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

Acta Physica Sinica

ATTOSECOND LIGHT PULSE GENERATION IN A STRONGLY DRIVEN TWO-LEVEL ATOM

Zhongyang Wang, GONG SHANG-QING, XU ZHI-ZHAN, 中国科学院上海光学精密机械研究所，上海 201800

Published Jan 1, 1999• 8 citations
Publisher

Abstract

In this paper we investigate the phase coherence of hyper-Raman lines in strongly driven two-level systems, and find that when the coherent superposition of excited and ground states is preparated, the high-order harmonics will disappear and the remainder of hyper-Raman lines in the emitted specturm are highly correlated. If the corresponding amplitude and phase of the hyper-Raman lines are selected, a train of subfemtosecond pulses will be generated.

DOI
10.7498/aps.48.961

Related papers

ATTOSECOND LIGHT PULSE GENERATION IN A STRONGLY DRIVEN TWO LEVEL ATOM

Hong Yang

Abstract In this paper we investigate the phase coherence of hyper Raman lines in strongly driven two level systems, and find that when the coherent superposition of excited and ground states is preparated, the high order harmonics will disappear and the remainder of hyper Raman lines in the emitted specturm are highly correlated. If the corresponding amplitude and phase of the hyper Raman lines are selected, a train of subfemtosecond pulses will be generated.

Acta Physica Sinica•Jan 1, 1999•1 citation

Role of initial coherence in the generation of harmonics and sidebands from a strongly driven two-level atom

F. I. Gauthey, Christoph H. Keitel, P. L. Knight +1 more

We investigate the coherent and incoherent contributions of the scattering spectrum of strongly driven two-level atoms as a function of the initial preparation of the atomic system. The initial ``phasing'' of the coherent superposition of the excited and ground states is shown to influence strongly the generation of both harmonics and hyper-Raman lines. In particular, we point out conditions under which harmonic generation can be inhibited at the expense of the hyper-Raman lines. Our numerical findings are supported by approximate analytical evaluation in the dressed state picture.

Physical Review A•Jul 1, 1995•122 citations

Coherent control of high-order harmonic generation in a two-level atom driven by intense two-colour laser fields

Shangqing Gong, Zhongyang Wang, Si-de Du +1 more

We present the most prominent features in two-colour coherent control of high-order harmonic generation using a strongly driven two-level atom model, which are known to generate high harmonics as well as hyper-Raman lines with a plateau and a cut-off. Furthermore, for one laser field case, we find, when the hyper-Raman lines are located at the position of the high harmonics, that the high harmonics are strongly enhanced due to the interference effect between the high harmonics and the hyper-Raman lines. Within these conditions, by combining the laser field with another much weaker laser field, we show plentiful and strong high harmonics in the light spectrum of the driven atomic system.

Journal of Modern Optics•Sep 1, 1999•7 citations

Strengthened Hyper-Raman Lines with the Coherent Superposition State

Zhou Zhao-Yan, Yuan Jian-Min

High-order harmonic generations from a one-dimensional Coulomb potential atom are calculated with the initial state prepared as a coherent superposition between its ground and first excited states. When the energy difference of the two states is small, we can choose proper laser pulse such that the first excited state can be excited only to other bound states instead of being ionized. We show that only the hyper-Raman lines are observable instead of the harmonics. The energy difference of the ground and the first excited state can be deduced from the highest peak of the hyper-Raman lines. We further show that the similar results can be obtained by using a combination of two laser pulses with different frequencies interacting with the atom initially at the ground state.

Chinese Physics Letters•Feb 19, 2007•7 citations

The role of hyper-Raman transitions in the radiation spectrum of a strongly driven two-level atom

Pietro Paolo Corso, L. Lo Cascio, Franco Persico

Numerical results are presented on the spectrum of the light scattered into the vacuum modes by a two-level atom driven by a strong ramped field of frequency smaller than the natural atomic frequency. The attention is focused on the role of the hyper-Raman part of the spectrum, which is shown to decrease dramatically with increasing ramp time. It is suggested that this may explain lack of experimental observation of the hyper-Raman lines. For zero ramp time, the numerical intensity of both high-order harmonics and hyper-Raman peaks is shown to agree satisfactorily with previous analytical predictions except in the region of overlap of the two series of peaks. This lends support for the suggestion that the plateau in the spectrum is related to quantum-mechanical interference between high-order harmonics and hyper-Raman processes. There is also good agreement between the numerical amplitude of the plateau and previous analytical predictions. A physical mechanism for the cut-off frequency which terminates the plateau, based on approximate energy conservation in hyper-Raman transitions, is presented and is shown to be in agreement with present numerical and previous analytical results.

Journal of Modern Optics•Apr 1, 1997•7 citations

Coherent control in the generation of harmonics and hyper-Raman lines from a strongly driven two-level atom

Chengpu Liu, Shangqing Gong, Ruxin Li +1 more

We investigate the full spectrum in the two-level atomic system strongly driven by a fundamental laser field with its much weaker harmonic field whose frequency is within the cutoff domain and find that the spectrum lines are more plentiful and the plateau is significantly extended due to their interference.

Physical Review A•Feb 19, 2004•22 citations
In this paper we investigate the phase coherence of hyper-Raman lines in strongly driven two-level systems, and find that when the coherent superposition of excited and ground states is preparated, the high-order harmonics will disappear and the remainder of hyper-Raman lines in the emitted specturm are highly correlated. If the corresponding amplitude and phase of the hyper-Raman lines are selected, a train of subfemtosecond pulses will be generated.
We investigate the coherent and incoherent contributions of the scattering spectrum of strongly driven two-level atoms as a function of the initial preparation of the atomic system. The initial ``phasing'' of the coherent superposition of the excited and ground states is shown to influence strongly the generation of both harmonics and hyper-Raman lines. In particular, we point out conditions under which harmonic generation can be inhibited at the expense of the hyper-Raman lines. Our numerical findings are supported by approximate analytical evaluation in the dressed state picture.
We present the most prominent features in two-colour coherent control of high-order harmonic generation using a strongly driven two-level atom model, which are known to generate high harmonics as well as hyper-Raman lines with a plateau and a cut-off. Furthermore, for one laser field case, we find, when the hyper-Raman lines are located at the position of the high harmonics, that the high harmonics are strongly enhanced due to the interference effect between the high harmonics and the hyper-Raman lines. Within these conditions, by combining the laser field with another much weaker laser field, we show plentiful and strong high harmonics in the light spectrum of the driven atomic system.
High-order harmonic generations from a one-dimensional Coulomb potential atom are calculated with the initial state prepared as a coherent superposition between its ground and first excited states. When the energy difference of the two states is small, we can choose proper laser pulse such that the first excited state can be excited only to other bound states instead of being ionized. We show that only the hyper-Raman lines are observable instead of the harmonics. The energy difference of the ground and the first excited state can be deduced from the highest peak of the hyper-Raman lines. We further show that the similar results can be obtained by using a combination of two laser pulses with different frequencies interacting with the atom initially at the ground state.
Numerical results are presented on the spectrum of the light scattered into the vacuum modes by a two-level atom driven by a strong ramped field of frequency smaller than the natural atomic frequency. The attention is focused on the role of the hyper-Raman part of the spectrum, which is shown to decrease dramatically with increasing ramp time. It is suggested that this may explain lack of experimental observation of the hyper-Raman lines. For zero ramp time, the numerical intensity of both high-order harmonics and hyper-Raman peaks is shown to agree satisfactorily with previous analytical predictions except in the region of overlap of the two series of peaks. This lends support for the suggestion that the plateau in the spectrum is related to quantum-mechanical interference between high-order harmonics and hyper-Raman processes. There is also good agreement between the numerical amplitude of the plateau and previous analytical predictions. A physical mechanism for the cut-off frequency which terminates the plateau, based on approximate energy conservation in hyper-Raman transitions, is presented and is shown to be in agreement with present numerical and previous analytical results.