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The photodetachment of the ##IMG## [http://ej.iop.org/images/0953-4075/53/18/185102/baba203ieqn20.gif] {${\text{H}}_{2}^{-}$} ion in a time-dependent electric field is investigated for the first time. On the basis of time-dependent closed orbit theory, we calculate the photodetachment cross section (PCS) of a ##IMG## [http://ej.iop.org/images/0953-4075/53/18/185102/baba203ieqn21.gif] {${\text{H}}_{2}^{-}$}

A multielectron wave-packet propagation method was used to calculate the electronic decay of oxygen and fluorine 2 s vacancies for a group of trifluoroalkyl alcohols, HOC n H (2 n −1) F 3 , with n between 1 and 5. Whether ionizing O2 s or F2 s orbitals, it is shown that an electron can be emitted non-locally from the opposite terminus of the molecule. The decay of the O(2 s −1 ) state is found to be

Resonant inelastic x-ray scattering spectra excited at the fluorine K resonances of SF 6 have been recorded. While a small but significant propensity for electronically parity-allowed transitions is found, the observation of parity-forbidden electronic transitions is attributed to vibronic coupling that breaks the global inversion symmetry of the electronic wavefunction and localizes the core hole

We propose two different designs of slotted photonic crystal nanofiber cavities (SPCNCs), dielectric-mode (DM) SPCNC and air-mode (AM) SPCNC, and numerically investigate their refractive index sensing performances when they are immersed in an aqueous environment. By using the three-dimensional finite-difference time-domain method, we demonstrate that the DM-SPCNC (AM-SPCNC) simultaneously possesses

A study of positron capture in a two-(pressure) stage buffer gas accumulation apparatus is presented for a variety of species, including some molecules which are known to be either efficient for positron trapping, or are frequently used to cool the particles when held in these devices. Absolute accumulation efficiencies are reported for all species. A detailed optimisation procedure, which has identified

We present a robust, three-stage optical parametric amplifier driven by a Ti:Sapphire ultrafast laser system that implements passive carrier-envelope phase stabilization and directly generates five-cycle mid-IR pulses by dispersion compensation. The source is based on potassium titanyl arsenate crystals and exploits intra-pulse difference-frequency seed generation in the mid-IR. This source will be

We present an analytical method involving the nonlinear polarizability tensor for calculating the second harmonic generation (SHG) intensity for a nonlinear sandwich metasurface. The theoretical model is that a nonlinear meta-atom can be considered as a nonlinear electric- and magnetic-dipole, which allows the nonlinear polarizability tensors to be calculated from the far-field of the scattered SHG

We present various types of reduced models including five vibrational modes and three electronic states for the pyrazine molecule in order to investigate the lifetime of electronic coherence in a rigid and neutral system. Using ultrafast optical pumping in the ground state (1 1 A g ), we prepare a coherent superposition of two bright excited states, 1 1 B 2u and 1 1 B 1u , and reveal the effect of

We simulated the multielectron dynamics of a CO molecule irradiated by near-IR λ = 760 nm two-cycle pulses with different carrier envelope phases by using the multiconfiguration time-dependent (TD) Hartree–Fock (MCTDHF) method. The ionization rate estimated from the simulations is higher when the laser electric field ɛ ( t ) points from C to O than in the opposite case, in agreement with the results

This paper computationally investigates the effect of the polarization decay rate ( γ ), and the peak resonance frequency ( f 0 ) on optical parametric amplification inside a low-loss micro resonator. It is found that, for lower values of the polarization decay rate and the peak resonance frequency, the magnitude of amplification can be significantly higher. However, it was also observed that beyond

We study the system consisted of two electrons in a quantum dot with a three-dimensional harmonic confinement potential under the effect of a magnetic field. Specifically, two different confinement conditions are considered, one isotropic three-dimensional and the other anisotropic quasi-two-dimensional. Singlet and triplet lowest states properties as the energy, the exchange coupling, the two-electron

We apply a spectrally-resolved electron interferometry technique to the measurement of the spectral phase in the vicinity of the 3s 1 3p 6 4p Fano resonance of argon. We show that it allows disentangling the phases of the two nearly-overlapping electron wavepackets corresponding to different spin–orbit final states. Using simple assumptions, it is possible to process the experimental data and numerically

Interatomic coulombic decay (ICD) in van der Waals endohedral complexes was predicted to be anomalously fast. However, the available theoretical calculations of the ICD rates in endohedral complexes only consider the equilibrium geometry, in which the encapsulated atom is located at the centre of the fullerene cage. Here we show analytically that the dominant contribution of the dipole plasmon resonance

We review methods for coherently controlling Rydberg quantum states of atomic ensembles using adiabatic rapid passage and stimulated Raman adiabatic passage. These methods are commonly used for population inversion in simple two-level and three-level systems. We show that adiabatic techniques allow us to control population and phase dynamics of complex entangled states of mesoscopic atomic ensembles

Ultra-short extreme ultraviolet pulses from the free-electron laser FLASH are characterized using terahertz-field driven streaking. Measurements at different ultra-short extreme ultraviolet wavelengths and pulse durations as well as numerical simulations were performed to explore the application range and accuracy of the method. For the simulation of streaking, a standard classical approach is used

Quantum steering in a system consisting of a qubit coupled to a single-mode field are explored when classical-like measurements implemented by heterodyne detection schemes that collapse the state of the field on to a coherent state are considered with the aim of constructing the generalized quantum steering ellipsoid for the qubit. The steering ellipsoid of the qubit enables visualization of the set

The oscillator strengths and integral cross sections of the valence-shell excitations of SO 2 have been determined at an incident electron energy of 1.5 keV and an energy resolution of about 70 meV, which are of great importance for modeling the planet’s atmospheric phenomena and astronomical observations. By comparing the present results with the previous electron scattering ones, it is found that

An analytical global potential energy surface for the ground electronic state of SSiH is here reported. The function is based upon ab initio energies calculated at Davidson-corrected multi-reference configuration interaction level with the aug-cc-pV(T + d)Z and aug-cc-pV (Q + d)Z basis sets and subsequently extrapolated to the complete basis set (CBS) limit. The analytical representation follows the

Two-modes (symmetric–asymmetric) reduction of the CO 2 vibrational kinetics has been introduced systematically for the purpose of state-to-state modeling. The two-modes approach is known from multi-temperature models. Its basic assumption is that vibrational energy of the CO 2 molecule which depends on 4 quantum numbers can be approximated by a function of only 2 numbers. Subsequently, vibrational

The electronic structure of the quasi-two-dimensional disk-like artificial atom involving holes inside has been studied by the full configuration interaction (FCI) wave function employing mixed basis sets consisting of standard atomic orbitals and anisotropic Gaussian-type functions. The one-particle confinement potential for electrons has been modeled by a sum of an anisotropic harmonic-oscillator

We investigate scaling rules for the ionization cross sections of multicharged ions on molecules of biological interest. The cross sections are obtained using a methodology presented by Mendez et al (2020 J. Phys. B: At. Mol. Opt. Phys. 53 055201), which considers distorted-wave calculations for atomic targets combined with a molecular stoichiometric model. We examine ions with nuclear charges Z from

The 3p 43 P J –3p 3 4p 3 P J transition in the sulphur atom is investigated in a precision two-photon excitation scheme under Doppler-free and collision-free circumstances yielding an absolute accuracy of 0.0009 cm −1 , using a narrowband pulsed laser. This verifies and improves the level separations between amply studied odd parity levels with even parity levels in S I. An improved value for the 3

It is known that being pumped with infrared light an ensemble of Rb atoms can demonstrate an upconversion and re-emit blue light at 420 nm. In pulsed regime this radiation can be enhanced by collective effects, which is called yoked superradiance. Here we demonstrate that not only the blue-light emission is affected by collective effects, but also the red light scattering. This becomes possible due

Electron impact excitation of Ge-like (Xe 22+ ) to Cu-like (Xe 25+ ) highly charged xenon ions are studied and dipole allowed fine-structure transitions in the wavelength range 9–25 nm are considered. We use relativistic distorted wave method to calculate the electron excitation cross sections for the different transitions of the four ions in the scattered electron energy range from excitation threshold

Differential scattering cross sections for electron excitation of the three lowest excited electron states of carbon monoxide are obtained experimentally using low-energy electron energy-loss spectroscopy and theoretically using the R -matrix method. The incident electron energies range from near-threshold of 6.3 eV to 20 eV. Experimental scattering angles range from 20° to 120°. The normalization

Despite the wide employment of transient absorption spectroscopy in capturing fast-evolving dynamics, the experiments lack further exploration of macroscopic effects beyond the single-atom response. Here, the absorbance of Rb atoms excited and coupled by two near-infrared pulses with a variable interpulse delay is studied both experimentally and theoretically, from the limit of a dilute-gas medium

We observed the dynamical evolution of the electron–nuclear wavepacket composed of the ##IMG## [http://ej.iop.org/images/0953-4075/53/16/164001/bab94ccieqn2.gif] {${B}^{2}{{\Sigma}}_{\text{g}}^{-}$} and 3 2 Π u states of ##IMG## [http://ej.iop.org/images/0953-4075/53/16/164001/bab94ccieqn3.gif] {${\mathrm{O}}_{2}^{+}$} with an evolution period of 1.3 fs. We created a dissociative wavepacket of ##IMG##

Using quantum-mechanical, one-dimensional, non-Born–Oppenheimer simulations we study the control over the strong-field dynamics of the helium hydride molecular ion HeH + due to interaction driven by short and strong two-color laser pulses. We calculate yields of two competing fragmentation channels: electron removal and dissociation. We find that by changing the relative phase of the two colors, we

In this work we investigate the interaction of aniline in the gas phase with 50 fs pulses of radiation at a wavelength of 800 nm. Ion yields were measured using a reflectron time-of-flight mass spectrometer that avoids spatial averaging by collecting ion from a micrometer-sized volume within the focal region. This measuring technique allows for accurate measurements and quantification of relative ion

##IMG## [http://ej.iop.org/images/0953-4075/53/17/174002/bab9999ieqn1.gif] {${\mathrm{H}}_{2}^{+}$} exposed to strong mid-infrared laser pulses undergoes the tunneling ionization, followed by the rescattering of the photoelectron with the parent ion. The two nuclei repel each other during the tunneling and rescattering, which modifies the Coulomb potential experienced by the rescattering electron.

In a strong electric field, a dipolar molecule will contract or expand and, in extreme cases, dissociate. Considering a two-atomic non-rigid dipole described by the realistic Kratzer model, we compute analytical energy corrections up to fourth order in the field strength for general states and ninth order for the ground state. The fourth-order series is subsequently ‘resummed’ using the hypergeometric

We report on a measurement of several n = 3 → n = 2 inner-shell transitions in sodiumlike, magnesiumlike, and aluminumlike europium, performed at the EBIT-I electron beam ion trap facility at the Lawrence Livermore National Laboratory using an x-ray calorimeter. Although the inner-shell x-ray lines of such M-shell ions are typically dominated by electric dipole allowed transitions, we have also identified

We consider a two-dimensional self-bound quantum droplet, which consists of a mixture of two Bose–Einstein condensates. We start with the ground state and then turn to the rotational response of this system, in the presence of an external (harmonic) potential. We identify various phases, depending on the atom number, the strength of the external confinement and the angular momentum. These include center

The amount of ionization produced in a laser-matter interaction provides critical information in studying strong field physics and attosecond science. The amount of ionization can be accurately measured in vacuum using a photoelectron/ion spectrometer by counting the number of charged particles. However, an ionization yield measurement in ambient air requires the considerations of post processes such

Recently, we have demonstrated (Jin et al 2020 J. Phys. B: At. Mol. Opt. Phys. 53 075201) that a hybrid subconfiguration-average and level-to-level distorted wave treatment of electron-impact single ionisation (EISI) of W 14+ ions represents an accurate and manageable approach for the calculation of EISI cross sections of a complex ion. Here we demonstrate the more general validity of this approach

Nonclassicality of a single-mode state can be quantified by the entanglement (potential) the state creates at the output of a beam splitter. Thus, beam splitter transformation can be utilized for obtaining single-mode nonclassicality conditions (quantifications) from two-mode entanglement criteria (measures). Here, (i) we employ this relation to quantify the single-mode nonclassicality (SMNc) of a

An extreme-ultraviolet (XUV) laser pulse consisting of harmonics of a fundamental near-infrared (NIR) laser frequency is combined with the NIR pulse to systematically study two-color photoionization of helium atoms. A time-resolved photoelectron spectroscopy experiment is carried out where energy- and angle-resolved photoelectron distributions are obtained as a function of the NIR intensity and wavelength

Over the past few years it has been pointed out that direct inversion of accurate but approximate ground state densities leads to Kohn–Sham exchange–correlation (xc) potentials that can differ significantly from the exact xc potential of a given system. On the other hand, the corresponding wavefunction based construction of exchange-correlation potential as done by Baerends et al and Staroverov et

In this paper, we discuss temporal optical phenomena in a gas of Rydberg atoms, which can take place in the presence of varying quasi-static electric fields and control laser beams. This includes the discussion of spectral changes of probe laser beams, associated with purely temporal processes created by Stark and ac-Stark shifts of the atomic susceptibility. Such changes include phase and group velocity

We have investigated the double ionization of helium induced by 45 fs, 394 nm linearly polarized laser pulses for intensities (2.5–150) × 10 14 W cm −2 . The time evolution of the process was determined by applying the classical ensemble approximation (CEA) model. The results of the calculations obtained for the double-to-single ionization ratio, the momentum distribution of the He 2+ recoil ion and

We study an impurity immersed in the mixture of Bose ultracold gases in the regime where a quantum droplet (QD) exists. The quasi-one-dimensional geometry is considered. We find an effective attractive potential, which acts by the QD onto the impurity. The bound states of the impurity in this potential are investigated. These impurity-bound states can provide potential probes for the presence of quantum

For a molecule irradiated by an intense laser field, the sudden excitation or removal of an electron will trigger ultrafast electronic and nuclear dynamics, of which the timescales are usually several orders different and can be separately treated according to the Born–Oppenheimer approximation. However, the electrons and nuclei are intrinsically coupled in a molecule and should be considered on an

Attosecond pulses can be used to generate coherent superpositions of cationic electronic states in molecules through photoionisation. These can drive coherent electronic dynamics, which may decay within a few femtoseconds due to nuclear motion. In this work, we study the impact of the photoelectron on decoherence in the valence electron system of molecules following attosecond photoionisation. To this

Transient absorption is a very powerful observable in attosecond experiments on atoms, molecules and solids and is frequently used in experiments employing phase-locked few-cycle infrared and XUV laser pulses derived from high harmonic generation. We show numerically and analytically that in non-centrosymmetric systems, such as many polyatomic molecules, which-way interference enabled by the lack of

The numerical propagation of intense laser pulses through bulk material requires the recurrent calculation of the nonlinear material response. To describe the optical Kerr effect and the current in the conduction band for macroscopic propagation distances, very simplified models are typically used. Recent studies of the response of dielectrics to intense few-cycle pulses have revealed that ionization

In strong-field ionization, the combined influence of nondipole and Coulomb focusing effects leave a unique signature on the photoelectron momentum distributions, which may have direct implications on many important strong-field phenomena. We present a comprehensive review of the experimental and theoretical investigations on these effects. We classify these investigations by relativistic and non-relativistic

We generate attosecond pulse train (APT) in argon driven by the high repetition rate (HR) laser of the extreme light infrastructure-attosecond light pulse source (ELI-ALPS), providing 100 kHz, 80 W, 1030 nm, 40 fs pulses from a fiber chirped-pulse amplification (fiber-CPA) laser system. Under the current operating conditions of the high harmonic generation beamline (HR-GHHG), we observed the average

The nonclassical feature of photons in the open finite-size Dicke model is investigated via the two-photon correlation function. The quantum dressed master equation combined with the extended coherent photonic states is applied to analyze the dissipative dynamics of both the photons and qubits. The antibunching to bunching transition of photons is clearly observed by tuning the qubit–photon coupling

We propose a modified version for the strong field theory of high-order harmonic generation (HHG) in molecules and we apply it to analyze the orientation-dependences of HHG from the hydrogen molecule and it molecular ion H 2 + when exposed to linearly polarized laser light. Our model predicts the presence of clear interference minima in the spectra of the high-order harmonics. We further exploit the

This paper studies sum sideband generation in a parity-time ( ##IMG## [http://ej.iop.org/images/0953-4075/53/15/155403/bab8e54ieqn1.gif] {$\mathcal{PT}$} )-symmetric optomechanical system, where an active cavity is coupled to the passive cavity of a general optomechanical system. We find that the upper and lower sum sideband generation efficiencies can be greatly enhanced by the introduction of the

We propose methods for the realization of a continuous two-photon source using a coherently driven quantum dot embedded inside a photonic crystal cavity. We analyze the steady state population in quantum dot energy levels and field inside the cavity mode. We find conditions for population inversion in coherently driven and incoherently driven quantum dots. We discuss the effect of phonon coupling using

We report on a combined experimental and theoretical study of XUV ionization of atomic argon in the presence of a near-infrared (NIR) laser field. Using a table-top source of wavelength-selected femtosecond XUV pulses in combination with a velocity map imaging spectrometer we record angle- and energy-resolved photoelectron distributions and simulate the experimental data by solving the time-dependent

We provide a short response to Buică’s comment on our paper ‘Two-photon laser-assisted electron scattering on hydrogen atom’ (Kornev and Zon 2019 J. Phys. B: At. Mol. Opt. Phys. 52 075205). The reply explains some of the points mentioned in the comment.

The photoabsorption and photoionization dynamics of the I 4d and valence orbitals in methyl iodide have been studied both experimentally and theoretically. Synchrotron radiation has been employed to measure the total ion yield in the vicinity of the I 4d ionization thresholds. The observed structure, due to excitations into Rydberg or valence states, has been assigned using transition energies and

We propose a versatile scheme for multiphoton frequency up/down conversion in flux superconducting qubit circuits, driven by a pair of microwaves tuned near and far off the qubit resonance. Flux qubits can be engineered with strong anharmonicity such that the two lowest eigenstates are energetically well separated from the higher ones. We demonstrate the high order non-linear transitions between the

Dissociative excitation of methanol (CH 3 OH) by electron impact leading to the production of O( 1 S) and CO(a 3 Π) has been studied in the energy range from threshold to 100 eV using a unique detector which is selectively sensitive to low energy metastable particles. Time of flight techniques are used to separate atomic and molecular fragment species. Energy considerations have allowed certain excitation

In this work, the normal density ρ n and moment of inertia of a moving superfluid are investigated. We find that, even at zero temperature, there exists a finite normal density for the moving superfluid. When the velocity of superfluid reaches sound velocity, the normal density becomes total mass density ρ , which indicates that the system losses superfluidity. At the same time, the Landau’s critical

The ultimate challenge for shaping technology is how to control the light field with a single optical element in a high-speed manner, wherein the spatial distribution of amplitude, phase or polarization are manipulated. Here we describe the use of the magneto optic effect to achieve the rapidly shaping of vector beams in real time using atomic ensemble. Firstly, the Faraday-rotation effect of vector

We theoretically explore optical bistability for the possible signature of all-optical switching and their performance in a hybrid quantum optomechanical system comprising of two semiconductor microcavities coupled optically. One of the cavity is driven by an external amplitude-modulated pump laser while the second cavity, which contains a quantum dot (QD), is indirectly driven by light transmitted