Challenges
Datasets
Workspaces
Papers
Discussions
Leaderboard
Log inSign up
Challenges
Datasets
Workspaces
Papers
Discussions
Leaderboard
Blog
Job Board
Q3AS

© 2026 Aqora Quantum S.A.S.

TermsPrivacyLegal Notice

Journal of Experimental and Theoretical Physics

Landau-Dykhne approximation for multiphoton dipole-forbidden transitions

B. A. Zon, A. S. Kornev

Published Jun 1, 2007• 1 citation
Publisher

Abstract

A two-level system in a monochromatic laser field is considered in the Landau-Dykhne approximation under the violation of dipole selection rules. An analytic expression is obtained for the rate of transitions. The multiphoton and tunneling limits are found.
DOI
10.1134/s1063776107060027

Related papers

Effect of resonance mixing of states of a three-level system on the emergence of multiphoton transitions from them

І. І. Бондар, В. В. Суран

It is established experimentally for the first time that multiphoton transitions, which are forbidden by the parity selection rules in the dipole approximation, occur from resonantly mixed states in a three-level system with probabilities approximately equal to the probabilities of multiphoton transitions that are allowed by such selection rules.

Quantum Electronics•Jul 31, 2002•0 citations

Permanent dipole moments and two-color multiphoton resonances in the two-level molecule: The rotating wave approximation versus exact results

A. E. Kondo, V. M. Blokker, William J. Meath

The interaction of two continuous wave electric fields (lasers) with a two-level molecule, that has a nonzero difference d, between the permanent dipoles of the two states involved in a multiphoton two-color transition, is studied in the rotating wave approximation and by using exact methods. Analytical rotating wave approximation results for the time-dependent populations of the molecular states and for the resonance profiles are derived and used to help discuss the effects of permanent dipole moments in the two-color absorption problem. Several examples of multiphoton, two-color, two-level resonance profiles calculated in the rotating wave approximation and by using exact techniques, are employed for illustrative purposes. They are used to help quantify the conditions for the validity of the two-color rotating wave approximation, which are considerably more restrictive than the analogous conditions for the one-color rotating wave approximation with d≠0, and to illustrate the interpretive and predictive nature of the rotating wave approximation results. For example, there are many multiphoton, two-color transitions that are available if a molecule possesses permanent dipoles (d≠0). The analytic rotating wave approximation expression for the molecule-two laser coupling can often be used to reliably estimate the field parameters of the two lasers that are required to optimize a given transition relative to others.

The Journal of Chemical Physics•Feb 15, 1992•30 citations

Interaction of non-monochromatic laser field with two-level atom

V. O. Chaltykyan, G. G. Grigoryan, Y. Pashayan-Leroy

The problem of a two-level atom interacting with a non-monochromatic radiation pulse is studied in the resonant approximation for arbitrary detunings, and without the resonant approximation. By using the time-dependent theory of perturbation the analytical expressions for the transition probability and induced dipole moment of the atom are obtained. It is shown that the upper level population of the atom exhibits oscillations that are absent in the resonant approximation. The temporal shape of the pulse is shown to affect significantly the atomic transition probability. The behaviour of the transition probability and dipole moment spectrum for arbitrary pulse shapes, phases and detunings is investigated. The interference between the spectral components arising in nonlinear processes is shown to play a considerable role in the formation of a dipole moment spectrum.

Journal of Modern Optics•Jan 1, 2000•5 citations

Coherent radiation by two-level quantum systems with permanent dipole moments under multiphoton resonant laser excitation

H. K. Avetissian, B. R. Avchyan, G. F. Mkrtchian

The theory of coherent radiation emission in two-level quantum systems with permanent dipole moments at the multiphoton resonant excitation by moderately strong laser fields is presented. A simple analytic formula for the expectation value of a dipole moment operator is obtained. The spectrum corresponding to harmonic generation and low-frequency radiation on the generalized Rabi frequency is investigated both analytically and numerically. The effect of dynamic Stark shift on a dipole spectrum under direct multiphoton resonant excitation is considered.

Journal of Physics B Atomic Molecular and Optical Physics•Dec 19, 2011•20 citations

Two-level system in a strong laser field: A comparative analysis between the Landau-Lifshitz solution and an exact numerical one

Raanan Bavli, Yuri I. Dakhnovskii

We numerically solve the problem of a two-level system in a near-resonance time-dependent electric field of arbitrary amplitude. The obtained radiation spectrum of the dipole moment is compared both to that of a Landau-Lifshitz (LL) textbook solution [Quantum Mechanics (Pergamon, New York, 1987), p. 145] and to an off-resonance analytical solution [Dakhnovskii and Bavli (unpublished)] obtained recently for both optical and tunneling initial conditions. We show that the LL solution is valid at low field intensities while the off-resonance analytic solution qualitatively describes the intermediate- and high-intensity regimes.

Physical Review A•Aug 1, 1993•9 citations

Multiphoton quantum interference on a dipole-forbidden transition

Uzma Akram, Jörg Evers, Christoph H. Keitel

We investigate the effect of an intense low-frequency field on the population decay of an excited two-level atom, where the two states are connected by a dipole-forbidden transition. In addition to the natural two-photon spontaneous decay, the low-frequency field gives rise to induced two-photon processes, where one of the two photons is spontaneous. Due to the low frequency of the applied field, the induced decay pathways may interfere with each other. We show how varying the parameters of the applied field allows switching between constructive and destructive interference, thereby increasing or decreasing the induced transition rate as compared to the rate without interference. As all relevant competing transitions are of the same multiphoton order, the system is a promising candidate to verify the idea of spontaneous-emission interference induced by multiphoton pathways experimentally.

Journal of Physics B Atomic Molecular and Optical Physics•Feb 8, 2005•6 citations
The interaction of two continuous wave electric fields (lasers) with a two-level molecule, that has a nonzero difference d, between the permanent dipoles of the two states involved in a multiphoton two-color transition, is studied in the rotating wave approximation and by using exact methods. Analytical rotating wave approximation results for the time-dependent populations of the molecular states and for the resonance profiles are derived and used to help discuss the effects of permanent dipole moments in the two-color absorption problem. Several examples of multiphoton, two-color, two-level resonance profiles calculated in the rotating wave approximation and by using exact techniques, are employed for illustrative purposes. They are used to help quantify the conditions for the validity of the two-color rotating wave approximation, which are considerably more restrictive than the analogous conditions for the one-color rotating wave approximation with d≠0, and to illustrate the interpretive and predictive nature of the rotating wave approximation results. For example, there are many multiphoton, two-color transitions that are available if a molecule possesses permanent dipoles (d≠0). The analytic rotating wave approximation expression for the molecule-two laser coupling can often be used to reliably estimate the field parameters of the two lasers that are required to optimize a given transition relative to others.
The problem of a two-level atom interacting with a non-monochromatic radiation pulse is studied in the resonant approximation for arbitrary detunings, and without the resonant approximation. By using the time-dependent theory of perturbation the analytical expressions for the transition probability and induced dipole moment of the atom are obtained. It is shown that the upper level population of the atom exhibits oscillations that are absent in the resonant approximation. The temporal shape of the pulse is shown to affect significantly the atomic transition probability. The behaviour of the transition probability and dipole moment spectrum for arbitrary pulse shapes, phases and detunings is investigated. The interference between the spectral components arising in nonlinear processes is shown to play a considerable role in the formation of a dipole moment spectrum.
The theory of coherent radiation emission in two-level quantum systems with permanent dipole moments at the multiphoton resonant excitation by moderately strong laser fields is presented. A simple analytic formula for the expectation value of a dipole moment operator is obtained. The spectrum corresponding to harmonic generation and low-frequency radiation on the generalized Rabi frequency is investigated both analytically and numerically. The effect of dynamic Stark shift on a dipole spectrum under direct multiphoton resonant excitation is considered.
We numerically solve the problem of a two-level system in a near-resonance time-dependent electric field of arbitrary amplitude. The obtained radiation spectrum of the dipole moment is compared both to that of a Landau-Lifshitz (LL) textbook solution [Quantum Mechanics (Pergamon, New York, 1987), p. 145] and to an off-resonance analytical solution [Dakhnovskii and Bavli (unpublished)] obtained recently for both optical and tunneling initial conditions. We show that the LL solution is valid at low field intensities while the off-resonance analytic solution qualitatively describes the intermediate- and high-intensity regimes.
We investigate the effect of an intense low-frequency field on the population decay of an excited two-level atom, where the two states are connected by a dipole-forbidden transition. In addition to the natural two-photon spontaneous decay, the low-frequency field gives rise to induced two-photon processes, where one of the two photons is spontaneous. Due to the low frequency of the applied field, the induced decay pathways may interfere with each other. We show how varying the parameters of the applied field allows switching between constructive and destructive interference, thereby increasing or decreasing the induced transition rate as compared to the rate without interference. As all relevant competing transitions are of the same multiphoton order, the system is a promising candidate to verify the idea of spontaneous-emission interference induced by multiphoton pathways experimentally.