The quantum-mechanical amplitude for the transition from an initial state i to a final state f can be represented in terms of Feynman’s path integral. This integral includes all histories of the transition i -> f, i.e. the sum over all paths in space with fixed end points. In the classical limit this sum reduces to a sum over all classical paths for which the action S is stationary. In quantum...

The research topic is calculation of the drift velocity of electron transport in $N_2$ gas under the influence of an external crossed electromagnetic field, E x B. A Monte Carlo simulation code has been used to obtain non-equilibrium electron energy distribution function within one oscillation of external crossed fields. In simulation, E is aligned with the z-axis, while B is parallel with...

We are reporting the results of the first experimental determination of the collision-energy dependence of the muon transfer rate from the ground state of muonic hydrogen to oxygen in the energy range below 100 meV. These results shed new light on the kinematics of the processes involving exotic atoms, and may serve as benchmark for the full-scale quantum-mechanical calculations of low-energy...

Muonium formation in muon-hydrogen ($\mu^+-\rm{H}(1s^1)$) and muon-helium ($\mu^+-\rm{He}(1s^2)$) charge-exchange collisions is considered at intermediate and high impact energies, from 10 keV to 1 MeV. The prior form of the three-body boundary-corrected first Born approximation (CB1-3B) [1] is used for calculations of the state-selective total cross sections $Q_{nl}$ for single-electron...

Precise spectroscopy of light atomic and molecular systems gives us new insides in the fundamental laws and physical constants of nature [1]. In particular, exotic atoms like antihydrogen and antiprotonic helium could also allow comparison between matter and antimatter characteristics and test of CPT symmetry [2]. From theoretical point of view, development of very accurate techniques like...

Harmonium is a system of two electrons whose Coulomb interaction with the nucleus is replaced with harmonic potential. Such a theoretical system is widely used for studying density functional theory, electron correlation, entanglement and black body entropy. It is of great importance to examine spherically confined harmonium in plasma environment, since the results can be useful for...

Fitting potential energy curves (PEC) for diatomic molecules becomes a well-established routine confirmed empirically with numerous examples in the literature. One of the questions, which remains still open concerns the extrapolation properties of the potential functions. The experimental PECs virtually always are determined from a limited set of experimental data and this in turns limits the...

Quantum computing (QC), based on principles of superposition, entanglement, and measurement of qubits, promises the advantage to surpass the performance of classical computing in cryptography, communication, and optimization problems, as well as in simulations of complex quantum system in physics and computation chemistry. Despite decades in development, fully coherent, fault-free universal...

In this talk I will review the very recent experiments conducted by my group on various quantum control techniques at some of the open-access IBM quantum processors. I particular, I will show results on quantum control by composite pulses, quantum control by polychromatic pulse trains, quantum sensing of small frequency shifts, tuning the parameters of the quantum computer, dynamical...

The recent discovery of the NS+ cation in the interstellar medium1 triggered the interest in the study of its collision with electrons. In this complex process, the electron can be captured into NS Rydberg-bound states predissociated by Feshbach resonances of this latter molecule. These both types of states have been calculated within the Born-Oppenheimer approximation using a variationa...

Non-sequential double ionization (NSDI) is a strong-field atomic process in which two electrons simultaneously leave atom irradiated by an intense laser pulse.$^1$ This process has been described successfully by the three-step (TS) model. The first step of this model is the process of tunneling an atomic electron through the barrier which is formed by combining the atomic potential with the...

Providing effective lubrication at high temperatures/pressures and in oxidative environments is relevant for various industrial applications, such as turbomachinery and cutting tools [1,2]. Promising solutions for such conditions are oxidation-resistant hard coatings consisting of binary or ternary films (Cr-N, Ti-N, Cr-Al-N, Ti-Al-N) doped with an additional element which can diffuse to the...