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

Physical Review A

Theory of resonance excitation of N -level atomic systems by strong coherent radiation

Yitzhak Rabin, A. Ben‐Reuven

Published Apr 1, 1979• 13 citations
Publisher

Abstract

Algebraic methods are developed for deriving steady-state solutions of the Bloch equations for a system of $N$ atomic (molecular) levels resonantly coupled to strong coherent radiation fields in the rotating-wave approximation, and undergoing thermal (radiative and collisional) homogeneous relaxation. These methods are applied to a "ladder" model, in which the excitation and relaxation occur by one-level steps, with one field mode in resonance with each step. Explicit solution (in terms of coupling strengths, relaxation rates, and frequency detunings) is given for the three-level system, and some observations are made on systems of four or more levels. The process of solution of the ${N}^{2}$-dimensional set of Bloch equations involves matrices of dimension $N\ensuremath{-}1$ or less.

DOI
10.1103/physreva.19.1697

Related papers

Theory of resonance scattering and absorption of strong coherent radiation by thermally relaxing multilevel atomic systems

A. Ben‐Reuven, Yitzhak Rabin

The resonant response of a multilevel atomic system to strong coherent radiation is analyzed using an extension of the methods of time-independent scattering theory, adapted to the density-matrix formalism in order to include thermal bath effects. General steady-state expressions are derived for self-attenuation and resonance scattering rates in strong saturating fields, as functions of the coupling strengths, relaxation parameters, and frequency detunings. Formal expressions are given for radiative-damping and collision-broadening relaxation parameters, relating the latter to scattering amplitudes. Modifications of collision-broadening parameters by the presence of very strong fields are discussed. The Bloch equations are derived by transformation to the time domain, under specified conditions.

Physical Review A•May 1, 1979•48 citations

Resonant absorption in stationary and nonstationary fields

V. Sethu Raman, Gerald J. Small

Response of a two-level atom, relaxing owing to strong thermalizing collisions, in a weak near-resonant pulsed radiation field is examined using the second order perturbation solution of the optical Bloch equations. Dependence of the rate of absorption on the collisional relaxation time of the atom, the correlation time, pulse width, and the degree of detuning of the incident field are discussed.

The Journal of Chemical Physics•Apr 15, 1976•2 citations

Nonlinear Resonance Effects in Multilevel Quantum Systems Weakly Coupled to a Thermal Reservoir

Clayton W. Bates

Calculations are made to determine the response (power absorbed, magnetization, etc.) of a multilevel quantum system under the influence of any number of classically described driving fields (well defined in amplitude and phase). A nonperturbative theory is developed to account for those fields that are in resonance with the system. The nonresonant effects, such as virtual energy shifts, are included in the theory. We limit ourselves to a discussion of quantum systems that are in weak contact with a thermal reservoir. The procedure is the following A projection-operator formalism is developed which separates the density matrix of a system into two parts. One part is related to those portions of the driving fields that interact quite strongly with the system. The other part is the nonresonant or weakly interacting portion. An exact equation of motion, which includes the effects of the nonresonant part, is derived for the strongly interacting part of the density matrix. It is then shown that when relaxation can be represented by phenomenological decay constants, a unitary transformation can be found which reduces the equation of motion for the strongly interacting part of the density matrix so that an exact solution is possible. This solution is shown to give the major effects of the driving fields and can be used as the zeroth-order solution in a perturbation treatment of the whole density matrix. Frequency shifts such as the Bloch-Siegert shift and shifts due to couplings between the levels of interest (resonance levels) and other levels (nonresonance levels) all arise in the same natural way in our treatment. Our results in many instances are the extensions of the well-known results for a two-level quantum-mechanical systemm to an $N$-level one, and include resonant multiple quantum effects. As an example, a straightforward application of the method is carried out in order to compute the shifts in the resonance frequencies of a four-level system, driven by two oscillating fields connecting three of the levels, due to the counter-rotating components of the driving fields and the presence of the fourth level, which is not coupled to the other levels by the driving fields.

Physical Review•Dec 10, 1969•6 citations

Coupled one- and two-photon resonances in three level atoms. [Averages method, density matrix]

J. C. Garrison, T. H. Einwohner, Jack Wong

The coherent excitation of a three level atom by one- and two-photon resonances coupled by a common level is treated by the method of averages. The equations for the density matrix of the three resonant levels are solved analytically for square pulses of duration shorter than relaxation times. Double free induction decay occuring when both exciting fields are switched out of resonance simultaneously is exhibited. The emitted radiation is also calculated for an experiment in which the field driving the one-photon resonance remains on after the other field ends, and it is shown that experiments at several detunings and amplitudes would allow determination of various combinations of relaxation rates. Numerical studies for nonsquare pulses are briefly described. The results show that the main qualitative features of the square-pulse case are retained. 15 references.

•Jun 1, 1979•0 citations

Thermal relaxation of adsorbed atoms in an intense laser field

Henk F. Arnoldus, Sander van Smaalen, Thomas F. George

Adsorbed atoms on the surface of a harmonic lattice are immersed in a strong laser field. The optical Bloch equations are derived, which include the thermal relaxation and the coherent excitation of the adbond. This is accomplished by a transformation to dressed states, which diagonalizes the interaction with the laser. The single-phonon couplings are then understood as transitions between dressed states. The radiative contributions for arbitrarily strong fields are obtained in the master equation, and it is shown that the coherences with respect to the dressed states decay exponentially, due to the phonon relaxation. General properties of the competing phonon-induced redistribution and optical excitation of the level populations are presented, and exemplified by an explicit elaboration of a three-level system. The results are amenable to analytical evaluation once the interaction potential is prescribed, and extensions of the approach to include multiphonon processes are straightforward.

Physical review. B, Condensed matter•Nov 15, 1986•12 citations

Double optical resonance

R. M. Whitley, Carlos R. Stroud

A complete and detailed treatment of a three-level atom interacting with two near-resonant monochromatic fields is presented. It is assumed that the only damping mechanism is radiative damping, and that the atoms all have the same resonance frequencies, as is the case in an atomic beam. Detailed analytic solutions as well as numerical examples are determined from quantum-electrodynamic equations of motion. In addition, approximation techniques are presented which allow one to get accurate quantitative predictions for strong applied fields from simple rate-equation-like arguments. Absorption and emission spectra are determined, as are the transient and steady-state response of the atom. Two of the more interesting predictions are an emission spectrum containing up to seven components and a prediction of steady-state populations larger than 0.5 in the second excited state.

Physical Review A•Oct 1, 1976•460 citations
Algebraic methods are developed for deriving steady-state solutions of the Bloch equations for a system of NNN atomic (molecular) levels resonantly coupled to strong coherent radiation fields in the rotating-wave approximation, and undergoing thermal (radiative and collisional) homogeneous relaxation. These methods are applied to a "ladder" model, in which the excitation and relaxation occur by one-level steps, with one field mode in resonance with each step. Explicit solution (in terms of coupling strengths, relaxation rates, and frequency detunings) is given for the three-level system, and some observations are made on systems of four or more levels. The process of solution of the N2{N}^{2}N2-dimensional set of Bloch equations involves matrices of dimension N\ensuremath−1N\ensuremath{-}1N\ensuremath−1 or less.
The resonant response of a multilevel atomic system to strong coherent radiation is analyzed using an extension of the methods of time-independent scattering theory, adapted to the density-matrix formalism in order to include thermal bath effects. General steady-state expressions are derived for self-attenuation and resonance scattering rates in strong saturating fields, as functions of the coupling strengths, relaxation parameters, and frequency detunings. Formal expressions are given for radiative-damping and collision-broadening relaxation parameters, relating the latter to scattering amplitudes. Modifications of collision-broadening parameters by the presence of very strong fields are discussed. The Bloch equations are derived by transformation to the time domain, under specified conditions.
Calculations are made to determine the response (power absorbed, magnetization, etc.) of a multilevel quantum system under the influence of any number of classically described driving fields (well defined in amplitude and phase). A nonperturbative theory is developed to account for those fields that are in resonance with the system. The nonresonant effects, such as virtual energy shifts, are included in the theory. We limit ourselves to a discussion of quantum systems that are in weak contact with a thermal reservoir. The procedure is the following A projection-operator formalism is developed which separates the density matrix of a system into two parts. One part is related to those portions of the driving fields that interact quite strongly with the system. The other part is the nonresonant or weakly interacting portion. An exact equation of motion, which includes the effects of the nonresonant part, is derived for the strongly interacting part of the density matrix. It is then shown that when relaxation can be represented by phenomenological decay constants, a unitary transformation can be found which reduces the equation of motion for the strongly interacting part of the density matrix so that an exact solution is possible. This solution is shown to give the major effects of the driving fields and can be used as the zeroth-order solution in a perturbation treatment of the whole density matrix. Frequency shifts such as the Bloch-Siegert shift and shifts due to couplings between the levels of interest (resonance levels) and other levels (nonresonance levels) all arise in the same natural way in our treatment. Our results in many instances are the extensions of the well-known results for a two-level quantum-mechanical systemm to an NNN-level one, and include resonant multiple quantum effects. As an example, a straightforward application of the method is carried out in order to compute the shifts in the resonance frequencies of a four-level system, driven by two oscillating fields connecting three of the levels, due to the counter-rotating components of the driving fields and the presence of the fourth level, which is not coupled to the other levels by the driving fields.
The coherent excitation of a three level atom by one- and two-photon resonances coupled by a common level is treated by the method of averages. The equations for the density matrix of the three resonant levels are solved analytically for square pulses of duration shorter than relaxation times. Double free induction decay occuring when both exciting fields are switched out of resonance simultaneously is exhibited. The emitted radiation is also calculated for an experiment in which the field driving the one-photon resonance remains on after the other field ends, and it is shown that experiments at several detunings and amplitudes would allow determination of various combinations of relaxation rates. Numerical studies for nonsquare pulses are briefly described. The results show that the main qualitative features of the square-pulse case are retained. 15 references.
Adsorbed atoms on the surface of a harmonic lattice are immersed in a strong laser field. The optical Bloch equations are derived, which include the thermal relaxation and the coherent excitation of the adbond. This is accomplished by a transformation to dressed states, which diagonalizes the interaction with the laser. The single-phonon couplings are then understood as transitions between dressed states. The radiative contributions for arbitrarily strong fields are obtained in the master equation, and it is shown that the coherences with respect to the dressed states decay exponentially, due to the phonon relaxation. General properties of the competing phonon-induced redistribution and optical excitation of the level populations are presented, and exemplified by an explicit elaboration of a three-level system. The results are amenable to analytical evaluation once the interaction potential is prescribed, and extensions of the approach to include multiphonon processes are straightforward.
A complete and detailed treatment of a three-level atom interacting with two near-resonant monochromatic fields is presented. It is assumed that the only damping mechanism is radiative damping, and that the atoms all have the same resonance frequencies, as is the case in an atomic beam. Detailed analytic solutions as well as numerical examples are determined from quantum-electrodynamic equations of motion. In addition, approximation techniques are presented which allow one to get accurate quantitative predictions for strong applied fields from simple rate-equation-like arguments. Absorption and emission spectra are determined, as are the transient and steady-state response of the atom. Two of the more interesting predictions are an emission spectrum containing up to seven components and a prediction of steady-state populations larger than 0.5 in the second excited state.