Initial State Configuration Research Articles

Probing teleported quantum correlations in a two-qubit system inside a coherent field

This paper investigates the impact of dipole interactions and the initial quantum state configurations within a quantum system on teleported quantum correlations involving a pair of qubits embedded in a single-mode field. The analysis encompasses an exploration of non-separability, steerability, non-locality, and steered coherence of the teleported state, considering different initial Bell states for the two-qubit channel. The initial atomic setting state primarily influences the teleported quantum correlations. The study highlights that dipole interaction exert a substantial effect on both the maximum and minimum values of quantum correlations. Furthermore, increasing this interaction demonstrates the potential to enhance control over the decay of correlations induced by the detuning parameter.

An improved method to access initial states in relativistic heavy-ion collisions

Observables in heavy-ion collisions are generally categorized into centralities, which reflect an average over events within a range of impact parameters including a wide variety of initial-state configurations. A multiple binning method using spectator neutrons within each centrality has been shown to provide access to events with rare initial-state conditions. This work suggests an improvement in quantifying the difference between standard centrality and spectator neutron binning towards accessing the initial-state properties. A selection of events with higher initial-state density at a fixed participating nucleon number was observed to result in larger final-state particle production and smaller elliptic flow. The relative difference between observables in centrality and spectator binning shows reduced sensitivity for the observables dominated by impact parameter fluctuations in the initial state, such as triangular flow. This property renders the spectator binning method a good candidate for separating geometric contributions from random fluctuations in the initial state towards final-state observables.

Emergent behaviors of a thermodynamic Cucker‐Smale flock with a time‐delay on a general digraph

We present emergent flocking dynamics of a thermodynamic Cucker‐Smale (TCS) flock on a general digraph with spanning trees under the effect of communication time‐delays. The TCS model describes a temporal evolution of mechanical and thermodynamic observables such as position, velocity and temperature of CS particles. In this paper, we study how variations in mechanical and thermodynamic variables can decay to zero along a time‐independent network with position dependent weights from initial state configuration. For this, we provide a sufficient framework for a mechanical and thermodynamical flocking in terms of initial configuration, network topology, and system parameters. We also present several numerical examples and compare them with analytical results.

Fluid dynamics of heavy ion collisions with mode expansion

The fluid dynamics of a relativistic fireball with longitudinal and transverse expansion is described using a background-fluctuation splitting. Symmetry representations of azimuthal rotations and longitudinal boosts are used for a classification of initial state configurations and their fluid dynamic propagation in terms of a mode expansion. We develop an accurate and efficient numerical scheme based on the pseudo-spectral method to solve the resulting hyperbolic partial differential equations. Comparison to the analytically known Gubser solution underlines the high accuracy of this technique. We also present first applications of FluiduM to central heavy ion collisions at the LHC energies featuring a realistic thermodynamic equations of state as well as shear and bulk viscous dissipation.

Differential many-body effects for initial and core ionic states: impact on XPS spectra

In this paper, the contribution of many-body effects to the X-ray photoelectron spectroscopy, XPS, of an NO molecule is studied using wavefunction theory where the specific consequences of different many-body terms are examined and contrasted. It is shown that there is a differential importance of the many-body effects for the different configurations involved in the XPS. These are the ground, initial state configuration and final, N(1s) and O(1s) core hole ionic configurations. The consequences of the many-body effects are examined for the binding energies, BEs, to the two final state multiplets, triplet, and singlet, for each of the core ions and for the relative intensities of the XPS transitions to these multiplets. The many-body effects examined are those described as static effects that arise for individual terms that are important. The objective is to understand the chemical and physical origins that determine the importance of the correlation effects for the XPS, rather than to obtain very accurate predictions of the BEs. An important theoretical construct that is tested and justified is the equivalent core approximation where the core-ionized atom is replaced by the next higher element in the periodic table. This construct allows us to establish a correlation for the relative importance of the many-body effects in terms of effective charges of the different atoms. This is a correlation that has not been considered before and that we expect may have general relevance. The potential of the effects that we have identified for the XPS of NO to be relevant for the XPS of more complex, condensed phase systems is considered.

Initial state with shear in peripheral heavy ion collisions

In the present work we propose a new way of constructing the initial state for further hydrodynamic simulation of relativistic heavy ion collisions based on Bjorken-like solution applied streak by streak in the transverse plane. Previous fluid dynamical calculations in Cartesian coordinates with an initial state based on a streak by streak Yang-Mills field led for peripheral higher energy collisions to large angular momentum, initial shear flow and significant local vorticity. Recent experiments verified the existence of this vorticity via the resulting polarization of emitted $\mathrm{\ensuremath{\Lambda}}$ and $\overline{\mathrm{\ensuremath{\Lambda}}}$ particles. At the same time parton cascade models indicated the existence of more compact initial state configurations, which we are going to simulate in our approach. The proposed model satisfies all the conservation laws, including conservation of a strong initial angular momentum, which is present in noncentral collisions. As a consequence of this large initial angular momentum we observe the rotation of the whole system as well as the fluid shear in the initial state, which leads to large flow vorticity. Another advantage of the proposed model is that the initial state can be given in both [t,x,y,z] and $[\ensuremath{\tau},x,y,\ensuremath{\eta}]$ coordinates and thus can be tested by all 3+1D hydrodynamical codes which exist in the field.

Mechanism of H adatoms improving the O2 reduction reaction on the Zn-modified anatase TiO2 (101) surface studied by first principles calculation.

First principles calculations were performed to cast insight into the mechanism of the improvement of O2 reduction reaction (ORR) activity by Zn and H interstitials on the anatase TiO2 (101) surface. For the Zn-modified anatase TiO2 (101) surface, both surface and subsurface Zn interstitials could contribute to O2 adsorption and dissociation, but the dissociation barriers of O2 molecules are still too high, which limits the ORR activity. After a H adatom is introduced onto the Zn-modified anatase TiO2 (101) surface, the highest energy barriers are greatly reduced compared with those of the Zn-modified surface. Meanwhile, it is observed that the dissociation barriers decrease almost linearly with the increase of the charge difference of adsorption O2 between initial and transition state configurations. Specifically, subsurface Zn and surface H interstitials facilitate O2 dissociation and subsequent oxidation reactions, and further frequency analysis shows that these dissociation processes are frequent even at the room temperature of 300 K. In a word, this work provides a theoretical support to design a high ORR activity catalyst of the TiO2 nanocrystal comparable to precious Pt catalysts.

Correlated Event-by-Event Fluctuations of Flow Harmonics in Pb-Pb Collisions at sqrt[s_{NN}]=2.76 TeV.

We report the measurements of correlations between event-by-event fluctuations of amplitudes of anisotropic flow harmonics in nucleus-nucleus collisions, obtained for the first time using a new analysis method based on multiparticle cumulants in mixed harmonics. This novel method is robust against systematic biases originating from nonflow effects and by construction any dependence on symmetry planes is eliminated. We demonstrate that correlations of flow harmonics exhibit a better sensitivity to medium properties than the individual flow harmonics. The new measurements are performed in Pb-Pb collisions at the center-of-mass energy per nucleon pair of sqrt[s_{NN}]=2.76 TeV by the ALICE experiment at the Large Hadron Collider. The centrality dependence of correlation between event-by-event fluctuations of the elliptic v_{2} and quadrangular v_{4} flow harmonics, as well as of anticorrelation between v_{2} and triangular v_{3} flow harmonics are presented. The results cover two different regimes of the initial state configurations: geometry dominated (in midcentral collisions) and fluctuation dominated (in the most central collisions). Comparisons are made to predictions from MonteCarlo Glauber, viscous hydrodynamics, ampt, and hijing models. Together with the existing measurements of the individual flow harmonics the presented results provide further constraints on the initial conditions and the transport properties of the system produced in heavy-ion collisions.

Impurity entanglement through electron scattering in a magnetic field

We study the entanglement of magnetic impurities in an environment of electrons through successive scattering while an external magnetic field is applied. We show that the dynamics of the problem can be approximately described by a reduced model of three interacting spins, which reveals an intuitive view on how spins can be entangled by controlled electron scattering. The role of the magnetic field is rather crucial. Depending on the initial state configuration, the magnetic field can either increase or decrease the resulting entanglement but more importantly it can allow the impurities to be maximally entangled.

Classification of initial state granularity via 2D Fourier expansion

A new method for quantifying fluctuations in the initial state of heavy ion collisions is presented. The initial state energy distribution is decomposed with a set of orthogonal basis functions which include both angular and radial variation. The resulting two-dimensional Fourier coefficients provide additional information about the nature of the initial state fluctuations compared to a purely angular decomposition. We apply this method to ensembles of initial states generated by both Glauber and color glass condensate Monte-Carlo codes. In addition initial state configurations with varying amounts of fluctuations generated by a dynamic transport approach are analyzed to test the sensitivity of the procedure. The results allow for a full characterization of the initial state structures that is useful to discriminate the different initial state models currently in use.Communicated by Steffen Bass

DoubleK-shell photoionization of atomic beryllium

Double photoionization of the core $1s$ electrons in atomic beryllium is theoretically studied using a hybrid approach that combines orbital and grid-based representations of the Hamiltonian. The ${}^{1}\phantom{\rule{-0.16em}{0ex}}S$ ground state and ${}^{1}\phantom{\rule{-0.16em}{0ex}}P$ final state contain a double occupancy of the $2s$ valence shell in all configurations used to represent the correlated wave function. Triply differential cross sections are evaluated, with particular attention focused on a comparison of the effects of scattering the ejected electrons through the spherically symmetric valence shell with similar cross sections for helium, representing a purely two-electron target with an analogous initial-state configuration.

Validity of the Wannier threshold law for angular correlation width in double photoionization of atoms

We calculated ab initio the three-fold differential cross section of a double single-photon Helium photoionization at equal energy sharing, and obtained from one the Gaussian width parameter, describing the angular interelectron correlations, for the total electrons energies range E from 0.1 eV to 100 eV. The results are in excellent agreement with experimental data but indicate that the Wannier threshold law for angular distribition is not correct at energies attainable in modern experiments. It is shown that the Gaussian width parameter dependence on energy is much better described by the modified threshold law, obtained by Kazansky and Ostrovsky [J. Phys. B 26, 2231 (1993)]. Also, we explored the Gaussian width parameter for a double photoionization of the targets with the strongly asymmetrical initial state configuration: the atomic Hydrogen negative ion and the Helium in the 2s1S and 3s1S excited states. We found that the Gaussian width parameter dependence on the total ejected electrons energy for this targets has a maximum at low energies. We show also that the correlation parameter dependence on the interelectron angle for these targets is essentially non-Gaussian and has a number of peaks equal to a number of initial state radial nodes, that reveals the new abilities for the qualitative analysis of electron structure.

Fluctuations and transverse momentum distributions in the color clustering approach

We present our results on transverse momentum fluctuations, multiplicity fluctuations and transverse momentum distributions for baryons and mesons in the framework of the clustering of color sources. We determine under what conditions the initial state configurations can lead to color connection, and more specifically, if variations of the initial state can lead to a transition from disconnected to connected color clusters, modifying the number of effective sources. We find that beyond a critical point, one has a condensate, containing interacting and hence color-connected sources. This point thus specifies the onset of color deconfinement. We show that the transverse momentum and multiplicity distributions are related to each other in a defined way. We obtain a non-monotonic dependence of the pT and multiplicity fluctuations with the number of participants. We present our results for the fluctuations and the transverse momentum distributions at RHIC energies compared to the existing experimental data and our predictions for LHC energies.

Electronic structure ofCeFeAsO1−xFx(x=0, 0.11, and 0.12)

We report an extensive study on the intrinsic bulk electronic structure of the high-temperature superconductor ${\text{CeFeAsO}}_{0.89}{\text{F}}_{0.11}$ and its parent compound CeFeAsO by soft and hard x-ray photoemissions, x-ray absorption, and soft x-ray emission spectroscopies. The complementary surface/bulk probing depth, and the elemental and chemical sensitivity of these techniques allow resolving the intrinsic electronic structure of each element and correlating it with the local structure, which has been probed by extended x-ray absorption fine-structure spectroscopy. The measurements indicate a predominant $4{f}^{1}$ (i.e., ${\text{Ce}}^{3+}$) initial-state configuration for cerium and an effective valence-band-to-$4f$ charge-transfer screening of the core hole. The spectra also reveal the presence of a small $\text{Ce}\text{ }{f}^{0}$ initial-state configuration, which we assign to the occurrence of an intermediate-valence state. The data reveal a reasonably good agreement with the partial density of states as obtained in standard density-functional calculations over a large energy range. Implications for the electronic structure of these materials are discussed.

Interference effects in the decay of the3d→5p,6pexcitations of Kr studied with fluorescence spectroscopy

The energy dependence of the fluorescence intensity from the $4{p}^{4}(^{1}D)5p$ states of Kr was studied experimentally across the $3{d}_{5/2}^{\ensuremath{-}1}5p$, $3{d}_{3/2}^{\ensuremath{-}1}5p$, and $3{d}_{5/2}^{\ensuremath{-}1}6p$ resonances. The results of multiconfiguration Dirac-Fock calculations were compared with the measurements and with earlier calculations. The calculated interference effects in the resonant Auger process were found to be very sensitive to the initial state configuration interaction. The addition of the $7p$ orbital in the wave functions did not improve the agreement between experiment and calculation. The effects of cascade processes were also considered with the help of Hartree-Fock calculations.

Inferring particle distribution in a proton accelerator experiment

A beam of protons is produced by a linear charged particle accelerator, then focused through the use of successive quadrupoles. The initial state of the beam is unknown, in terms of particle position and momentum. Wire scans provide the only available data on the current state of the beam as it passes through and beyond the focusing region; the goal is to infer the initial state from these position histograms. This setup is that of an inverse problem, in which a computer simulator is used to link an initial state configuration to observable values (wire scans), and then inference is performed for the distribution of the initial state. Our Bayesian approach allows estimation of uncertainty in our initial distributions and beam predictions.

INTERACTION OF HIGHLY CHARGED Xeq+ (q = 26, 27, 30) IONS WITH MOLYBDENUM SURFACE

Experimental investigation of Molybdenum L-shell X-ray emission is reported in the collision of highly charged Xe q+ (q = 26,27,30) ions with Molybdenum surface in the energy range 400 to 600 keV. Based on the X-ray spectra obtained and by the extrapolation of experimental data to the lower incident energy range, a limit was found for the energy of the incident ions. The influence of initial charge state on X-ray emission from the target L-shell was observed. The difference of the initial charge state and electron configuration of the incident ions may lead to observably different contribution to the target atom vacancy production and L-shell X-rays emission. Based on COB model, a simple explanation was presented to interpret the features of the experimental results.

Effect of semiclassical molecular initial ground state configuration on the neutron spectra in the interactions ofp+Al,Fe, andZrat 1.2 GeV

We studied the effect of the semiclassical molecular initial ground state configuration of the nucleus on the neutron spectra for $p+\mathrm{Al},\phantom{\rule{0.3em}{0ex}}\mathrm{Fe}$, and $\mathrm{Zr}$ at 1.2 GeV by using an improved ultrarelativistic quantum molecular dynamics (ImUrQMD) model. Compared to the standard UrQMD version, it incorporates: (i) Pauli potential, (ii) a medium modified $\mathrm{NN}\ensuremath{\rightarrow}N\ensuremath{\Delta}$ angular distribution, and (iii) a statistical multifragmentation decay model as an afterburner. It is shown that the slow evaporated, cascade, and quasielastic (inelastic) peaks of neutrons are all sensitive to different initialization procedures. Therefore, the implementation of a proper semiclassical ground state initialization in the ImUrQMD model is of importance for the description of all the neutron spectra in proton-induced reactions at intermediate energies $(\ensuremath{\approx}1\mathrm{GeV})$.

Additive and multiplicative noise driven systems in1+1dimensions: Waiting time extraction of nucleation rates

We study the rate of true vacuum bubble nucleation numerically for a ${\ensuremath{\varphi}}^{4}$ field system coupled to a source of thermal noise. We compare in detail the cases of additive and multiplicative noise. We pay special attention to the choice of initial field configuration, showing the advantages of a version of the quenching technique. We advocate a new method of extracting the nucleation time scale that employs the full distribution of nucleation times. Large data samples are needed to study the initial state configuration choice and to extract nucleation times to good precision. The $1+1$ dimensional models afford large statistics samples in reasonable running times. We find that for both additive and multiplicative models, nucleation time distributions are well fit by a waiting time, or gamma, distribution for all parameters studied. The nucleation rates are a factor 3 or more slower for the multiplicative compared to the additive model with the same dimensionless parameter choices. Both cases lead to high confidence level linear fits of $\mathrm{ln}\ensuremath{\tau}\mathrm{vs}{T}^{\ensuremath{-}1}$ plots, in agreement with semiclassical nucleation rate predictions.

Resonant photoemission applied to transition-metals, rare-earths, and actinides

Abstract Recent experimental results concerning the application of resonant photoemission to late 3d-transition metals, rare-earth systems, and uranium metal are presented. Special attention is paid to angle-resolved valence-band studies, that allow a determination of spatial localization and angular momentum character of Bloch states across the Brillouin zone. For f-emissions, the influence of different initial and final state configurations on the resonant behavior is discussed. For 3d-transition metals, the question discussed is, whether the resonant enhancement of satellite structures should really be interpreted in terms of Fano-resonances, or the spectra should be described by an incoherent superposition of photoemission and Auger signals.