Temperature and magnetic field effects on the coherent and saturating resonances in Λ- and V-type systems for the 85Rb-D2 transition
TL;DR: In this paper, the effect of the external magnetic field on the EIT resonance was investigated for the 85Rb-D2 transition in both Λ-and V-type systems.
Abstract: Variations of the coherent resonance, i.e. an electromagnetically induced transparency (EIT) peak with the cell temperature in Λ- and V-type systems are observed for the 85Rb-D2 transition. In a Λ-type system, the amplitude of the EIT peak gradually decreases and it is finally masked by the broadened optical pumping dips with the increase of the cell temperature. But for the V-type system, the EIT and the saturation peaks are greatly enhanced with the increase of the cell temperature. The effect of the external magnetic field on the EIT resonance is also investigated considering both types of systems. For the Λ-type system in place of a single EIT resonance, five transparency windows with broadened width and reduced contrast are obtained depending on the Zeeman levels formed by the applied magnetic field. In the V-type system, the coherent resonance peak could not be resolved in the presence of the external magnetic field, but a greater number of saturation peaks with broadened width appear in the probe transmission spectrum. A theoretical model is adopted to represent the experimental results. Good agreement is found between the experimental and numerically simulated results.
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TL;DR: In this paper, the absorption and dispersion properties of a weak tunable probe field in a four-level Y-type atomic system driven by two strong laser (coupling) fields within the framework of density matrix formalism were studied.
Abstract: We study the absorption and dispersion properties of a weak tunable probe field in a four-level Y-type atomic system driven by two strong laser (coupling) fields within the framework of density matrix formalism. It is found that the probe absorption profile displays double-electromagnetically induced transparency (double-EIT) and it is shown how to control it by changing the Rabi frequencies as well as the atom field detuning of the coupling fields.
25 citations
TL;DR: In this article, a nanoscale plasmonic enhanced Electromagnetic Induced Transparency (EIT) and Velocity Selective Optical Pumping (VSOP) effects in miniaturized Integrated Quantum Plasmoner Device (IQPD) for D2 transitions in rubidium (Rb) were observed.
Abstract: In this work, we experimentally observe for the first time nanoscale plasmonic enhanced Electromagnetically Induced Transparency (EIT) and Velocity Selective Optical Pumping (VSOP) effects in miniaturized Integrated Quantum Plasmonic Device (IQPD) for D2 transitions in rubidium (Rb). Our device consists of a vapor cell integrated on top of a prism coated with a thin layer of metal. This configuration is known to allow efficient excitation of Surface Plasmon Resonance (SPR). The evanescent field of the surface plasmon mode interacts with the atomic media in close vicinity to the metal. In spite of the limited interaction length between SPR and Rb atoms, the signature of EIT along with VSOP signals could be clearly observed in our miniaturized IQPD under proper conditions of pump and probe intensities. A gradual decrease in the contrast of the plasmonic enhanced EIT and VSOP signals was observed as the excitation was detuned from the SPR critical angle, due to reduction in electromagnetic field enhancement,...
21 citations
TL;DR: In this paper, a detail theoretical analysis based on density matrix formulation is carried out to study the electromagnetically induced transparency in a multilevel open V-type system and the effect of decoherence on the EIT peak is studied using the theoretical model.
16 citations
TL;DR: In this paper, the splitting of hyperfine sublevels of the 85Rb atom in strong magnetic fields has been studied by means of the coherent population trapping technique, and the break of the coupling between the electronic and nuclear moments, as well as the transition to the Paschen-Back regime in magnetic fields above 600 G, has been observed.
Abstract: The splitting of hyperfine sublevels of the 85Rb atom in strong magnetic fields has been studied by means of the coherent population trapping technique. Narrow resonances with a high signal-to-noise ratio have been detected in a 30-μm-thick spectroscopic cell. The magnetic field in the direction transverse to the laser beams has been created by permanent magnets and has reached 1600 G. Owing to the exclusive narrowness of the cell, the field in it is almost uniform. The break of the coupling between the electronic and nuclear moments, as well as the transition to the Paschen-Back regime in magnetic fields above 600 G, has been observed. The derivatives of the frequency shifts of the observed resonances and their asymptotic values in strong magnetic fields have been determined in terms of the magnetic field strength. The experimental results have been interpreted within a theoretical model based on the known constants of the hyperfine structure of the Rb atom.
13 citations
TL;DR: The magnitude and sign of self-Kerr nonlinear coefficient in a degenerate two-level inhomogeneously broadened medium are simply controlled by an external magnetic field.
12 citations
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TL;DR: The mathematical theory of the method is explained in detail, followed by a thorough description of MEG instrumentation, data analysis, and practical construction of multi-SQUID devices.
Abstract: Magnetoencephalography (MEG) is a noninvasive technique for investigating neuronal activity in the living human brain. The time resolution of the method is better than 1 ms and the spatial discrimination is, under favorable circumstances, 2-3 mm for sources in the cerebral cortex. In MEG studies, the weak 10 fT-1 pT magnetic fields produced by electric currents flowing in neurons are measured with multichannel SQUID (superconducting quantum interference device) gradiometers. The sites in the cerebral cortex that are activated by a stimulus can be found from the detected magnetic-field distribution, provided that appropriate assumptions about the source render the solution of the inverse problem unique. Many interesting properties of the working human brain can be studied, including spontaneous activity and signal processing following external stimuli. For clinical purposes, determination of the locations of epileptic foci is of interest. The authors begin with a general introduction and a short discussion of the neural basis of MEG. The mathematical theory of the method is then explained in detail, followed by a thorough description of MEG instrumentation, data analysis, and practical construction of multi-SQUID devices. Finally, several MEG experiments performed in the authors' laboratory are described, covering studies of evoked responses and of spontaneous activity in both healthy and diseased brains. Many MEG studies by other groups are discussed briefly as well.
4,533 citations
TL;DR: In this paper, the authors consider the atomic dynamics and the optical response of the medium to a continuous-wave laser and show how coherently prepared media can be used to improve frequency conversion in nonlinear optical mixing experiments.
Abstract: Coherent preparation by laser light of quantum states of atoms and molecules can lead to quantum interference in the amplitudes of optical transitions. In this way the optical properties of a medium can be dramatically modified, leading to electromagnetically induced transparency and related effects, which have placed gas-phase systems at the center of recent advances in the development of media with radically new optical properties. This article reviews these advances and the new possibilities they offer for nonlinear optics and quantum information science. As a basis for the theory of electromagnetically induced transparency the authors consider the atomic dynamics and the optical response of the medium to a continuous-wave laser. They then discuss pulse propagation and the adiabatic evolution of field-coupled states and show how coherently prepared media can be used to improve frequency conversion in nonlinear optical mixing experiments. The extension of these concepts to very weak optical fields in the few-photon limit is then examined. The review concludes with a discussion of future prospects and potential new applications.
4,218 citations
TL;DR: In this paper, an experimental demonstration of electromagnetically induced transparency in an ultracold gas of sodium atoms, in which the optical pulses propagate at twenty million times slower than the speed of light in a vacuum, is presented.
Abstract: Techniques that use quantum interference effects are being actively investigated to manipulate the optical properties of quantum systems1. One such example is electromagnetically induced transparency, a quantum effect that permits the propagation of light pulses through an otherwise opaque medium2,3,4,5. Here we report an experimental demonstration of electromagnetically induced transparency in an ultracold gas of sodium atoms, in which the optical pulses propagate at twenty million times slower than the speed of light in a vacuum. The gas is cooled to nanokelvin temperatures by laser and evaporative cooling6,7,8,9,10. The quantum interference controlling the optical properties of the medium is set up by a ‘coupling’ laser beam propagating at a right angle to the pulsed ‘probe’ beam. At nanokelvin temperatures, the variation of refractive index with probe frequency can be made very steep. In conjunction with the high atomic density, this results in the exceptionally low light speeds observed. By cooling the cloud below the transition temperature for Bose–Einstein condensation11,12,13 (causing a macroscopic population of alkali atoms in the quantum ground state of the confining potential), we observe even lower pulse propagation velocities (17?m?s−1) owing to the increased atom density. We report an inferred nonlinear refractive index of 0.18?cm2?W−1 and find that the system shows exceptionally large optical nonlinearities, which are of potential fundamental and technological interest for quantum optics.
3,438 citations
TL;DR: In this paper, the authors report the first demonstration of a technique by which an optically thick medium may be rendered transparent by applying a temporally smooth coupling laser between a bound state of an atom and the upper state of the transition which is to be made transparent.
Abstract: We report the first demonstration of a technique by which an optically thick medium may be rendered transparent. The transparency results from a destructive interference of two dressed states which are created by applying a temporally smooth coupling laser between a bound state of an atom and the upper state of the transition which is to be made transparent. The transmittance of an autoionizing (ultraviolet) transition in Sr is changed from exp(-20) without a coupling laser present to exp(-1) in the presence of a coupling laser.
2,325 citations
Proceedings Article•
12 May 1991TL;DR: The first demonstration of a technique by which an optically thick medium may be rendered transparent is reported, which results from a destructive interference of two dressed states created by applying a temporally smooth coupling laser between a bound state of an atom and the upper state of the transition which is to be made transparent.
Abstract: We report the results of an experiment showing how an opaque atomic transition in neutral Strontium may be rendered transparent to radiation at its resonance frequency. This is accomplished by applying an electromagnetic coupling field (Fig. 1) between the upper state 4d5d1D2 of the transition and another state 4d5p1D2; of the atom. When the Rabi frequency of the coupling field exceeds the inhomogeneous width of the 5s5p1P1–4d5d1D2; transition, the medium becomes transparent on line center.
1,999 citations