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 Beijing Broadcasting Institute

Positive and Negative Dispersion in Two-level Degenerate Systems

Gong Qi-Huang

Published Jan 1, 2004• 0 citations
OpenAlex

Abstract

We investigate the dispersion and absorption in the coherently prepared two-level degenerate systems. Driven by a parallel polarized light and probed by a transverse polarized light, in the degeneracy case, only the positive dispersion is obtained at the zero pump-probe detuning, as well as electromagnetic induced transparency. When magnetic field breaks the degeneracy, we find that the dispersion is shifted from positive, via negative, to positive when varying the drive Rabi frequency, which means a transition between the superluminal and subluminel group velocity. Simultaneously, in these systems, the electromagnetic induced transparency, electromagnetic induced absorption and Mollow absorption spectrum are shown in the absorption spectra.

Related papers

Combination of electromagnetically induced transparency and a mollow absorption spectrum in a degenerate two-level atomic ensemble:Fe= 1 ↔Fg= 0

Qingqing Sun, Ying Gu, Qihuang Gong

We investigate the quantum coherence effects of a closed transition F e = 1 ↔ F g = 0 driven by transverse linearly polarized light field (with [sgrave] ± components) and probed by another transverse, linearly polarized light field. Owing to the competition of two-photon gain and single-photon absorption, the absorption spectrum is shown as a combination of electromagnetically induced transparency (EIT) and Mollow absorption spectrum (MAS). In the degenerate case, the MAS covers the EIT window at the pump-probe detuning centre. In the magnetic field, two single-photon absorption peaks inside the EIT windows appear when the drive Rabi frequency is smaller than the Zeeman splitting while, when the Rabi frequency is larger than the Zeeman splitting, we find four emission peaks due to the two-photon gain. A transition from positive to negative dispersion is obtained, which means a shift between the subluminal and superluminal group velocities.

Journal of Modern Optics•Sep 1, 2004•3 citations

Quantum coherence in a degenerate two-level atomic ensemble for a transition Fe=0↔Fg=1

Ying Gu, Qingqing Sun, Qihuang Gong

For a transition ${F}_{e}=0\ensuremath{\leftrightarrow}{F}_{g}=1$ driven by a linearly polarized light and probed by a transverse light, which has two equal circular components and is orthogonal to the linear polarization of the drive field and magnetic field, quantum coherence effects are investigated. Due to the coupling between the drive Rabi frequency and the Zeeman splitting, electromagnetically induced transparency, electromagnetically induced absorption, and the transition from positive to negative dispersion are obtained, as well as the populations coherently oscillating with a pump-probe detuning in the steady state. At the zero pump-probe detuning, the subluminal and superluminal light propagations are predicted. Finally, there exist the large population fluctuations when we vary the pump-probe detuning.

arXiv:quant-ph/0211056•Physical Review A•Jun 18, 2003•29 citations

Widening and shifting of the EIT windows in a multi-driven transitionFe= 1 Fg= 2

Ying Gu, Qingqing Sun, Qihuang Gong

For a closed transition Fe = 1 ↔ Fg = 2 driven by linearly polarized light and probed by circularly polarized light, quantum coherence effects induced by the Zeeman sublevels belonging to the different states are investigated. When the Zeeman splitting Δe of the excited level is larger than the Zeeman splitting Δg of the ground level, by increasing the drive Raby frequency, only the widening of the electromagnetically induced transparency (EIT) window with positive dispersion is found. In the opposite case, i.e. Δe ≤ Δg, in a moderate drive Rabi frequency, electromagnetically induced absorption with negative dispersion is obtained due to the shifting of the transparency points. Moreover, for the case of Δe ≤ Δg, a transition from subluminal to superluminal light propagation is predicted at the zero pump–probe detuning.

Journal of Physics B Atomic Molecular and Optical Physics•Mar 23, 2004•7 citations

Electromagnetically Induced Absorption and Transparency Spectra of Degenerate Two-Level Systems with a Strong Coupling Field in Cs Vapour

赵延霆, Jianming Zhao, Liantuan Xiao +2 more

The electromagnetically induced absorption and electromagnetically induced transparency spectra of degenerate two-level systems with a strong coupling laser were observed. The frequency detuning and intensity effect of the coupling laser were demonstrated simultaneously. A dispersion-like spectrum can be obtained when the coupling laser is situated at blue-side detuning. The absorption inversion was realized when the coupling laser intensity is small. The coherent resonance has a linewidth much narrower than the natural linewidth of the optical transitions.

Chinese Physics Letters•Jan 1, 2004•0 citations

Electromagnetically induced transparency in degenerate two-level systems

I. V. Zelensky, Vyacheslav A. Mironov

The evolution of an electromagnetic wave with slowly varying polarization, which interacts resonantly with the medium formed by degenerate two-level atoms, is studied using the wave function approach under the conditions of electromagnetically induced transparency. It is shown that the amplitude of the wave field propagates at the velocity of light in such a medium. The equation obtained for the polarization parameter has a solution in the form of a simple wave. The breaking length is determined. It is shown that the velocity of propagation of polarization waves may be much smaller than the velocity of light. The proposed approach is common for two-level systems with an arbitrary degeneracy. The case of a system with Zeeman degeneracy is analyzed in detail. The dependence of the velocity of propagation of the polarization structure on the amplitude and polarization is determined for an arbitrary level degeneracy. The evolution of the polarization structure in such a medium is discussed.

Journal of Experimental and Theoretical Physics•May 1, 2002•5 citations

Superposition of Mollow profile and electromagnetically induced transparency or absorption

Yang Li-jun

The transparency and absorption of the Λ-type three-level scheme driven by two coupling fields were investigated.Mollow profile was obtained in a two-level scheme where a strong coupling field and a probing field were applied on the same optical transition between excited state and ground state.There was another coupling field which drived excited state to another ground states hyperfine level in this paper.The Λ-type three-level scheme driven by two coupling fields was introduced,and some new quantum coherent phenomena were given.It can be seen that there is superposition of Mollow profile and electromagnetically induced transparency(EIT) or electromagnetically induced absorption(EIA).The dependence of the position of EIT or EIA on Rabi frequencies and frequency detunings of two coupling fields is investigated.The results can be explained by dressed-state formalism.

Journal of Optoelectronics·laser•Jan 1, 2011•0 citations
We investigate the dispersion and absorption in the coherently prepared two-level degenerate systems. Driven by a parallel polarized light and probed by a transverse polarized light, in the degeneracy case, only the positive dispersion is obtained at the zero pump-probe detuning, as well as electromagnetic induced transparency. When magnetic field breaks the degeneracy, we find that the dispersion is shifted from positive, via negative, to positive when varying the drive Rabi frequency, which means a transition between the superluminal and subluminel group velocity. Simultaneously, in these systems, the electromagnetic induced transparency, electromagnetic induced absorption and Mollow absorption spectrum are shown in the absorption spectra.
We investigate the quantum coherence effects of a closed transition F e = 1 ↔ F g = 0 driven by transverse linearly polarized light field (with [sgrave] ± components) and probed by another transverse, linearly polarized light field. Owing to the competition of two-photon gain and single-photon absorption, the absorption spectrum is shown as a combination of electromagnetically induced transparency (EIT) and Mollow absorption spectrum (MAS). In the degenerate case, the MAS covers the EIT window at the pump-probe detuning centre. In the magnetic field, two single-photon absorption peaks inside the EIT windows appear when the drive Rabi frequency is smaller than the Zeeman splitting while, when the Rabi frequency is larger than the Zeeman splitting, we find four emission peaks due to the two-photon gain. A transition from positive to negative dispersion is obtained, which means a shift between the subluminal and superluminal group velocities.
For a transition ${F}_{e}=0\ensuremath{\leftrightarrow}{F}_{g}=1$ driven by a linearly polarized light and probed by a transverse light, which has two equal circular components and is orthogonal to the linear polarization of the drive field and magnetic field, quantum coherence effects are investigated. Due to the coupling between the drive Rabi frequency and the Zeeman splitting, electromagnetically induced transparency, electromagnetically induced absorption, and the transition from positive to negative dispersion are obtained, as well as the populations coherently oscillating with a pump-probe detuning in the steady state. At the zero pump-probe detuning, the subluminal and superluminal light propagations are predicted. Finally, there exist the large population fluctuations when we vary the pump-probe detuning.
For a closed transition Fe = 1 ↔ Fg = 2 driven by linearly polarized light and probed by circularly polarized light, quantum coherence effects induced by the Zeeman sublevels belonging to the different states are investigated. When the Zeeman splitting Δe of the excited level is larger than the Zeeman splitting Δg of the ground level, by increasing the drive Raby frequency, only the widening of the electromagnetically induced transparency (EIT) window with positive dispersion is found. In the opposite case, i.e. Δe ≤ Δg, in a moderate drive Rabi frequency, electromagnetically induced absorption with negative dispersion is obtained due to the shifting of the transparency points. Moreover, for the case of Δe ≤ Δg, a transition from subluminal to superluminal light propagation is predicted at the zero pump–probe detuning.
The electromagnetically induced absorption and electromagnetically induced transparency spectra of degenerate two-level systems with a strong coupling laser were observed. The frequency detuning and intensity effect of the coupling laser were demonstrated simultaneously. A dispersion-like spectrum can be obtained when the coupling laser is situated at blue-side detuning. The absorption inversion was realized when the coupling laser intensity is small. The coherent resonance has a linewidth much narrower than the natural linewidth of the optical transitions.
The evolution of an electromagnetic wave with slowly varying polarization, which interacts resonantly with the medium formed by degenerate two-level atoms, is studied using the wave function approach under the conditions of electromagnetically induced transparency. It is shown that the amplitude of the wave field propagates at the velocity of light in such a medium. The equation obtained for the polarization parameter has a solution in the form of a simple wave. The breaking length is determined. It is shown that the velocity of propagation of polarization waves may be much smaller than the velocity of light. The proposed approach is common for two-level systems with an arbitrary degeneracy. The case of a system with Zeeman degeneracy is analyzed in detail. The dependence of the velocity of propagation of the polarization structure on the amplitude and polarization is determined for an arbitrary level degeneracy. The evolution of the polarization structure in such a medium is discussed.
The transparency and absorption of the Λ-type three-level scheme driven by two coupling fields were investigated.Mollow profile was obtained in a two-level scheme where a strong coupling field and a probing field were applied on the same optical transition between excited state and ground state.There was another coupling field which drived excited state to another ground states hyperfine level in this paper.The Λ-type three-level scheme driven by two coupling fields was introduced,and some new quantum coherent phenomena were given.It can be seen that there is superposition of Mollow profile and electromagnetically induced transparency(EIT) or electromagnetically induced absorption(EIA).The dependence of the position of EIT or EIA on Rabi frequencies and frequency detunings of two coupling fields is investigated.The results can be explained by dressed-state formalism.