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Динамика амплитуд вероятности в водородоподобном атоме под действием сильного переменного электрического поля электромагнитной волны с учетом переходов в континуум

Maria V. Ryabinina, Leonid A. Melnikov

Published Jan 1, 2008• 0 citations
OpenAlex

Abstract

The dynamics of populations of 4s and 3p states in hydrogen atom is investigated under the action of ultra high laser single frequency linear-polarized pulse at one-, twoand three-photon resonance and at large detuning out of frame of perturbation theory and rotating wave approximation. It was shown the existence of low frequency modulation of optical oscillations,which frequency becomes zero at some values of laser field amplitude. For the transition 3s ^ 2p the population dynamics of discrete states 3s and 2p is investigated, and also of the states in continuum which are bounded with the state 3s via optical transition. Coherent-like oscillations of the population of the states in continuum are demonstrated.

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Динамика заселенностей уровней и поляризации при двухфотонном резонансном переходе 1s-2s в атоме водорода (антиводорода) в поле фемтосекундного лазерного импульса

Maria V. Ryabinina, Leonid A. Melnikov

The dynamics of two-photon 1s↔2s transition in (anti)hydrogen atom in the field of femtosecond linearly polarized standing wave laser pulse is investigated. The density matrix equations for three levels 1s, 2s, and 2p were solved numerically out of frames of rotating wave approximation and perturbation approach. The coherent Rabi oscillation at different spatial points, velocity effect on level populations, saturation behavior of 2p-level population, and spectra of multiphoton resonances are demonstrated.

Вестник Саратовского государственного технического университета•Jan 1, 2014•0 citations

Coherent effects in free-bound transitions in hydrogen/antihydrogen atom under the action of ultra-short strong-field laser pulse

Maria V. Ryabinina, Leonid A. Melnikov

Using discrete approximation of the continuous levels in H-atom the nonperturbative probability amplitude equations for 1s state and groups of continuous levels coupled via laser resonant pulse were solved numerically. The coherent Rabi-like population oscillations of 1s -state are observed. The role of free-free transitions, optimum pulse area and other parameters for recombination are discussed.

Proceedings of SPIE, the International Society for Optical Engineering/Proceedings of SPIE•Jun 21, 2007•0 citations

Решетки населенностей, создаваемые в газе атомов водорода с помощью ультрафиолетовых аттосекундных импульсов

Р. М. Архипов, М.В. Архипов, А.В. Пахомов +2 more

The possibility of population density grating in a gas of hydrogen atoms using a pair ultraviolet (UV) attosecond pulses that do not overlap in the medium is studied. Wherein the central frequency of the pulses can both coincide with the frequency of the resonant transition 1−2 from the main state in the first excited state (the main line of the Lyman series), and be detuned from it. The results of numerical calculations are in agreement with the analytical values ​​obtained on the basis of approximate solution of Schrödinger equation using perturbation theory. It is shown that under resonant excitation the greatest efficiency of the grating is achieved with an increase in the pulse duration. When nonresonant excitation, on the contrary, the system is more efficiently excited by short quasi-unipolar subcycle pulses than bipolar multicycle pulses. The results obtained can be applicable to coherent excitation of a single atom (thin layer) using a pair of UV pulses. The possibility of controlling the modulation depth of the gratings by changing the carrier envelope phase (CEP) of attosecond pulses is shown.

Оптика и спектроскопия•Jan 1, 2021•1 citation

Low-frequency strong-field ionization and excitation of hydrogen atom

A. M. Popov, Olga V. Tikhonova, Ekaterina A. Volkova

The dynamics of hydrogen atom in the presence of a strong radiation field of the titanium-sapphire laser is studied for the Keldysh parameters γ ≥ 1 and γ ≤ 1. It is demonstrated that the ionization is supplemented with the effective population of the excited states with the principal quantum numbers n = 5–10 in the entire range of variation in the Keldysh parameter. The population of the excited Rydberg states can be interpreted as a consequence of the multiphoton resonance involving the initial 1 s state and a group of excited states in the vicinity of the continuum boundary with the simultaneous repopulation of these states by Λ-type Raman transitions under the action of the laser field. The resulting coherent Rydberg packet appears to be stable with respect to ionization, so that the ionization of the atomic system in the presence of strong electromagnetic field is suppressed. Physical reasons for the stabilization are discussed. An interpretation of the effective population of the Rydberg states in the recent experiments on the ionization of atomic helium by the titanium-sapphire laser is proposed.

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Dynamics of population of a four-level atom due to one- and three-photon processes

M. P. Sharma, José Antonio Roversi

The Schr\"odinger equation in the rotating-wave approximation has been solved nonperturbatively to study the temporal behavior of the occupation probabilities of different levels of a four-level atom interacting with four arbitrarily intense laser fields, such that the frequency of one of them equals the sum of the other three. The three-photon-excitation population dynamics, which is already complex, is strongly modified by one-photon excitation and detunings. Under certain conditions the three-photon excitation traps the population in the state initially populated; the population starts flowing into other states when one-photon excitation is also operative.

Physical Review A•Jun 1, 1984•13 citations

Динамика экситонных переходов в полупроводниковых наноструктурах с квантовыми точками

Русецкий Григорий Александрович, Oleg Kh Khasanov

The work deals with the influence of local field effects on the dynamics of exciton transitions in semiconductor structures with quantum dots. It is shown that in the field of ultrashort light pulse the dynamic frequency shift leads to the realization of oscillations of four types including bifurcational mode. The Rabi oscillations in the field of long pulse, when the phase relaxation effect becomes substantial, are analyzed. It is shown that in this case three modes of oscillations are realized. In addition, the transition from one oscillation frequency to another is observed. The moment of transition is determined by the phase relaxation rate and the value of its nonlinearity.

Ученые записки Казанского университета. Серия Физико-математические науки•Jan 1, 2010•0 citations
The dynamics of populations of 4s and 3p states in hydrogen atom is investigated under the action of ultra high laser single frequency linear-polarized pulse at one-, twoand three-photon resonance and at large detuning out of frame of perturbation theory and rotating wave approximation. It was shown the existence of low frequency modulation of optical oscillations,which frequency becomes zero at some values of laser field amplitude. For the transition 3s ^ 2p the population dynamics of discrete states 3s and 2p is investigated, and also of the states in continuum which are bounded with the state 3s via optical transition. Coherent-like oscillations of the population of the states in continuum are demonstrated.
The dynamics of two-photon 1s↔2s transition in (anti)hydrogen atom in the field of femtosecond linearly polarized standing wave laser pulse is investigated. The density matrix equations for three levels 1s, 2s, and 2p were solved numerically out of frames of rotating wave approximation and perturbation approach. The coherent Rabi oscillation at different spatial points, velocity effect on level populations, saturation behavior of 2p-level population, and spectra of multiphoton resonances are demonstrated.
The possibility of population density grating in a gas of hydrogen atoms using a pair ultraviolet (UV) attosecond pulses that do not overlap in the medium is studied. Wherein the central frequency of the pulses can both coincide with the frequency of the resonant transition 1−2 from the main state in the first excited state (the main line of the Lyman series), and be detuned from it. The results of numerical calculations are in agreement with the analytical values ​​obtained on the basis of approximate solution of Schrödinger equation using perturbation theory. It is shown that under resonant excitation the greatest efficiency of the grating is achieved with an increase in the pulse duration. When nonresonant excitation, on the contrary, the system is more efficiently excited by short quasi-unipolar subcycle pulses than bipolar multicycle pulses. The results obtained can be applicable to coherent excitation of a single atom (thin layer) using a pair of UV pulses. The possibility of controlling the modulation depth of the gratings by changing the carrier envelope phase (CEP) of attosecond pulses is shown.
The dynamics of hydrogen atom in the presence of a strong radiation field of the titanium-sapphire laser is studied for the Keldysh parameters γ ≥ 1 and γ ≤ 1. It is demonstrated that the ionization is supplemented with the effective population of the excited states with the principal quantum numbers n = 5–10 in the entire range of variation in the Keldysh parameter. The population of the excited Rydberg states can be interpreted as a consequence of the multiphoton resonance involving the initial 1 s state and a group of excited states in the vicinity of the continuum boundary with the simultaneous repopulation of these states by Λ-type Raman transitions under the action of the laser field. The resulting coherent Rydberg packet appears to be stable with respect to ionization, so that the ionization of the atomic system in the presence of strong electromagnetic field is suppressed. Physical reasons for the stabilization are discussed. An interpretation of the effective population of the Rydberg states in the recent experiments on the ionization of atomic helium by the titanium-sapphire laser is proposed.
The Schr\"odinger equation in the rotating-wave approximation has been solved nonperturbatively to study the temporal behavior of the occupation probabilities of different levels of a four-level atom interacting with four arbitrarily intense laser fields, such that the frequency of one of them equals the sum of the other three. The three-photon-excitation population dynamics, which is already complex, is strongly modified by one-photon excitation and detunings. Under certain conditions the three-photon excitation traps the population in the state initially populated; the population starts flowing into other states when one-photon excitation is also operative.
The work deals with the influence of local field effects on the dynamics of exciton transitions in semiconductor structures with quantum dots. It is shown that in the field of ultrashort light pulse the dynamic frequency shift leads to the realization of oscillations of four types including bifurcational mode. The Rabi oscillations in the field of long pulse, when the phase relaxation effect becomes substantial, are analyzed. It is shown that in this case three modes of oscillations are realized. In addition, the transition from one oscillation frequency to another is observed. The moment of transition is determined by the phase relaxation rate and the value of its nonlinearity.