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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 paper, a scalable scheme for a unitary multimode operator using an optical cavity with an atomic ensemble is proposed, where the squeeze parameters can be large since they are proportional to the number of atoms.
Abstract: We propose a scalable scheme for a unitary multimode operator using an optical cavity with an atomic ensemble. We exemplify three-mode and four-mode cases and engineer the squeeze operators that are decoupled from the atomic degrees of freedom. The squeeze parameters can be large since they are proportional to the number of atoms. Using the input-output theory we show that ideal squeezed states and perfect squeezing could be approached at the output. At the same time, we show that it is possible to obtain tripartite and quadripartite Greenberger-Horne-Zeilinger entangled states for continuous variables. The responsible mechanism for both the multimode squeezing and the genuine multipartite entanglement is based on the atomic coherence controlled parametric interactions. The scalability of the scheme is simply obtained by including more transitions in the atomic system.
16 citations
TL;DR: In the limit of weak coupling between a system and its reservoir, this article derived the time-convolutionless (TCL) non-Markovian master equation for a two-level system interacting with a zero-temperature structured environment with no rotating wave approximation (NRWA).
Abstract: In the limit of weak coupling between a system and its reservoir, we derive the time-convolutionless (TCL) non-Markovian master equation for a two-level system interacting with a zero-temperature structured environment with no rotating wave approximation (NRWA). By comparing the dynamics with RWA, we demonstrate the impact of RWA on the system dynamics, as well as the effects of non-Markovianity on the preservation of atomic coherence, squeezing, and entanglement.
16 citations
TL;DR: In this paper, a perturbation treatment for Raman generation with a combination of long, short, and delayed laser pulses is presented, where the coupling and probe lasers are applied in a counterintuitive sequence, and the fast oscillatory contributions to populations and coherence are eliminated by robust adiabatic passage.
Abstract: A perturbation treatment for Raman generation with a combination of long, short, and delayed laser pulses is presented. When the coupling and probe lasers are applied in a counterintuitive sequence, the fast oscillatory contributions to populations and coherence are eliminated by robust adiabatic passage, allowing a much simpler solution to the problem. Such counterintuitive and on-resonance operation allows effective electromagnetically induced transparency to evolve so that the probe laser photons will experience no absorption yet still fully participate in the nonlinear frequency conversion. Consequently, better conversion efficiency should be possible. {copyright} {ital 1998} {ital The American Physical Society}
16 citations
TL;DR: In this article, the authors proposed a scheme to distinguish the orbital angular momentum state of the Laguerre-Gaussian (LG) beam based on the electromagnetically induced transparency modulated by a microwave field in atomic ensembles.
Abstract: We propose a scheme to distinguish the orbital-angular-momentum state of the Laguerre-Gaussian (LG) beam based on the electromagnetically induced transparency modulated by a microwave field in atomic ensembles. We show that the transverse-phase variation of a probe beam with the LG mode can be mapped into the spatial intensity distribution due to the change of atomic coherence caused by the microwave. The proposal may provide a useful tool for studying higher-dimensional quantum information based on atomic ensembles.
16 citations
TL;DR: It is confirmed that the FWM process is significantly influenced by both ladder-type and V-type two-photon coherences, which is dependent on the open degree of the hyperfine states, the laser intensity, and the laser frequency detuning.
Abstract: We investigate the effects of atomic coherence on four-wave mixing (FWM), with respect to the transition routes between the hyperfine states in the 5S1/2–5P3/2–5D5/2 transition of 87Rb atoms. By comparing the FWM spectra with the electromagnetically induced transparency (EIT) spectra of the hyperfine states, we confirm that the FWM process is significantly influenced by both ladder-type and V-type two-photon coherences. From the observed FWM signal of each hyperfine structure, we clarify the role of two-photon coherence in the FWM process under EIT, double-resonance optical pumping (DROP), and two-photon absorption (TPA) conditions in a ladder-type atomic system, which is dependent on the open degree of the hyperfine states, the laser intensity, and the laser frequency detuning.
16 citations