We present a method to control collisions between ultracold neutral atoms in the electronic ground state and trapped ions. During the collision, the neutral atom is resonantly excited by a laser to a low-field-seeking Rydberg state, which is repelled by the ion. As the atom is reflected from the ion, it is de-excited back into its electronic ground level. The efficiency of shielding is analyzed as

The efficient and simple B-splines variational method is successfully used to calculate Bethe logarithm for the hydrogen atom in the velocity and length gauges. The ground state Bethe logarithm of hydrogen with fourteen accurate figures is obtained in the velocity gauge, and in the length gauge the ground state value has eleven accurate figures. Present velocity- and length-gauge results for the n

In this work, we present a study of hydrogen atoms interacting with hydrogen, nitrogen, and oxygen molecules in the gas phase in order to determine the projectile energy loss, the stopping cross section, and energy deposition with implication in hydrogen and proton dosimetry and radiotherapy. Our calculations are performed with a density-functional tight-binding (DFTB) as well as by an ab initio electron-nuclear

Molecular ions formed in cold hybrid ion–atom experiments may find interesting applications ranging from precision measurements to controlled chemical reactions. Here, we investigate the electronic structure of the ##IMG## [http://ej.iop.org/images/0953-4075/53/13/135303/bab84c5ieqn2.gif] {${\mathrm{Sr}}_{2}^{+}$} molecular ion, which may be produced by photoassociation of laser-cooled Sr + ions immersed

BaF is one of the potential candidates for the experimental search of the electric dipole moment of the electron (eEDM). The NL-eEDM collaboration is building a new experimental set up to measure the eEDM using the BaF molecule (The NL-eEDM collaboration, 2018 Eur. Phys. J. D 72 : 197). To analyze the results of such an experiment, one would require the accurate value of the molecular ##IMG## [http://ej

We numerically simulate gravity-assisted loading of laser-cooled atoms into a hollow-core fiber. For this, we compute the trajectories of falling atoms and test the success or failure of loading with a range of atoms’ initial positions and velocities. By overlapping these results with the position and velocity distribution of the trapped atomic cloud, the number of loaded atoms is estimated without

We present two schemes for error-correction of polarization entanglement with time-bin entanglement and frequency entanglement in hyper-entangled state. In these two protocols, by performing the polarization parity-check operation, the bit-flip and phase-flip errors on the polarization part can be corrected and eliminated in one step. The parties in quantum communication can obtain maximally hyper-entangled

We have reported the results of ab initio calculations of parity- and time-reversal-odd interaction constants for the ground state of alkaline-earth monofluorides. The Kramers-restricted configuration interaction method limited to single and double excitations in conjunction with the quadruple zeta quality basis sets have been employed to perform these four-component relativistic calculations. The

A proposal is given to use the ##IMG## [http://ej.iop.org/images/0953-4075/53/13/135401/bab894bieqn1.gif] {${X}^{1}{\Sigma}\left(v,J,F\right)=\left(0,0,1/2\right)-\left(0,1,1/2\right)$} transition of the HeH + (2.0 THz), NeH + (1.0 THz), and ArH + (0.62 THz) molecular ions as novel frequency standards in the terahertz region. This transition is free from the electric-quadrupole shift, and the DC Stark

In this work, we obtain an analytical representation of the density operator of an atom in a dissipative cavity when the reservoir is at zero temperature and the total number of excitations is N = 1. We also investigated the quantum speed limit time (QSLT) of the atom and the non-Markovianity in the dynamics process. The results show that the QSLT and the non-Markovianity can be effectively manipulated

Exciting molecules with a short strong few cycle IR pulse triggers coherent electronic–nuclear dynamics on multiple electronic states. This creates a new type of initial state where non-adiabatic transfer takes place between already populated electronic states. We explore this new feature using accurate quantal simulations of the ultrafast laser-induced dissociative dynamics in LiH-LiD-LiT series of

We demonstrate that the present superaccurate measurements of transition processes between atomic states in a hydrogen atom reached the limit of accuracy when transition the frequency could not be defined anymore in a unique way. This was predicted earlier and is due to the necessity to include the nonresonant corrections in the description of resonant processes. The observed spectral line profile

Beryllium is being adopted for plasma facing walls in fusion reactors. This has led to the observation of emissions from the A 2 Π state of beryllium hydride. Use of these emissions to monitor Be erosion requires electron impact excitation rates. Cross sections for electron impact vibrational excitation within the X 2 Σ + state and vibrationally resolved electronic excitation to the A 2 Π state are

We theoretically implement the protocol of continuous variable quantum teleportation wherein Alice and Bob share a state built by a linear beam splitter as general two-mode Gaussian entangled state. Using the non-classicality and purity of the two single-mode Gaussian states employed initially at the input of the beam splitter, the unknown state teleportation protocol is explicitly implemented in terms

We study the dynamics of a nonlinear dissipative bosonic Josephson junction with a time-dependent sinusoidal perturbation in the interaction term. We demonstrate parametric resonance, where the system undergoes sustained periodic oscillations even in the presence of dissipation. This happens when the frequency of the perturbation is close to twice the frequency of the unperturbed Josephson oscillations

Variational techniques to calculate estimates of bound-state energies and wave functions for single states are applied to simple electronic systems in magnetic fields. Explicit constraints to other state functions are not required. Our numerical energies compare favourably with results of other calculations, and the speed of our calculations is greatly enhanced by using a separable basis set and analytical

We study both theoretically and experimentally the energy dependence of the low-energy Rb + –Rb total collision rate k ia in the energy range from 10 3 to 10 4 K. We calculate the integral elastic cross-section and the resonant charge-transfer cross-section by the quantum mechanical molecular orbital close-coupling method, and then obtain k ia for temperatures by averaging the cross-sections over a

A recent experiment (Villeneuve et al 2017 Science 356 1150) has shown that two-color photoionization of neon by the combination of an attosecond XUV pulse train and a moderately strong, linearly polarized IR pulse can preferentially produce photoelectrons with orbital angular quantum number l = 3 (f-wave) and magnetic quantum number m = 0. This result was rationalized by the occurrence of different

The complex basis function (CBF) method is a square-integrable ( L 2 ) function method that represents continuum wave functions, and has been applied successfully to various problems, including the calculation of resonance state energies and photoionization cross sections. The previous applications of this method have been limited to non-relativistic problems, and no serious attempt has been made for

As was recently shown in Abumwis et al (2020 Phys. Rev. Lett. 124 193401), many eigenstates of a random Rydberg gas with resonant dipole–dipole interactions are highly delocalized. Although the high degree of delocalization is generic to various types of power-law interactions and to both two and three-dimensional systems, in their detailed aspects the coherence distributions are sensitive to these

We study non-linear absorption of intense monochromatic light through a dense natural rubidium (Rb) vapour. We measure transmission through a 10 cm long heated vapour cell for atom densities up to 3 × 10 19 m −3 and saturation parameters up to 10 4 , for linear and circular polarisation, close to resonance on the 87 Rb D 2 F = 1 → F ′ = 0, 1, 2 transition. The strong absorption at low intensity is

We present a quantum-state-diffusion equation to characterize the dynamics of a generic atomic system due to the coupling to a leaky cavity mode. As quantum resources, the population, the coherence and even the entanglement of the system would gradually leak out of the cavity. The effect from the leakage of the cavity-mode to the uncontrollable degrees of freedom, e.g. environment, is however not always

We have observed formation of Rydberg series superimposed on the Ar ( L 3 M 2,3 M 2,3 ) Auger electron spectral profile with photoexcitation just above the 2p −1 3/2 photoionization threshold. This is due to the recapture of photoelectrons induced by post-collision interaction between the Auger electron and photoelectron: Ar + 2p −1 3/2 + e − → Ar + 3p −2 ml + e − . The intensity distribution of the

The laser-field-modified dipole response of the first ionization threshold of helium is studied by means of attosecond transient absorption spectroscopy. We resolve light-induced time-dependent structures in the photoabsorption spectrum both below and above the ionization threshold. By comparing the measured results to a quantum-dynamical model, we isolate the contributions of the unbound electron

We characterize an attosecond pulse without using a secondary laser pulse. Instead, we use the carrier-envelope-phase dependence of the extreme ultraviolet (XUV) emission to measure the dipole current from a solid material. To confirm, we apply our approach to data derived by solving the time-dependent Schrödinger equation with a periodic potential. Finally, using MgO, we measure the delay shift at

Photoionization calculations of the endofullerene molecule Cl@C 60 with an open-shell chlorine atom are performed in the linear response density functional theory based on a spherical jellium model of C 60 . Cross sections for atom–fullerene hybrid photoemission studied show the effects of the hybridization symmetry, the giant plasmon and the molecular cavity. Comparisons with the results of Ar@C 60

Dirac delta-function potential is widely studied in quantum mechanics because it usually can be exactly solved and at the same time is useful in modeling various physical systems. Here we study a system of delta-potential trapped spin–orbit coupled cold atoms. The spin–orbit coupled atomic matter wave has two kinds of evanescent modes, one of which has a pure imaginary wavevector and is an ordinary

We use exact diagonalization to study an interacting system of N spinless bosons with finite-range Gaussian repulsion, confined in a quasi-two-dimensional harmonic trap with and without an introduced rotation. The diagonalization of the Hamiltonian matrix using Davidson algorithm in subspaces of quantized total angular momentum L z is carried out to obtain the N -body lowest eigenenergy and eigenstate

We model emissions from the Carroll-Yoshino ( v ′ = 0, v ″ = 0) band of molecular nitrogen N 2, i.e. ##IMG## [http://ej.iop.org/images/0953-4075/53/12/125701/jpbab76e6ieqn1.gif] {${{c}_{4}^{{\prime} }}^{1}{{\rm{\Sigma }}}_{u}^{+}(v^{\prime} =0)-X{}^{1}{{\rm{\Sigma }}}_{g}^{+}(v^{\prime\prime} =0),$} due to nonthermal gas discharges in low pressure air and N 2 . In particular, we calculate the rate

We report on a table-top, high-power, terahertz (THz) solid-state emitter driven by few-cycle near-infrared pulses at 16 MHz repetition rate in gallium phosphide (GaP) crystals. Two external nonlinear multi-pass cells are used to shorten the output of a home-built, 100 W, 265 fs, 6.2 μ J Yb:YAG thin-disk oscillator, operating at 1030 nm, to 18 fs with 3.78 μ J pulse energy. The broadband spectrum of

In the present work, we consider the generation of excited nonlinear topological modes of Bose–Einstein condensates. These nonlinear modes present a number of interesting properties and can be used in many applications, such as in matter-wave optics experiments. The resonant generation of nonlinear modes by modulating either the trapping potential or the scattering length have been previously reported

An exact nonlinear model for pointer shift estimation in phase measurement with weak-value amplification is presented, and the necessary assumptions for the linear approximations are discussed. A realistic experimental weak measurement system with pure imaginary weak-value is demonstrated to verify the nonlinear model, and it is shown that our model is effective over a wide dynamic range. In addition

We present three explicit formulas for the number of electronic configurations in an atom, i.e. the number of ways to distribute Q electrons in N subshells of respective degeneracies g 1 , g 2 , …, g N . The new expressions are obtained using the generating-function formalism. The first one contains sums involving multinomial coefficients. The second one relies on the idea of gathering subshells having

Scattering of a Rydberg electron by ground-state atoms (scatterers) located in its classically forbidden region can be viewed as electron-atom scattering with negative incident energy. We propose a treatment of this unusual case of scattering in the context of long-range molecular potentials arising from the interaction of a Rydberg electron with ground state atoms. We describe a treatment leading

High-resolution x-ray spectra were recorded at the National Institute of Standards and Technology electron beam ion trap (EBIT) using two Johann-type crystal spectrometers, with their dispersion planes oriented parallel and perpendicular to the beam direction. The linear polarizations of the 1 s 2 − 1 s 2 l transitions in He-like argon ions were determined from the measured spectra at electron beam

The von Neumann measurement framework describes a dynamic interaction between a target system and a probe. In contrast, a quantum controlled measurement framework uses a qubit probe to control the actions of different operators on the target system, and is convenient for establishing universal quantum computation. In this work, we use a quantum controlled measurement framework for measuring quantum

In this study, the difference detection magnetic optical rotation (MOR) Ramsey-coherent population trapping (CPT) interference fringe signal was taken as the object for research. By solving the optical Bloch equations, the analytic function solution was obtained. An experimental platform was also used to obtain the MOR Ramsey-CPT interference fringe signal experimentally. The experimental results match

Quenching an ultracold bosonic gas in a ring across the Bose–Einstein condensation phase transition is known, and has been experimentally observed, to lead to the spontaneous emergence of persistent currents. The present work examines how these phenomena generalize to a system of two experimentally accessible explicitly two-dimensional co-planar rings with a common interface, or to the related lemniscate

We analyze an angular dependence of the Wigner time delay near the Cooper minimum (CM) of the sub-valent ns shell in argon, krypton and xenon. Such an angular dependence is a result of interplay between the relativistic and correlation effects. The correlation with the outermost np valence shell induces a CM in the sub-valent ns shell which is otherwise CM free. A phase difference between the two spin–orbit

Electronic coherences in molecules are ultrafast charge oscillations on the molecular frame (MF) and their direct observation and separation from electronic population dynamics is challenging. Here we present a valence shell lab frame (LF) scattering method suited to probing electronic coherences in isolated systems. MF electronic coherences lead to LF electronic anisotropies observable by ultrafast

We have measured the photoabsorption spectra of Pb II and Bi III in the wavelength range between 37 and 70 nm. A number of features in the spectra have been identified with the aid of the Cowan suite of atomic codes. 5d → 6p transitions from the ground configuration (5d 10 6s 2 6p) and three excited configurations (5d 10 6s 2 6d, 5d 10 6s 2 7s, 5d 10 6s6p 2 ) give rise to the most prominent features

We investigated the effect of Coriolis coupling (CC) on the initial state-selected dynamics of the H( 2 S) + CH + ( ##IMG## [http://ej.iop.org/images/0953-4075/53/10/105201/jpbab7e1bieqn1.gif] {${X}^{1}{{\rm{\Sigma }}}^{+}$} ) reaction in its electronic ground state ( ##IMG## [http://ej.iop.org/images/0953-4075/53/10/105201/jpbab7e1bieqn2.gif] {$1{}^{2}A^{\prime} $} ) using a time-dependent wavepacket

The spectrum of a hexagonal ring is analysed using concepts of group theory and a tight-binding model with first, second and third neighbours. The two doublets in the spectrum are explained with the C 3 symmetry group together with time-reversal symmetry. Degeneracy lifts are induced by means of various mechanisms. Conjugation symmetry breaking is introduced via magnetic fields, while C 3 breaking

We study time-dependent populations in the excited states of many-electron atoms and molecules with the multiconfiguration time-dependent Hartree–Fock method and reveal the non-stationary behavior of the excited-state populations during field-free propagation originating from the nonlinear character of the equations of motion. We calculate the time-dependent populations of the three lowest singlet

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This study presents an effective scheme for estimating the weak Coulomb force through a hybrid optomechanical system. In this scheme, information regarding the weak Coulomb force can be transferred to the cavity field through the coupling between the cavity field and the mechanical oscillator, and it can be fully extracted from the cavity field when the cavity field and the mechanical oscillator are

We report oxygen K-shell photoabsorption measurements in CO 2 plasmas, using a table-top laser produced plasma soft x-ray (SXR) and extreme ultraviolet source. Significant differences are observed between the photoabsorption spectra of the neutral CO 2 molecule and photoionized CO 2 plasmas, as new spectral features emerge in the case of the latter. These features are attributed to ##IMG## [http://ej

We report on numerical simulations demonstrating the emergence of stroboscopic thermalisation in a chain of atoms submitted to a laser field whose frequency is periodically modulated close to resonance with a transition towards a Rydberg state. We relate the conditions of equilibration of the Rydberg population to the spectrum of the Floquet Hamiltonian and suggest a possible experimental implementation

It is well known that the allowed wavefunctions for an N -electron system should be antisymmetric with respect to the permutation of any pair of electron labels. On the other hand, the Hamiltonian for such a system is invariant under any permutation of electron labels and, consequently, its eigenfunctions are the basis for the irreducible representations of the symmetric group S N . Here, we investigate

Cosmic EUV/x-ray spectroscopists, including both solar and astrophysical analysts, have a wide range of high-resolution and high-sensitivity tools in use and a number of new facilities in development for launch. As this bandpass requires placing the spectrometer beyond the Earth’s atmosphere, each mission represents a major investment by a national space agency such as NASA, ESA, or JAXA, and more

Dark soliton solutions in the one-dimensional classical nonlinear Schrödinger equation have been considered to be related to the yrast states corresponding to the type-II excitations in the Lieb–Liniger model. However, the relation is nontrivial and remains unclear because a dark soliton localized in space breaks the translation symmetry, while yrast states are translationally invariant. In this work

A reduced density matrix (RDM) formalism to simulate the dynamics of core-valence electronic excitation in a metal induced by a femtosecond x-ray laser pulse is presented. The theory is based on the time-dependent unrestricted Hartree–Fock (TDUHF) equation for a one-electron RDM combined with an off-diagonal collision term in the Born approximation (BA), where molecular orbitals (MOs) of a model cluster

We predict quantitatively that it is possible to use few-femtosecond positive or negative time delays , ##IMG## [http://ej.iop.org/images/0953-4075/53/9/095603/jpbab787bieqn1.gif] {${\rm{\Delta }}t,$} between two XUV Gaussian few-femtosecond pulses of moderate intensities and central frequencies ##IMG## [http://ej.iop.org/images/0953-4075/53/9/095603/jpbab787bieqn2.gif] {${\omega }_{1}$} and ##IMG##

Ideal randomness is one of most important conditions for the implementation of continuous-variable quantum key distribution (CVQKD). However, imperfect randomness may exist in a practical CVQKD system due to imperfections in Gaussian modulation or in random-number generators. Here we propose a weak randomness attack model in practical CVQKD systems to investigate the practical performance of the systems

We investigate the time dependence of atom-light and atom-RF field interactions in Rydberg electromagnetically-induced transparency (EIT) in a room-temperature and heated vapour cell. Quantum-optical transients are observed with rapid onset and dissolution of EIT induced by coupler-light pulses. The formulation and dissolution times of EIT, transient signals, and their dependencies on light intensities

We study the generation of high-harmonic beams by the non-collinear wave mixing of two circularly or elliptically polarized fundamental beams. Changing the ellipticity of the two fundamental beams changes the electric field structure in the focal plane, generating multiple high harmonics beamlets. We show that the ellipticity dependence of the harmonic dipole modulates the near-field harmonic intensity

It is normally assumed that induced transitions, by e.g. hyperfine, magnetic field or spin interaction, arise due to mixing in the upper levels. In this paper we discuss an example when mixing in the lower levels through an externally applied magnetic field gives rise to a magnetic field induced transition. We discuss the theory for such a transition and give an example from Fe X, which is relevant

We theoretically study photoelectron angular distributions and related anisotropy parameters for the competition of one- and two-photon ionization of He in an ultrashort extreme-ultraviolet laser pulse, using numerical results from the time-dependent Schrödinger equation. We explore the transition between the two processes for variation of the pulse duration, peak intensity, and central frequency or

A grid of 5285 ab initio points is utilized to construct a 3D potential energy surface (PES) of the ##IMG## [http://ej.iop.org/images/0953-4075/53/9/095202/jpbab7641ieqn3.gif] {${\mathrm{CH}}_{2}({\tilde{X}}^{3}A^{\prime\prime} )$} system. In the calculation procedure, the aug-cc-pV X Z ( X = Q and 5) basis sets with Davidson correction are employed. The reference wave function for the multi-reference

In a previous work Sims and Hagstrom [J. Chem. Phys. 140, 224312 (2014)] reported Hylleraas-Configuration Interaction (Hy-CI) method variational calculations for the neutral atom and positive ion 1S ground states of the beryllium isoelectronic sequence. The Li- ion, nominally the first member of this series, has a decidedly different electronic structure. This paper reports the results of a large,