assumed the environment's state to be in ground state and in the other case, we have assumed the state to be in the first excited state. The second initial condition is significant as it shows the role played by both the Stark shift parameters in contrast to only one of the Stark shift parameters for the first initial condition. Our results demonstrate that quantum correlations can be sustained for an extended period in the presence of Stark shift effect in the case of both Markovian and non-Markovian reservoirs. The effect in the non-Markovian reservoir is more prominent than the Markovian reservoir, even for a very small value of the Stark shift parameter. We observe that among the correlation measures considered, only local quantum uncertainty is accompanied by a sudden change phenomenon, i.e. an abrupt change in the decay rate of a correlation measure. Our findings are significant as preserving quantum correlations is one of the essential aspects in attaining optimum performance in quantum information tasks.

Effect of stark shift on three-level atom interacting with a correlated two-mode of non-linear coherent state

In this manuscript, we study a new non-linear system which represents a ?-type five level atom interacting with a quantized four-mode electromagnetic field. A non-linear Stark shift is introduced, through the elimination of intermediate levels (two and four) using the adiabatic elimination technique. By using the Schrodinger equation we obtain the analytic solution this model. Some statistical aspects through the effective Hamiltonian are presented such as the collapses-revivals phenomenon, degree of purity, concurrence, and the squeezing phenomenon with respect to study the effect of Stark shift parameters on these statistical aspects. For small values of the Stark shift parameter, the collapse times increase and the atomic inversion symmetry axis shifts upward, while the entanglement decreases significantly. It has been noted that the system is affected by the Stark shift parameter.

Effect of Stark shift on nonlocal correlation of two atoms in a cavity containing a parametric amplifier and a Kerr like medium

An analytical solution is obtained for a system consisting of two atoms interacting with a nondegenerate parametric amplifier of a cavity field containing a Kerr like medium in the presence of Stark shift terms. The nonlinearity of the interaction leads to the generation of different nonlocal correlations (NLCs) beyond entanglement concurrence, which are measured by uncertainty-induced quantum nonlocality and maximal Bell’s function. It is found that the generation of the NLCs, due to the atom-cavity unitary interaction, can be controlled by the nonlinearity of the Kerr like medium and the Stark shift. The Kerr like medium and the Stark shift lead to reduce the regularity and the amount of the generated nonlocal correlations. The reduction in the generated nonlocal correlations, due to the Kerr like medium, is increased by the increase in the Stark shift parameter and vice versa.

Influence of Stark-shift on quantum coherence and non-classical correlations for two two-level atoms interacting with a single-mode cavity field

An exact analytic solution for two two-level atoms coupled with a multi-photon single-mode electromagnetic cavity field in the presence of the Stark shift is derived. We assume that the field is initially prepared in a coherent state and the two atoms are initially prepared in excited state. Considering the atomic level shifts generated by the Stark shift effect, the dynamical behavior of both quantum coherence (QC) measured using a quantum Jensen–Shannon divergence and of quantum correlations captured by quantum discord (QD) are investigated. It is shown that the intensity-dependent Stark-shift in the cavity and the number of coherent state photons plays a key role in enhancing or destroying both QC and QD during the process of intrinsic decoherence. We remarked that increasing the Stark-shift parameters, the frequencies of the transition for the mode of the cavity field, and photons number destroy both the amount of QC and QD and affected their periodicity. More importantly, QC and QD exhibit similar behavior and both show a revival phenomenon. We believe that the present work shows that the quantum information protocols based on physical resources in optical systems could be controlled by adjusting the Stark-shift parameters.

Determination of Stark Shifts and Widths Using Time Resolved Laser-Induced Breakdown Spectroscopy (LIBS) Measurements.

Stark broadening parameters have been estimated for resonant lines of Al(I) using time resolved measurements. The relation between the various emission line characteristics at different phases of opacity have been utilized to obtain the value of plasma temperature and Stark width parameters from the experimental data. The observed value of the center line intensity and Lorentzian component of the line width are compared against a simulated value of these parameters for optically thin case. The plasma temperature and Stark broadening parameters are obtained for the best fit condition by matching the experimentally observed and the simulated values of intensity and line widths. The time resolved measurements result in much better estimates for Stark parameters by allowing multiple points for fitting keeping the number of variables limited. The Stark shift parameters are also obtained from the slope of the plot of observed central wavelength shifts versus observed electron number density which is measured as a function of time. Hence, a method utilizing multiple-time observation data to obtain the Stark broadening parameters for lines showing self-absorption has been demonstrated.

Effects of Kerr Medium and Stark Shift Parameter on Wehrl Entropy and the Field Purity for Two-Photon Jaynes–Cummings Model Under Dispersive Approximation

We estimate the quantum state of a two-level atom and the coherent field in a Kerr medium subject to the cavity damping. The density matrix of the field is considered within the framework of the dispersive approximation. We study dynamical properties of the linear entropy, Wehrl entropy, and the Wehrl phase density during the time of interaction. The effects of the Kerr medium and cavity damping on the time evolution of different quantities are examined. The results refer to the sensitivity of these aspects to changes either in the decay parameter or in the Kerr-like medium and Stark-shift parameters. Linear entropy and nonclassical properties of the field quantified by the Wehrl entropy are also very sensitive to the Kerr medium and Stark-shift parameter.

Nonclassical properties and field entropy squeezing of the dissipative two-photon JCM under Kerr like medium based on dispersive approximation

The quantum state of a two-level atom and coherent field in Kerr medium under cavity damping effect is evaluated. The field density matrix of the system is given based on the dispersive approximation. The dynamical properties of Mandel parameter as a quantifier of the nonclassical properties for a radiation field during the interaction time are studied. The position and momentum components of entropy squeezing under Kerr like medium within dispersive approximation are investigated. The effect of initial field state consideration, Kerr medium, Stark shift terms and parameter of cavity damping on the time evolution of different quantities are examined. The results show that the entropy squeezing and non-classical properties are very sensitive to the Kerr medium and initial state of the field. The proposed system resists the damping when the field initially in statistical mixture of coherent state that the coherent state itself.

Dynamics and maintenance of bipartite entanglement via the Stark shift effect inside dissipative reservoirs

In this paper, the exact entanglement dynamics are obtained of two two-level atoms with two-photon transitions accompanied by the Stark shift, where each atom is independently coupled to a dissipative reservoir at zero temperature. The results show that, in the presence of Stark shift, entanglement can be preserved for a long time and the decoherence process of entanglement slows down. In particular, we find that while the Stark shift has a constructive effect on entanglement protection for both Markovian and non-Markovian reservoirs, this positive effect can be more visible in the non-Markovian reservoir even with low Stark shift parameter values.

Stark broadening of several Bi iv spectral lines of astrophysical interest

The presence of spectral lines of bismuth in stellar atmospheres has been reported in different stars. The anomalous values of the spectral intensities of Bi II and Bi III, compared to the theoretical Local Termodinamic Equilibrium (LTE) standards of Bi I/Bi II/Bi III, have been reported in the spectra obtained with the High Resolution Spectrograph of the Hubble/Goddard Space Telescope in the chemically peculiar stars HgMn stars χ Lupi and HR 7775. Spectral lines of 1436.8, 1902.3, 2630.9 and 2936.7 A of Bi II and 1423.4 A of Bi III were reported and their relative intensities were measured in these studies Litzen & Wahlgren 2002. These lines are overlapped with spectral lines of 1437.65, 2630.1 and 2937.1 A of Bi IV. A study of the Stark broadening parameters of Bi IV spectral lines can help to study these overlaps. In this paper, using the Griem semi-empirical approach, we report calculated values of the Stark parameters for 64 spectral lines of Bi IV. The matrix elements used in these calculations have been determined from 17 configurations of Bi IV. They were calculated using the COWAN code including core polarization effects. Data are displayed for an electron density of 10¹⁷ cmˉ³ and temperatures T=10 000–160 000 K. Also calculated radiative lifetimes for 12 levels with experimental lifetime are presented, in order to test the goodness of our calculations. Theoretical trends of the Stark width and shift parameters versus the temperature for spectral lines of astrophysical interest are displayed.

Quantum phase transition and Berry phase of the Dicke model in the presence of the Stark-shift

In this paper, we employ the energy surface method to study a system of a two-level atom Bose–Einstein condensate coupled to a high-finesse optical cavity interacting with a single-mode electromagnetic field in the presence of the Stark-shift. The energy surface, the Phase transitions and the Berry phase of the two-level atom in Dicke model are obtained. Employing the Holstein–Primakoff representation of the angular momentum Lie algebra, the coupling line separation of the normal phase and the superradiant phase which occurs in a collection of fluorescent emitters (such as atoms), between a state containing few electromagnetic excitations are studied and a mean field description of the Dicke model is presented. We notice that in the thermodynamic limit, the energy surface takes a simple form for a direct description of the phase transition. Moreover, we show that the Stark-shift parameters and the atom–atom interactions can strongly affect the phase transition point. The results in the absence of the Stark-shift agree precisely with those obtained by Li, Liu and Zhou, who studied the same model using a different method.

Donor hyperfine Stark shift and the role of central-cell corrections in tight-binding theory

Atomistic tight-binding (TB) simulations are performed to calculate the Stark shift of the hyperfine coupling for a single arsenic (As) donor in silicon (Si). The role of the central-cell correction is studied by implementing both the static and the non-static dielectric screenings of the donor potential, and by including the effect of the lattice strain close to the donor site. The dielectric screening of the donor potential tunes the value of the quadratic Stark shift parameter (η2) from −1.3 × 10−3 µm2 V−2 for the static dielectric screening to −1.72 × 10−3 µm2 V−2 for the non-static dielectric screening. The effect of lattice strain, implemented by a 3.2% change in the As–Si nearest-neighbour bond length, further shifts the value of η2 to −1.87 × 10−3 µm2 V−2, resulting in an excellent agreement of theory with the experimentally measured value of −1.9 ± 0.2 × 10−3 µm2 V−2. Based on our direct comparison of the calculations with the experiment, we conclude that the previously ignored non-static dielectric screening of the donor potential and the lattice strain significantly influence the donor wave function charge density and thereby leads to a better agreement with the available experimental data sets.

Stark shift and field ionization of arsenic donors in 28Si-silicon-on-insulator structures

We develop an efficient back gate for silicon-on-insulator (SOI) devices operating at cryogenic temperatures and measure the quadratic hyperfine Stark shift parameter of arsenic donors in isotopically purified 28Si-SOI layers using such structures. The back gate is implemented using MeV ion implantation through the SOI layer forming a metallic electrode in the handle wafer, enabling large and uniform electric fields up to 2 V/μm to be applied across the SOI layer. Utilizing this structure, we measure the Stark shift parameters of arsenic donors embedded in the 28Si-SOI layer and find a contact hyperfine Stark parameter of ηa = −1.9 ± 0.7 × 10−3 μm2/V2. We also demonstrate electric-field driven dopant ionization in the SOI device layer, measured by electron spin resonance.

Dynamics of a three level atom interacting with a detuned SU (1,1) quantum system

Starting from the interaction between a 3-level atom in the cascade configuration with an SU(1, 1) quantum system, an effective Hamiltonian for a 2-level atom with the presence of a Stark shift structure is obtained under large detuning and adiabatic elimination. The evolution operator for the new system is obtained and expectation values for different dynamical observables are obtained taking the initial state of the SU(1, 1) system to be a Perelomov coherent state and a superposition state for the 2-level atom. Atomic inversion, atomic variable squeezing and degree of entanglement are investigated for various values of the involved parameters. The effect of the Stark shift parameters is displayed in these phenomena.

Effects of Stark shift and decoherence terms on the dynamics of phase-space entropy of the multiphoton Jaynes Cummings model

The time evolution of the Wehrl entropy and Wehrl phase distribution for the multiphoton Jaynes Cummings model, where the dynamics is described by the phase-damped terms, is studied. Analytical and numerical results under certain parametric conditions are obtained by means of which we analyze the influence of dissipation on the dynamics of Husimi Q-function, Wehrl entropy and Wehrl phase distribution for different values of the Stark shift parameter. Our results show that information about the dynamical properties of the system can be obtained through the Wehrl entropy and Wehrl phase distribution from the point of view of phase-space information. An interesting relation between the correlation, Stark shift and decoherence effect is observed.

Entangled two two-level atoms interacting with a cavity field in the presence of the stark shift terms

The general solution of the problem of two two-level atoms with degenerate two-photon transitions interacting with a cavity single-mode radiation field in the presence of the Stark shift terms is obtained. The temporal evolution of the atomic inversion for the single-atom case, the entropy squeezing and the atomic variances squeezing are studied. We use the linear entropy and von Neumann entropy to measure the degree of entanglement between the atoms and the field. It has shown that an increase in the value of the Stark shift parameter leads to an increase in the degree of entanglement. These aspects are sensitive to changes in the Stark shift parameter.

New features of a single-mode nonlinear Stark shift in the presence of phase damping

The influence of the nonlinear Stark shift, for the multi-quanta JCM in the presence of phase damping is studied. In particular the temporal evolution of the atomic inversion, the linear entropy and the entropy squeezing are investigated. The linear entropy is used as an indicator of the degree of entanglement between the atom and the field. The results indicate the sensitivity of these aspects to changes either in the decay parameter or the Stark shift parameter.

Effect of the Stark shift on entanglement in a double Jaynes-Cummings model in thermal environment

Considering a double two-photon Jaynes-Cummings (J-C) model, we study the effects of Stark shift and mean photon number on entanglement between two two-level atoms when the atoms are initially in a maximally entangled state and the fields are in the single-mode thermal fields. The results show that the two atoms evolve periodically into a disentangled separable state when Stark shift is not considered. However, in the presence of Stark shift, the two two-level atoms are no longer disentangled and long-lived entanglement can be obtained. For a larger value of the Stark shift parameter and a smaller mean photon number, the two atoms can remain in a stationary entangled state. These properties show that the Stark shift can be used to control entanglement in the double two-photon J-C model under the influence of thermal environment.

New Aspects of Field Entropy Squeezing as an Indicator for Mixed State Entanglement in an Effective Two-Level System with Stark Shift

We present an effective two-level system in interaction through two-photon processes with a single mode quantized electromagnetic field, initially prepared in a coherent state. Field entropy squeezing as an indicator of the entanglement in a mixed state system is suggested. The temporal evolution of the negativity, Wehrl entropy, Wehrl phase distribution and field entropy squeezing are investigated. The results highlight the important roles played by both the Stark shift parameters and the mixed state setting in the dynamics of the Wehrl entropy, Wehrl phase distribution and field entropy squeezing.

ENTANGLEMENT OF A TWO-LEVEL ATOM INTERACTING WITH A NEW STRUCTURE OF A GENERALIZED NONLINEAR STARK SHIFT VIA Ξ CONFIGURATION

The problem of a two-level atom interacting with single mode cavity field is considered, however, the optical cavity is filled with new structure of a generalized nonlinear Stark shift via Ξ configuration. One starts with a three-level trapped atom interacting with the quantized field of center of mass motion thus a Hamiltonian for one-phonon process with nonlinearities is derived. Through the elimination of the intermediate level by using the adiabatic elimination method, we generate a new structure of effective Hamiltonian for a two-level atom with a nonlinear Stark shift. The temporal evolution of the atomic inversion is studied, we introduce that in the presence of the Stark shift parameter the atom leaves in a maximal entangled sate. We use the von Neuman entropy to measure the degree of entanglement between the atom and the field. After adding the nonlinear Stark shift the system never reaches the pure state. Also we study the Q-function for obtaining more information in phase space for this system. These aspects are sensitive to changes in the Stark shift parameter. The results shows that the effect of the nonlinearity in the Stark shift changes the quasiperiod of the field entropy and hence the entanglement between the particle and the field.

Influence of the Stark Shift on Entanglement Sudden Death and Birth in Cavity QED

We investigate the entanglement dynamics of two two-level atoms interacting with two vacuum fields of two spatially separated cavities with the Stark effects by employing the concurrence. It is shown that the entanglement sudden death (ESD) and birth (ESB) could be controlled by adjusting the Stark-shift parameters. If the Stark-shift parameters are chosen appropriately, then ESD and ESB phenomena will appear. In addition, the appearance of ESD before or after ESB depends on the Stark-shift values.