Electromagnetically-induced transparency and slow light in room temperature 4He*
TL;DR: In this article, the authors have observed transparency in ultra-narrow (<10 kHz) windows at the resonant 1.083 μm transition for purely electronic spins in gaseous 4He* at room temperature.
Abstract: Electromagnetically-induced transparency (EIT) in three-level Λ-systems is based on quantum interference effects involving coherence between the two lower levels, which allow propagation of a resonant probe light beam in the presence of a strong coupling field. We have observed transparency in ultra-narrow (<10 kHz) windows at the resonant 1.083 μm transition for purely electronic spins in gaseous 4He* at room temperature. Slow light is an interesting outcome of the EIT phenomenon due to extreme dispersion within the narrow transparency window. We have obtained group delays of about 4 μs in a 2.5 cm long He* cell. A complete theoretical analysis explains our observations emphasizing the positive role of collisions. Slow light with 1-GHz Doppler broadening opens the door to applications of controllable large-bandwidth delays in radars.
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Proceedings Article•
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12 May 1991
TL;DR: In this article, the probe energy is increased to 150 n3 (10" W/cm ) and the absorption cross section at the transmission maximum increases by a factor of approximately 2.
Abstract: As stated in the text, Figs. 3 and 4 (transmission versus probe laser detuning) were taken at an energy of 10 nJ in a 0.5-mm-diam beam. We should have noted that when the probe energy is increased to 150 n3 (— 10" W/cm ) the absorption cross section at the transmission maximum increases by a factor of approximately 2. At this energy density, with or without the coupling laser present, transmitted probe energy is no longer linear with incident probe energy.
331 citations
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TL;DR: In this article, the EIT windows were obtained for purely electronic spins in the presence of Doppler broadening and the positive role of collisions was emphasized through measurements of the power dependence of EIT resonance.
Abstract: Electromagnetically induced transparency (EIT) is observed in gaseous 4He at room temperature. Ultra-narrow (less than 10 kHz) EIT windows are obtained for the first time for purely electronic spins in the presence of Doppler broadening. The positive role of collisions is emphasized through measurements of the power dependence of the EIT resonance. Measurement of slow light opens up possible ways to applications.
25 citations
Dissertation•
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27 Mar 2012
TL;DR: In this paper, a methode originale permettre de restaurer l'EIT en creusant localement the distribution of vitesses, conclut a l'existence de classes de vitesses atomiques particulieres, responsables de la diminution de la transparence.
Abstract: Parce qu'il permet une interaction lumiere-matiere forte, controlable, et coherente, le phenomene de transparence induite electromagnetiquement (EIT) trouve aujourd'hui des applications dans un champ tres large de la physique. Cependant, sur la raie D2 du 133Cs, la transparence experimentalement mesuree est tres faible en presence d'elargissement inhomogene. Nous menons donc une etude theorique qui prend en compte les multiples niveaux excites de la raie et precise leur influence sur l'EIT. Elle conclut a l'existence de classes de vitesses atomiques particulieres, responsables de la diminution de la transparence. Nous proposons alors une methode originale permettant de restaurer l'EIT en creusant localement la distribution de vitesses. L'augmentation ainsi prevue de la transparence est ensuite verifiee experimentalement. Deux experiences de memoire par EIT sont ensuite presentees. Dans la premiere, deux quadratures orthogonales d'une bande laterale unique sont stockees dans une vapeur chaude de cesium, puis relues sans mesurer d'exces de bruit. Dans la seconde, le stockage d'un etat coherent en regime de photon unique est obtenu dans un nuage d'atomes froids. Afin de preparer le stockage de lumiere non classique, l'asservissement de la mesure d'un etat comprime sur une quadrature fixe a ete realise. Ce montage doit permettre de demontrer l'intrication deterministe de deux ensembles atomiques.
1 citations
References
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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.
3,254 citations
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TL;DR: In this paper, small group velocities of order 90 m/s and large group delays of greater than 0.26 ms were observed in an optically dense hot rubidium gas ( $\ensuremath{\approx}360\mathrm{K}$).
Abstract: We report the observation of small group velocities of order 90 m/s and large group delays of greater than 0.26 ms, in an optically dense hot rubidium gas ( $\ensuremath{\approx}360\mathrm{K}$). Media of this kind yield strong nonlinear interactions between very weak optical fields and very sharp spectral features. The result is in agreement with previous studies on nonlinear spectroscopy of dense coherent media.
1,004 citations
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TL;DR: A new laser-cooling scheme based on velocity-selective optical pumping of atoms into a nonabsorbing coherent superposition of states is presented, allowing transverse cooling of metastable metastable He atoms to a temperature of 2 K, lower than both the usual Doppler cooling limit and the one-photon recoil energy.
Abstract: We present a new laser-cooling scheme based on velocity-selective optical pumping of atoms into a nonabsorbing coherent superposition of states. This method has allowed us to achieve transverse cooling of metastable $^{4}\mathrm{He}$ atoms to a temperature of 2 \ensuremath{\mu}K, lower than both the usual Doppler cooling limit (23 \ensuremath{\mu}K) and the one-photon recoil energy (4 \ensuremath{\mu}K). The corresponding de Broglie wavelength (1.4 \ensuremath{\mu}m) is larger than the atomic-transition optical wavelength.
612 citations
Proceedings Article•
[...]
12 May 1991
TL;DR: In this article, the probe energy is increased to 150 n3 (10" W/cm ) and the absorption cross section at the transmission maximum increases by a factor of approximately 2.
Abstract: As stated in the text, Figs. 3 and 4 (transmission versus probe laser detuning) were taken at an energy of 10 nJ in a 0.5-mm-diam beam. We should have noted that when the probe energy is increased to 150 n3 (— 10" W/cm ) the absorption cross section at the transmission maximum increases by a factor of approximately 2. At this energy density, with or without the coupling laser present, transmitted probe energy is no longer linear with incident probe energy.
331 citations
[...]
TL;DR: In this article, the authors reported the observation of electromagnetically induced transparency on the collisionally broadened resonance line of Pb vapor, with the Pb atoms remaining in the ground state.
Abstract: We report the observation of electromagnetically induced transparency on the collisionally broadened resonance line of Pb vapor. By applying a 1064-nm laser beam, the transmission at 283 nm is increased by at least a factor of exp(10), with nearly all of the Pb atoms remaining in the ground state
328 citations