Topic
Atomic coherence
About: Atomic coherence is a research topic. Over the lifetime, 877 publications have been published within this topic receiving 29395 citations.
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TL;DR: In this article, it has been shown that coherence can yield lasing without inversion (LWI) on a time scale shorter than the decoherence time, which could be useful for making lasers at shorter wavelength.
Abstract: It has been known for two decades that coherence can yield lasing without inversion (LWI), which could be useful for making lasers at shorter wavelength. However, excitation of extreme ultraviolet and x-ray atomic transitions typically requires a plasma medium with rapid collisions, which destroy atomic coherence. Here we demonstrate LWI on a time scale shorter than the decoherence time. We show that in such a regime LWI is possible in a V -scheme with a strong coherent drive on the low-frequency transition and obtain an analytical expression for the gain of the laser pulse at high frequency. We propose an experiment in which such LWI can be realized in He plasma.
31 citations
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TL;DR: In this article, the authors revisited the laser-induced line narrowing effect in Doppler broadened systems and determined its role for dense gases where recent experimental studies have found many intriguing atomic coherence effects.
Abstract: The laser-induced line narrowing effect in Doppler broadened systems was discovered thirty years ago. We have revisited this effect to determine its role for dense gases where recent experimental studies have found many intriguing atomic coherence effects. Using the density matrix approach, we study the width of electromagnetically induced transparency under different regimes of broadening.
30 citations
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TL;DR: In this paper, a two-photon resonant non-degenerate four-wave mixing (NFWM) was studied in a dressed cascade four-level system, and the authors showed that NFWM spectrum exhibits Autler-Townes splitting, accompanied by either suppression or enhancement of the NFWM signal.
Abstract: We study two-photon resonant nondegenerate four-wave mixing (NFWM) in a dressed cascade four-level system. In the presence of a strong coupling field, the two-photon resonant NFWM spectrum exhibits Autler-Townes splitting, accompanied by either suppression or enhancement of the NFWM signal. Such phenomena are demonstrated in Ba through inducing of atomic coherence between the ground state $6{s}^{2}$ and the doubly excited autoionizing Rydberg state $6pnd$. This technique provides a spectroscopic tool for measuring not only the resonant frequency and dephasing rate but also the transition dipole moment between two highly excited atomic states.
30 citations
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TL;DR: In this article, two four-wave mixing (FWM) processes can coexist in a four-level Y-type atomic system with carefully arranged coupling laser beams, which can be tuned to overlap or separate by various frequency detunings.
Abstract: Two four-wave-mixing (FWM) processes can coexist in a four-level Y-type atomic system with carefully arranged coupling laser beams. The generated two FWM signal beams fall into two simultaneously opened dual electromagnetically induced transparency (EIT) windows, which can be tuned to overlap or separate by various frequency detunings. The authors report our experimental observation of competing FWM processes, especially mutual suppression of the two FWM signals when the two EIT windows merge in frequency. Controlling FWM processes can have important applications in wavelength conversion for optical communication.
30 citations
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TL;DR: Coherent molecular optics is performed using two-photon Bragg scattering to observe the quadratic spatial dependence of the phase of an expanding molecular cloud and atoms initially prepared in two momentum states were observed to cross pair, forming molecules in a third momentum state.
Abstract: Coherent molecular optics is performed using two-photon Bragg scattering. Molecules were produced by sweeping an atomic Bose-Einstein condensate through a Feshbach resonance. The spectral width of the molecular Bragg resonance corresponded to an instantaneous temperature of 20 nK, indicating that atomic coherence was transferred directly to the molecules. An autocorrelating interference technique was used to observe the quadratic spatial dependence of the phase of an expanding molecular cloud. Finally, atoms initially prepared in two momentum states were observed to cross pair with one another, forming molecules in a third momentum state. This process is analogous to sum-frequency generation in optics.
29 citations