This file was automatically generated from entries from the ISI (Institute for Scientific Information) databases of scientific and other academic documents, using isi2bibtex version 0.4, a perl script which converts ISI or BIDS format files to BibTeX format files for inclusion in documents typeset using the LaTeX document processor. Try perldoc isi2bibtex for instructions, or read the script. This file generated on Wednesday 27th May 2003, from file '/home/evmik/dl/CIW.cgi', which has no subject line. @ARTICLE{Xiao03, author = {Xiao, M.}, title = {Novel linear and nonlinear optical properties of electromagnetically induced transparency systems}, journal = {IEEE J. Sel. Top. Quantum Electron.}, year = {2003}, volume = {9}, pages = {86-92}, abstract = {We describe some interesting linear and nonlinear optical properties of three-level electromagnetically induced transparency (EIT) systems, such as absorption reduction, sharp dispersion change, and enhanced Kerr nonlinearity. These novel optical properties are very useful in enhancing efficient nonlinear optical processes, which can find applications in optoelectronic devices. We present some experiments done in our group in the past few years with three-level atomic systems, especially more recent experiments with EIT medium inside an optical cavity. } } @ARTICLE{LeKienLH03, author = {Le Kien, F. and Liang, J. Q. and Hakuta, K.}, title = {Slow light produced by far-off-resonance Raman scattering}, journal = {IEEE J. Sel. Top. Quantum Electron.}, year = {2003}, volume = {9}, pages = {93-101}, abstract = {The authors survey the theoretical and experimental aspects of generation of slow light in a far-off-resonance Raman medium driven by a strong coupling field. When material dispersion is negligible, the propagation of two coupled sidebands can be described in terms of two. normal modes that propagate independently at different group velocities, one at the vacuum speed of light and one at a reduced velocity. They use solid hydrogen as a Raman medium to demonstrate the generation of slow light. The numerical calculations and experimental observations show that, due to high density, narrow Raman width, and small two-photon detuning, far-off-resonance Raman scattering in solid hydrogen can slow down the pulse-peak velocity of the Stokes and anti-Stokes fields to the order of c/10000. This velocity reduction affects the amplitudes of the Stokes and anti-Stokes fields via the beating between the normal modes. the double-peak structure observed in the intensity temporal profiles of the sideband fields is a signature of the splitting of the copropagating, normal modes.} } @ARTICLE{DeyA03, author = {Dey, T. N. and Agarwal, G. S.}, title = {Storage and retrieval of light pulses at moderate powers}, journal = {Phys. Rev. A}, year = {2003}, volume = {67}, pages = {033813}, abstract = {We investigate whether it is possible to store and retrieve an intense probe pulse using a medium that can be modeled as a set of atoms with the relevant energy levels in Lambda configuration. We demonstrate that it is indeed possible to store and retrieve the probe pulses that are not necessarily weak. We find that the retrieved pulse remains a replica of the original pulse, although there is overall broadening and loss of the intensity. The loss of intensity can be understood in terms of the dependence of absorption on the intensity of the probe. Our calculations include the dynamics of the control field, which becomes especially important as the intensity of the probe pulse increases. We use the adiabatic theory of Grobe [Phys. Rev. Lett. 73, 3183 (1994)] to understand our numerical results on the storage and retrieval of light pulses at moderate powers. } } @ARTICLE{BigelowLB03, author = {Bigelow, M. S. and Lepeshkin, N. N. and Boyd, R. W.}, title = {Observation of ultraslow light propagation in a ruby crystal at room temperature}, journal = {Phys. Rev. Lett.}, year = {2003}, volume = {90}, pages = {113903}, abstract = {We have observed slow light propagation with a group velocity as low as 57.5+/-0.5 m/s at room temperature in a ruby crystal. A quantum coherence effect, coherent population oscillations, produces a very narrow spectral "hole" in the homogeneously broadened absorption profile of ruby. The resulting rapid spectral variation of the refractive index leads to a large value of the group index. We observe slow light propagation both for Gaussian-shaped light pulses and for amplitude modulated optical beams in a system that is much simpler than those previously used for generating slow light. } } @ARTICLE{FicekSSAB03, author = {Ficek, Z. and Seke, J. and Soldatov, A. V. and Adam, G. and Bogolubov, N. N.}, title = {Multilevel coherence effects in a two-level atom driven by a trichromatic field}, journal = {Opt. Commun.}, year = {2003}, volume = {217}, pages = {299-309}, abstract = {We study the absorption and dispersion properties of a weak probe field monitoring a two-level atom driven by a trichromatic field. We calculate the steady-state linear susceptibility and find that the system can produce a number of multilevel coherence effects predicted for atoms composed of three and more energy levels. Although the atom has only one transition channel, the multilevel effects are possible because there are multichannel transitions between dressed states induced by the driving field. In particular, we show that the system can exhibit multiple electromagnetically induced transparency and can also produce a strong amplification at the central frequency which is not attributed to population inversion in both the atomic bare states and in the dressed atomic states. Moreover, we show that the absorption and dispersion of the probe field is sensitive to the initial relative phase of the components of the driving field. In addition, we show that the group velocity of the probe field can be controlled by changing the initial relative phases or frequencies of the driving fields and can also be varied from subluminal to superluminal. (C) 2003 Elsevier Science B.V. All rights reserved. } } @ARTICLE{JuzeliunasMF03, author = {Juzeliunas, G. and Masalas, M. and Fleischhauer, M.}, title = {Storing and releasing light in a gas of moving atoms}, journal = {Phys. Rev. A}, year = {2003}, volume = {67}, pages = {023809}, abstract = {We propose a scheme of storing and releasing pulses or cw beams of light in a moving atomic medium illuminated by two stationary and spatially separated control lasers. The method is based on electromagnetically induced transparency but in contrast to previous schemes, storage and retrieval of the probe pulse can be achieved at different locations and without switching off the control laser. } } @ARTICLE{AgarwalD03, author = {Agarwal, G. S. and Dasgupta, S.}, title = {Laser-induced breakdown of the magnetic-field-reversal symmetry in the propagation of unpolarized light}, journal = {Phys. Rev. A}, year = {2003}, volume = {67}, pages = {023814}, abstract = {We show how a medium, under the influence of a coherent control field that is resonant or close to resonance to an appropriate atomic transition, can lead to very strong asymmetries in the propagation of unpolarized light when the direction of the magnetic field is reversed. We show how electromagnetically induced transparency (EIT) can be used in atomic vapor to mimic this magnetochiral effect that occurs in natural systems. EIT can produce much larger asymmetry than the well-known magnetochiral effect as we use the dipole-allowed transitions here. Using density-matrix calculations we present results for the breakdown of the magnetic-field-reversal symmetry for two different atomic configurations. } } @ARTICLE{GreentreeRVDdSM03, author = {Greentree, A. D. and Richards, D. and Vaccaro, J. A. and Durrant, A. V. and de Echaniz, S. R. and Segal, D. M. and Marangos, J. P.}, title = {Intensity-dependent dispersion under conditions of electromagnetically induced transparency in coherently prepared multistate atoms}, journal = {Phys. Rev. A}, year = {2003}, volume = {67}, pages = {023818}, abstract = {Interest in lossless nonlinearities has focussed on the dispersive properties of Lambda systems under conditions of electromagnetically induced transparency (EIT). We generalize the Lambda system by introducing further degenerate states to realize a "chain Lambda" atom where multiple coupling of the probe field significantly enhances the intensity-dependent dispersion without compromising the EIT condition. } } @ARTICLE{ZhuL02, author = {Zhu, K. D. and Li, W. S.}, title = {Electromagnetically induced transparency mediated by phonons in strongly coupled exciton-phonon systems}, journal = {Appl. Phys. B-Lasers Opt.}, year = {2002}, volume = {75}, pages = {861-864}, abstract = {It is shown theoretically that electromagnetically induced transparency (EIT), due to strong exciton-phonon coupling can occur in strongly coupled exciton-phonon systems such as polymers and organic semiconductors and lead to ultra-slow light effects. The results indicate that the strong coupling of excitons and phonons is important, but the excitonexciton interaction plays a small role in the generation of the EIT. Numerical results for polydiacetylene-toluene sulfonate are also presented. This EIT in a solid-state medium might be utilized for efficient multiwave mixing and quantum nondemolition measurements, as well as for novel acousto- optical devices. } } @ARTICLE{HaasK03, author = {Haas, M. and Keitel, C. H.}, title = {Low group velocity of light without an extra driving laser field}, journal = {Opt. Commun.}, year = {2003}, volume = {216}, pages = {385-389}, abstract = {Coherent light pulse propagation is investigated in a medium of three-level atoms with two possibly closely spaced upper levels without the presence of any auxiliary driving laser fields. We derive an analytic expression for the group velocity in this system and demonstrate that it may be very low along with a small pulse distortion for a certain range of intensities. The group velocity is shown to depend sensitively on the upper level splitting and may thus be conveniently controlled by a magnetic field rather than an extra laser field. (C) 2003 Elsevier Science B.V. All rights reserved. } } @ARTICLE{AlzarCGSN03, author = {Alzar, C. L. G. and Cruz, L. S. and Gomez, J. G. A. and Santos, M. F. and Nussenzveig, P.}, title = {Super-Poissonian intensity fluctuations and correlations between pump and probe fields in Electromagnetically Induced Transparency}, journal = {Europhys. Lett.}, year = {2003}, volume = {61}, pages = {485-491}, abstract = {We have measured the intensity fluctuations of pump and probe beams after interaction with Rb atoms in a situation of Electromagnetically Induced Transparency. Both fields present super-Poissonian statistics and their intensities become correlated, in good qualitative agreement with theoretical predictions in which both fields are treated quantummechanically. The intensity correlations measured are a first step towards the observation of entanglement between the fields. } } @ARTICLE{AkulshinCSHO03, author = {Akulshin, A. M. and Cimmino, A. and Sidorov, A. I. and Hannaford, P. and Opat, G. I.}, title = {Light propagation in an atomic medium with steep and signreversible dispersion}, journal = {Phys. Rev. A}, year = {2003}, volume = {67}, pages = {011801}, abstract = {We show that ground-state Zeeman coherence prepared by twophoton Raman transitions in alkali atoms results in steep controllable and sign-reversible dispersion. Pulse propagation with small negative as well as positive group velocity of light (-c/5100 and c/41 000) in a Cs vapor cell is reported. Energy exchange between copropagating light components through long- lived Zeeman coherence with enhanced absorption or transmission has been observed. } } @ARTICLE{KlimovSDY03, author = {Klimov, A. B. and Sanchez-Soto, L. L. and Delgado, J. and Yustas, E. C.}, title = {Phase states for a three-level atom interacting with quantum fields}, journal = {Phys. Rev. A}, year = {2003}, volume = {67}, pages = {013803}, abstract = {We introduce phase operators associated with the algebra su(3), which is the appropriate tool to describe three-level systems. The rather unusual properties of this phase are caused by the small dimension of the system and are explored in detail. When a three-level atom interacts with a quantum field in a cavity, a polynomial deformation of this algebra emerges in a natural way. We also introduce a polar decomposition of the atom-field relative amplitudes that leads to a Hermitian relative-phase operator, whose eigenstates correctly describe the corresponding phase properties. We claim that this is the natural variable to deal with quantum interference effects in atom-field interactions. We find the probability distribution for this variable and study its time evolution in some special cases. } } @ARTICLE{RostovtsevPLJ02, author = {Rostovtsev, Y. and Protsenko, I. and Lee, H. and Javan, A.}, title = {From laser-induced line narrowing to electromagnetically induced transparency in a Doppler-broadened system}, journal = {J. Mod. Opt.}, year = {2002}, volume = {49}, pages = {2501-2516}, 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. } } @ARTICLE{RostovtsevKS02, author = {Rostovtsev, Y. and Kocharovskaya, O. and Scully, M. O.}, title = {Stop and go control of light in hot atomic gases}, journal = {J. Mod. Opt.}, year = {2002}, volume = {49}, pages = {2637-2643}, abstract = {We consider a new way to trap light pulses inside a gaseous medium by using additional electromagnetic fields. The drive field controls the transparency and the dispersion of the medium. Applied auxiliary fields provide additional control on the propagation of the probe pulse via the dragging effect resulting from the population redistribution between hyperfine levels of different velocity groups. The density matrix calculation is performed to prove that these effects are experimentally feasible. } } @ARTICLE{KuznetsovaKHS02, author = {Kuznetsova, E. and Kocharovskaya, O. and Hemmer, P. and Scully, M. O.}, title = {Atomic interference phenomena in solids with a long-lived spin coherence}, journal = {Phys. Rev. A}, year = {2002}, volume = {66}, pages = {063802}, abstract = {We generalize the theory of electromagnetically induced transparency (EIT) and slow group velocity for the case of the homogeneous and inhomogeneous line broadening in both oneand two-photon transitions which unavoidably takes place in solid materials with a long-lived spin coherence. We identify regimes of EIT where the linewidth can be essentially reduced due to inhomogeneous broadening and, moreover, can be proportional to the amplitude of the driving field rather than the intensity. We suggest also a class of solid materials, namely, rare-earth ion doped semiconductors or dielectrics with electricdipole allowed transitions, that is very promising for realization and applications of EIT. } } @ARTICLE{PatnaikLH02, author = {Patnaik, A. K. and Liang, J. Q. and Hakuta, K.}, title = {Slow light propagation in a thin optical fiber via electromagnetically induced transparency}, journal = {Phys. Rev. A}, year = {2002}, volume = {66}, pages = {063808}, abstract = {We propose a configuration that utilizes electromagnetically induced transparency (EIT) to tailor a fiber mode propagating inside a thin optical fiber and coherently control its dispersion properties to drastically reduce the group velocity of the fiber mode. The key to this proposal is that the evanescent field of the thin fiber strongly couples with the surrounding active medium, so that the EIT condition is met by the medium. We show how the properties of the fiber mode are modified due to the EIT medium, both numerically and analytically. We demonstrate that the group velocity of the modified fiber mode can be drastically reduced (approximate to44 m/sec) using the coherently prepared orthohydrogen doped in a matrix of parahydrogen crystal as the EIT medium.} } @ARTICLE{HuDLL02, author = {Hu, Z. F. and Du, C. G. and Li, D. J. and Li, S. Q.}, title = {Atomic interaction effects on electromagnetically induced transparency and slow light in ultracold Bose gas}, journal = {Chin. Phys. Lett.}, year = {2002}, volume = {19}, pages = {1805-1807}, abstract = {We investigate electromagnetically induced transparency and slow group velocity of light in ultracold Bose gas with a twophoton Raman process. The properties of electromagnetically induced transparency and light speed can be changed by controlling the atomic interaction. Atomic interaction can be used as a knob to control the optical properties of atomic media. This can be realized in experiment by using the Feshbach resonance technique. } } @ARTICLE{HongJYM02, author = {Hong, T. and Jack, M. W. and Yamashita, M. and Mukai, T.}, title = {Enhanced Kerr nonlinearity for self-action via atomic coherence in a four-level atomic system}, journal = {Opt. Commun.}, year = {2002}, volume = {214}, pages = {371-380}, abstract = {Enhancement of optical Kerr nonlinearity for self-action by electro-magnetically induced transparency in a four-level atomic system including dephasing between the ground states is studied in detail by solving the density matrix equations for the atomic levels. We discern three major contributions, from energy shifts of the ground states induced by the probe light, to the third-order susceptibility in the four-level system. In this four-level system with the frequency-degenerate probes, quantum interference amongst the three contributions can, not only enhance the third-order susceptibility more effectively than in the three-level system with the same characteristic parameters, but also make the ratio between its real and imaginary part controllable. Due to dephasing between the two ground states and constructive quantum interference, the most effective enhancement generally occurs at an offset that is determined by the atomic transition frequency difference and the coupling Rabi frequency. (C) 2002 Elsevier Science B.V. All rights reserved. } } @ARTICLE{PayneDSA02, author = {Payne, M. G. and Deng, L. and Schmitt, C. and Anderson, S.}, title = {Studies of group-velocity reduction and pulse regeneration with and without the adiabatic approximation}, journal = {Phys. Rev. A}, year = {2002}, volume = {66}, pages = {043802}, abstract = {We present a detailed semiclassical study of the propagation of a pair of optical fields in resonant media with and without the adiabatic approximation. In the case of nearand on-resonance excitation, we show detailed calculations, both analytical and numerical, of the extremely slowly propagating probe pulse and the subsequent regeneration of a pulse via a coupling laser. Further discussions of the adiabatic approximation provide much subtle understanding of the process, including the effect on the bandwidth of the regenerated optical field. We show that the adiabatic condition does not generally predict that the regenerated field will have the same bandwidth as that of the original probe pulse. Indeed, we show analytically that for a set of coupling pulses well satisfying the adiabatic conditions, the regenerated field usually has a different bandwidth from the original probe pulse. For very-far-off resonance excitations, we show that the analytical solution is nearly detuning independent, providing a simple condition is satisfied. This surprising result is vigorously tested and compared to numerical calculations with very good agreement.} } @ARTICLE{GodoneLM02, author = {Godone, A. and Levi, F. and Micalizio, S.}, title = {Slow light and superluminality in the coherent population trapping maser}, journal = {Phys. Rev. A}, year = {2002}, volume = {66}, pages = {043804}, abstract = {The propagation of a band-limited light pulse through an atomic medium under a A excitation scheme is theoretically analyzed in this paper. We consider in particular the case where the light pulse is detected through the coherent microwave emission of the atomic ensemble (coherent population trapping maser). Significant differences are predicted with respect to the more usual optical detection (electromagnetically induced transparency signal) and found in agreement with the experimental results. Higher signal delays were observed m the microwave emission than in the optical signal with an equivalent group velocity of 6 m/s as well as highly superluminal propagation under a proper modulation scheme. The experiments were performed with a thermal Rb-87 vapor in buffer gas. } } @ARTICLE{ThanopulosS02, author = {Thanopulos, I. and Shapiro, M.}, title = {Slowing down of light by laser induced barrier hopping}, journal = {J. Chem. Phys.}, year = {2002}, volume = {117}, pages = {8404-8411}, abstract = {We suggest that a very significant reduction in the group velocity of light occurs in a laser induced barrier-hopping process, known as "Laser Catalysis.'' In this process a system is made to hop over a potential barrier via a virtual transition to an excited bound state. As in electromagnetically induced transparency (EIT), the light absorption is predicted to dip to zero at a certain frequency, thereby also changing the refractive index, inducing in turn the slowing down of the group velocity of the light. In contrast to EIT, a single pulse is predicted to induce its own transparency and in contrast to self-induced transparency the process is predicted to be insensitive to the pulse area (as long as the pulse is intense enough to meet the adiabaticity criterion). Thus, the medium becomes transparent to the light, as the laser induced barrierhopping process brings about a fundamental change in the medium. (C) 2002 American Institute of Physics. } } @ARTICLE{AkulshinCO02, author = {Akulshin, A. M. and Cimmino, A. and Opat, G. I.}, title = {Negative group velocity of a light pulse in cesium vapour}, journal = {Quantum Electron.}, year = {2002}, volume = {32}, pages = {567-569}, abstract = {Electromagnetically induced absorption in cesium vapour causes an extremely strong anomalous dispersion, leading to the propagation of radiation at a low negative group velocity V-g. As a result, a resonance light pulse appears from the medium before than a nonresonance pulse. The advance time measured in the experiment corresponds to the group velocity V-g approximate to -c/3600, which is an order of magnitude lower than that reported by Wang L.J., et al. Nature, 406, 277 (2000). } } @ARTICLE{DengHP02, author = {Deng, L. and Hagley, E. W. and Payne, M. G.}, title = {Optical wave group velocity reduction in sodium without onresonance electromagnetically induced transparency}, journal = {Opt. Commun.}, year = {2002}, volume = {212}, pages = {101-105}, abstract = {A Raman scheme for optical-pulse group velocity reduction is applied to a pure lifetime broadened sodium atomic system. In addition to the significant reduction of group velocity, probe field loss and smaller pulse distortion, as expected for such a scheme, we also investigate possible dipole moment combinations for the optimum probe pulse propagation. We show that the nuclear spin of sodium atomic system and proper laser coupling scheme can conspire to dramatically reduce the influence of any nearby state in a multi-level system, making it a nearly perfect 3-level system. (C) 2002 Elsevier Science B.V. All rights reserved. } } @ARTICLE{KozumaADHP02, author = {Kozuma, M. and Akamatsu, D. and Deng, L. and Hagley, E. W. and Payne, M. G.}, title = {Steep optical-wave group-velocity reduction and "storage" of light without on-resonance electromagnetically induced transparency}, journal = {Phys. Rev. A}, year = {2002}, volume = {66}, pages = {031801}, abstract = {We report on experimental investigation of optical-pulse groupvelocity reduction and probe-pulse "regeneration" using a Raman scheme. This scheme, which does not rely on the commonly used on-one-photon-resonance electromagnetically induced transparency (EIT) process, has many advantages over the conventional method that critically relies on the transparency window created by an EIT process. We demonstrate significant reduction of the group velocity, less probe-field loss, reduced probe-pulse distortion, and high probe-pulse regeneration efficiency. } } @ARTICLE{SoljacicJFIIJ02, author = {Soljacic, M. and Johnson, S. G. and Fan, S. H. and Ibanescu, M. and Ippen, E. and Joannopoulos, J. D.}, title = {Photonic-crystal slow-light enhancement of nonlinear phase sensitivity}, journal = {J. Opt. Soc. Am. B-Opt. Phys.}, year = {2002}, volume = {19}, pages = {2052-2059}, abstract = {We demonstrate how slow group velocities of light, which are readily achievable in photonic-crystal systems, can dramatically increase the induced phase shifts caused by small changes in the index of refraction. Such increased phase sensitivity may be used to decrease the sizes of many devices, including switches, routers, all-optical logical gates, wavelength converters, and others. At the same time a low group velocity greatly decreases the power requirements needed to operate these devices. We show how these advantages can be used to design switches smaller than 20 mum x 200 mum in size by using readily available materials and at modest levels of power. With this approach, one could have similar to10(5) such devices on a surface that is 2 cm x 2 cm, making it an important step towards large-scale all-optical integration. (C) 2002 Optical Society of America. } } @ARTICLE{DengHKP02, author = {Deng, L. and Hagley, E. W. and Kozuma, M. and Payne, M. G.}, title = {Optical-wave group-velocity reduction without electromagnetically induced transparency (vol A 65, art no 051805, 2002)}, journal = {Phys. Rev. A}, year = {2002}, volume = {66}, pages = {029903}, abstract = {} } @ARTICLE{CerboneschiRA02, author = {Cerboneschi, E. and Renzoni, F. and Arimondo, E.}, title = {Quantum interference and slow light propagation in cold samples of open three-level atoms}, journal = {J. Opt. B-Quantum Semicl. Opt.}, year = {2002}, volume = {4}, pages = {S267-S272}, abstract = {We investigate theoretically the propagation of a probe laser pulse through a cold sample of three-level atoms in the presence of a strong coupling field. Our numerical analysis shows that the electromagnetically induced transparency phenomenon produces very small group velocities for the probe pulse even if the three-level atomic system is open, i.e. in the presence of decay channels to levels not excited by the laser radiation. The role of the atomic momentum on the slow light propagation is briefly discussed. } } @ARTICLE{PaspalakisK02, author = {Paspalakis, E. and Knight, P. L.}, title = {Transparency, slow light and enhanced nonlinear optics in a four-level scheme}, journal = {J. Opt. B-Quantum Semicl. Opt.}, year = {2002}, volume = {4}, pages = {S372-S375}, abstract = {We analyse the interaction of three laser fields with a fourlevel quantum system in a tripod configuration. We obtain an analytical expression for the steady state linear susceptibility of a probe laser field and show that the system can exhibit double electromagnetically induced transparency with controlled group velocity. We also show that a coherently prepared tripod scheme can be used for efficient nonlinear generation of new laser fields. } } @ARTICLE{ArkhipkinT02, author = {Arkhipkin, V. G. and Timofeev, I. V.}, title = {Electromagnetically induced transparency; writing, storing, and reading short optical pulses}, journal = {Jetp Lett.}, year = {2002}, volume = {76}, pages = {66-70}, abstract = {The spatiotemporal propagation dynamics of a weak probe pulse in an optically dense medium of three-level atoms is studied in the adiabatic approximation under conditions of electromagnetically induced transparency. The atomic coherence induced at the dipole-forbidden transitions is found to be spatially localized. This effect is used for the analysis of the reversible writing (reading) of short optical pulses. The method of pulse time reversal is suggested. (C) 2002 MAIK "Nauka/Interperiodica". } } @ARTICLE{WangZ02, author = {Wang, K. and Zhu, S.}, title = {Storage states in ultracold collective atoms}, journal = {Eur. Phys. J. D}, year = {2002}, volume = {20}, pages = {281-292}, abstract = {We present a complete theoretical description of atomic storage states in the multimode framework by including spatial coherence in atomic collective operators and atomic storage states. We show that atomic storage states are Dicke states with the maximum cooperation number. In some limits, a set of multimode atomic storage states has been established,in correspondence with multimode Fock states of the electromagnetic field. This gives better understanding of both the quantum and coherent information of optical field can be preserved and recovered in ultracold medium. In this treatment, we discuss in detail both the adiabatic and dynamic transfer of quantum information between the field and the ultracold medium.} } @ARTICLE{JavanKLS02, author = {Javan, A. and Kocharovskaya, O. and Lee, H. and Scully, M. O.}, title = {Narrowing of electromagnetically induced transparency resonance in a Doppler-broadened medium}, journal = {Phys. Rev. A}, year = {2002}, volume = {66}, pages = {013805}, abstract = {We derive an analytic expression for the linewidth of electromagnetically induced transparency (EIT) resonance in a Doppler-broadened system. It is shown here that for relatively low intensity of the driving field the EIT linewidth is proportional to the square root of intensity and is independent of the Doppler width, similar to the laser-induced line narrowing effect described by Feld and Javan. In the limit of high intensity we recover the usual power-broadening case where the EIT linewidth is proportional to the intensity and inversely proportional to the Doppler width. } } @ARTICLE{PaspalakisK02, author = {Paspalakis, E. and Knight, P. L.}, title = {Electromagnetically induced transparency and controlled group velocity in a multilevel system}, journal = {Phys. Rev. A}, year = {2002}, volume = {66}, pages = {015802}, abstract = {We analyze the interaction of N laser fields with a (N+1)-level quantum system. A general analytic expression for the steadystate linear susceptibility for a probe-laser field is obtained and we show that the system can exhibit multiple electromagnetically induced transparency, with at most N-1 transparency windows occurring in the system. The group velocity of the probe-laser pulse can also be controlled.} } @ARTICLE{DengHKAP02, author = {Deng, L. and Hagley, E. W. and Kozuma, M. and Akamatsu, D. and Payne, M. G.}, title = {Achieving very-low-loss group velocity reduction without electromagnetically induced transparency}, journal = {Appl. Phys. Lett.}, year = {2002}, volume = {81}, pages = {1168-1170}, abstract = {A Raman method is studied experimentally for potential opticalwave group velocity reduction in resonant medium. Specifically, we show that the proposed method can achieve significant group velocity reduction comparable to the conventional electromagnetically induced transparency (EIT) method that had been exclusively used to date. In addition, we show that this method has a significantly lower loss compared to the EIT method, and has rich dynamics such as probe pulse narrowing. Such features have applications in the domain of telecommunication technology. (C) 2002 American Institute of Physics. } } @ARTICLE{CerboneschiRA02, author = {Cerboneschi, E. and Renzoni, F. and Arimondo, E.}, title = {Dynamics of slow-light formation}, journal = {Opt. Commun.}, year = {2002}, volume = {208}, pages = {125-130}, abstract = {We investigate theoretically the phenomenon of slow light in a cold sample of open three-level atoms interacting with the two light fields in the A configuration. We consider a cold atomic sample geometry such that the photon reabsorption is greatly reduced, and therefore the medium properties are determined by the single atom response. The dynamics of the slow propagating light pulse is examined, and the typical length scales for the propagation derived. We demonstrate that STIRAP is the mechanism behind the slow-light phenomenon. Furthermore, in the considered geometry a significant occupation of the excited state in the early phase of the propagation does not necessarily imply a decay of the ground-state coherence, and therefore does not inhibit the slow-light formation. (C) 2002 Elsevier Science B.V. All rights reserved. } } @ARTICLE{ArtoniBCL02, author = {Artoni, M. and Bassani, F. and Carusotto, I. and La Rocca, G. C.}, title = {The regime of electromagnetically induced transparency in optically dense media: from atoms to excitons}, journal = {Braz. J. Phys.}, year = {2002}, volume = {32}, pages = {275-283}, abstract = {The phenomenon of electromagnetically induced transparency (EIT) was discovered by Adriano Gozzini and coworkers in 1976 in Pisa. Novel schemes to investigate and exploit EIT in the optical domain have attracted much interest both in atomic and solid state systems. We discuss some of our recent theoretical results, in particular: i) a well developed EIT regime based on free exciton levels in undoped bulk crystalline Cu2O; ii) light dragging effects in moving media under EIT; iii) the coherent control of Cherenkov radiation in the EIT regime. } } @ARTICLE{ZibrovLHS02, author = {Zibrov, A. S. and Lukin, M. D. and Hollberg, L. and Scully, M. O.}, title = {Efficient frequency up-conversion in resonant coherent media}, journal = {Phys. Rev. A}, year = {2002}, volume = {65}, pages = {051801}, abstract = {We demonstrate an efficient frequency up-conversion based on generation of large atomic coherence in a cascade system. Two infrared, low power laser fields tuned to the vicinity of the two-photon transition in Rb vapor were converted spontaneously into infrared and blue radiation. Extension of the technique into other spectral regions using highly excited states seems feasible. } } @ARTICLE{DengHKP02, author = {Deng, L. and Hagley, E. W. and Kozuma, M. and Payne, M. G.}, title = {Optical-wave group-velocity reduction without electromagnetically induced transparency}, journal = {Phys. Rev. A}, year = {2002}, volume = {65}, pages = {051805}, abstract = {A Raman scheme for optical-pulse group-velocity reduction in a pure lifetime broadened system is studied. We show that this nonelectromagnetically induced transparency (NEIT) scheme has many advantages over the conventional method that critically relies on the transparency window created by an EIT process. Significant reduction of the group velocity, probe field loss, and pulse distortion are reported. In addition, rich dynamics of the propagation process are studied. } } @ARTICLE{GreentreeSdDMSV02, author = {Greentree, A. D. and Smith, T. B. and de Echaniz, S. R. and Durrant, A. V. and Marangos, J. P. and Segal, D. M. and Vaccaro, J. A.}, title = {Resonant and off-resonant transients in electromagnetically induced transparency: Turn-on and turn-off dynamics}, journal = {Phys. Rev. A}, year = {2002}, volume = {65}, pages = {053802}, abstract = {This paper presents a wide-ranging theoretical and experimental study of nonadiabatic transient phenomena in a Lambda electromagnetically induced transparency system when a strong coupling field is rapidly switched on or off. The theoretical treatment uses a Laplace transform approach to solve the time- dependent density matrix equation. The experiments are carried out in a Rb-87 magneto-optical trap. The results show transient probe gain in parameter regions not previously studied, and provide insight into the transition dynamics between bare and dressed states. } } @ARTICLE{KozlovWR02, author = {Kozlov, V. V. and Wallentowitz, S. and Raghavan, S.}, title = {Ultrahigh reflection from a medium with ultraslow group velocity}, journal = {Phys. Lett. A}, year = {2002}, volume = {296}, pages = {210-213}, abstract = {We show that an incident wavepacket at the boundary to a medium with extremely slow group velocity, experiences enhanced reflection and a substantial spatial and temporal distortion of the transmitted wavepacket. In the limit of vanishing group velocity, light cannot be transferred into the medium due to its perfect reflectivity. (C) 2002 Elsevier Science B.V. All rights reserved. } } @ARTICLE{GodoneLM02, author = {Godone, A. and Levi, F. and Micalizio, S.}, title = {Propagation and density effects in the coherent-populationtrapping maser}, journal = {Phys. Rev. A}, year = {2002}, volume = {65}, pages = {033802}, abstract = {The coherent microwave emission from an optically thick atomic ensemble in a cavity under coherent population trapping is analyzed. Transient and continuous operations are theoretically examined within the frame of a closed three-level system in the Dicke regime. The effects related to the atomic density and to the propagation in the active medium are examined with particular reference to the subnatural linewidth, the low group velocity and the shifts of the maser emission profile from the unperturbed atomic transition. The case of alkali-metal atoms submitted to a L excitation scheme is addressed in view of applications in the atomic frequency standard field. Experimental observations in agreement with the theoretical predictions are reported for the case of rubidium in a buffer gas. Apparent superluminal propagation is also reported and briefly discussed. } } @ARTICLE{QiSKLMLNFL02, author = {Qi, J. and Spano, F. C. and Kirova, T. and Lazoudis, A. and Magnes, J. and Li, L. and Narducci, L. M. and Field, R. W. and Lyyra, A. M.}, title = {Measurement of transition dipole moments in lithium dimers using electromagnetically induced transparency}, journal = {Phys. Rev. Lett.}, year = {2002}, volume = {88}, pages = {173003}, abstract = {We have observed electromagnetically induced transparency in a Doppler broadened molecular cascade system using fluorescence detection. We demonstrate that the power-dependent splitting of lines in the upper-level fluorescence excitation spectrum can be used as a new spectroscopic tool for the measurement of molecular transition dipole moment functions. } } @ARTICLE{YeZRS02, author = {Ye, C. Y. and Zibrov, A. S. and Rostovtsev, Y. V. and Scully, M. O.}, title = {Unexpected Doppler-free resonance in generalized double dark states}, journal = {Phys. Rev. A}, year = {2002}, volume = {65}, pages = {043805}, abstract = {Doppler-free resonances have been observed in Rb atomic vapor coherently driven by two strong-coupling fields in an intrinsically non-Doppler-free geometry. A four-level theoretical model explains the experimental results. The explanation of the physics is based on the interplay between coherences generated in a four-level system. } } @ARTICLE{Leonhardt02, author = {Leonhardt, U.}, title = {Theory of a slow-light catastrophe}, journal = {Phys. Rev. A}, year = {2002}, volume = {65}, pages = {043818}, abstract = {In diffraction catastrophes such as the rainbow, the wave nature of light resolves ray singularities and draws delicate interference patterns. In quantum catastrophes such as the black hole, the quantum nature of light resolves wave singularities and creates characteristic quantum effects related to Hawking radiation. This paper describes the theory behind a recent proposal [U. Leonhardt, Nature (London) 415, 406 (2002)] to generate a quantum catastrophe of slow light.} } @ARTICLE{DengKHP02, author = {Deng, L. and Kozuma, M. and Hagley, E. W. and Payne, M. G.}, title = {Opening optical four-wave mixing channels with giant enhancement using ultraslow pump waves}, journal = {Phys. Rev. Lett.}, year = {2002}, volume = {88}, pages = {143902}, abstract = {We show that by strongly modifying the dispersion properties of a four-level system, nonexisting wave mixing channels can be opened and significantly enhanced. Specifically, we show that coherent optical four-wave mixing with a pump wave mediated by electromagnetically induced transparency ( thereby propagating with an extremely slow group velocity) will lead to many orders of magnitude enhancement in the amplitude of the generated wave. Contrary to common belief, a large transparency window, which causes a large propagation velocity, actually diminishes efficient mixing wave production. } } @ARTICLE{MairHPWL02, author = {Mair, A. and Hager, J. and Phillips, D. F. and Walsworth, R. L. and Lukin, M. D.}, title = {Phase coherence and control of stored photonic information}, journal = {Phys. Rev. A}, year = {2002}, volume = {65}, pages = {031802}, abstract = {We report the demonstration of phase coherence and control for the recently developed "light-storage'' technique. Specifically, we employ a dynamic form of electromagnetically induced transparency to bring the group velocity of a light pulse to zero, thereby mapping the photonic information into an ensemble spin coherence in warm Rb vapor. We then apply a pulsed magnetic field to vary the phase of the atomic spin excitations and map the altered information back into light. We detect the resultant phase shift in an optical interferometric measurement, thus confirming that the storage process preserves phase coherence. } } @ARTICLE{ZibrovMKRWS02, author = {Zibrov, A. S. and Matsko, A. B. and Kocharovskaya, O. and Rostovtsev, Y. V. and Welch, G. R. and Scully, M. O.}, title = {Transporting and time reversing light via atomic coherence}, journal = {Phys. Rev. Lett.}, year = {2002}, volume = {88}, pages = {103601}, abstract = {We study basic issues central to the storage of quantum information in a coherently prepared atomic medium such as the role of adiabaticity. We also propose and demonstrate transporting. multiplexing, and time reversing of stored light.} } @ARTICLE{FleischhauerL02, author = {Fleischhauer, M. and Lukin, M. D.}, title = {Quantum memory for photons: Dark-state polaritons}, journal = {Phys. Rev. A}, year = {2002}, volume = {65}, pages = {022314}, abstract = {An ideal and reversible transfer technique for the quantum state between light and metastable collective states of matter is presented and analyzed in detail. The method is based on the control of photon propagation in coherently driven three-level atomic media, in which the group velocity is adiabatically reduced to zero. Form-stable coupled excitations of light and matter ("dark-state polaritons") associated with the propagation C of quantum fields in electromagnetically induced transparency are identified, their basic properties discussed and their application for quantum memories for light analyzed.} } @ARTICLE{WangGX02, author = {Wang, H. and Goorskey, D. J. and Xiao, M.}, title = {Atomic coherence induced Kerr nonlinearity enhancement in Rb vapour}, journal = {J. Mod. Opt.}, year = {2002}, volume = {49}, pages = {335-347}, abstract = {The Kerr nonlinear index of refraction for rubidium atoms is measured by using an optical ring cavity with and without electromagnetically induced transparency (EIT). Significant enhancement and inhibition of the Kerr nonlinear index is observed near resonance with EIT. The nonlinear index of refraction is measured as functions of probe and coupling frequency detunings, respectively, with and without the presence of EIT. A simple theoretical calculation including Doppler broadening is presented and is found to be in good qualitative agreement with the experimentally measured results.} } @ARTICLE{MatskoNW02, author = {Matsko, A. B. and Novikova, I. and Welch, G. R.}, title = {Radiation trapping under conditions of electromagnetically induced transparency}, journal = {J. Mod. Opt.}, year = {2002}, volume = {49}, pages = {367-378}, abstract = {Reabsorption of spontaneously emitted photons, or radiation trapping, is a process that occurs when light interacts with optically thick media. It is shown, both theoretically and experimentally, that this effect in optically thick atomic vapour leads to a decrease in transmission of coherent laser radiation propagating under conditions of electromagnetically induced transparency (EIT). A simple theory is developed taking into account the radiation trapping, which is in a good agreement with the experimental observations and exact numerical simulation. This allows better understanding of the physics of EIT in general, and properties of dense coherent atomic media in particular. } } @ARTICLE{YanRZ02, author = {Yan, M. and Rickey, E. G. and Zhu, Y. F.}, title = {Observations of absorptive photon switching and suppression of two-photon absorption in cold atoms}, journal = {J. Mod. Opt.}, year = {2002}, volume = {49}, pages = {675-685}, abstract = {Atomic coherence and interference in an atomic medium exhibiting electromagnetically induced transparency may lead to enhancement or suppression of nonlinear susceptibilities. Absorptive photon switching has been observed by constructive quantum interference, which is based on the enhanced thirdorder, nonlinear absorption in a four-level system. In a different four-level system, suppression of the two-photon absorption by destructive quantum interference has been observed. Experiments were carried out on Rb-87 atoms cooled and confined in a magneto-optical trap and the experimental results agree with theoretical calculations of simple four- level model systems. } } @ARTICLE{Wilson-GordonF02, author = {Wilson-Gordon, A. D. and Friedmann, H.}, title = {Positive and negative dispersion in a three-level A system driven by a single pump}, journal = {J. Mod. Opt.}, year = {2002}, volume = {49}, pages = {125-139}, abstract = {We extend our previous study of a nearly degenerate A threelevel system that exhibits population trapping when driven by a single pump and produces an absorption or gain doublet in the probe absorption spectrum. In particular, we show, that the probe dispersion is positive or negative between the doublet lines, and can survive Doppler broadening. For certain values of the pump Rabi frequency, the sign of the dispersion can be changed by altering the ratio of the splitting between the lower levels to the Doppler width. } } @ARTICLE{GoorskeyWBX02, author = {Goorskey, D. J. and Wang, H. and Burkett, W. H. and Xiao, M.}, title = {Effects of a highly dispersive atomic medium inside an optical ring cavity}, journal = {J. Mod. Opt.}, year = {2002}, volume = {49}, pages = {305-317}, abstract = {Atomic media inside an optical cavity can significantly alter the spectral response of the cavity. Both theoretical and experimental examinations are made of the cavity transmission with a highly dispersive intracavity multilevel atomic medium. It is found, owing to the reduced absorption and steep dispersion change accompanying electromagnetically induced transparency in such a multi-level atomic medium, that the cavity linewidth can be made much narrower than the empty cavity linewidth. Cavity linewidth narrowing is measured as a function of both the coupling beam power and the atomic density. These experimental results are in good agreement with the theoretical predictions. } } @ARTICLE{WangZ02, author = {Wang, K. G. and Zhu, S. Y.}, title = {Atomic storage states}, journal = {Chin. Phys. Lett.}, year = {2002}, volume = {19}, pages = {56-59}, abstract = {We present a complete description of atomic storage states which may appear in the electromagnetically induced transparency (EIT). The result shows that the spatial coherence has been included in the atomic collective operators and the atomic storage states. In some limits, a set of multimode atomic storage states has been established in correspondence with the multimode Fock states of the electromagnetic field. This gives a better understanding of the fact that, in EIT, the optical coherent information can be preserved and recovered.} } @ARTICLE{TurukhinSSMHH02, author = {Turukhin, A. V. and Sudarshanam, V. S. and Shahriar, M. S. and Musser, J. A. and Ham, B. S. and Hemmer, P. R.}, title = {Observation of ultraslow and stored light pulses in a solid}, journal = {Phys. Rev. Lett.}, year = {2002}, volume = {8802}, pages = {023602}, abstract = {We report ultraslow group velocities of light in an optically dense crystal of Pr doped Y2SiO5. Light speeds as slow as 45 m/s were observed, corresponding to a group delay of 66 mus. Deceleration and "stopping" or trapping of the light pulse was also observed. These reductions of the group velocity are accomplished by using a sharp spectral feature in absorption and dispersion that is produced by resonance Raman excitation of a ground-state spin coherence. } } @ARTICLE{FiurasekLP02, author = {Fiurasek, J. and Leonhardt, U. and Parentani, R.}, title = {Slow-light pulses in moving media}, journal = {Phys. Rev. A}, year = {2002}, volume = {6501}, pages = {011802}, abstract = {Slow light in moving media reaches a counterintuitive regime when the flow speed of the medium approaches the group velocity of light. Pulses can penetrate a region where a counterpropagating flow exceeds the group velocity. When the counterflow slows down, pulses are reflected. } } @ARTICLE{AlzarMN02, author = {Alzar, C. L. G. and Martinez, M. A. G. and Nussenzveig, P.}, title = {Classical analog of electromagnetically induced transparency}, journal = {Am. J. Phys.}, year = {2002}, volume = {70}, pages = {37-41}, abstract = {We present a classical analog of electromagnetically induced transparency (EIT). In a system of just two coupled harmonic oscillators subject to a harmonic driving force, we reproduce the phenomenology observed in EIT. We also describe a simple experiment with two linearly coupled RLC circuits which can be incorporated into an undergraduate laboratory. (C) 2002 American Association of Physics Teachers. } } @ARTICLE{ZhangDCXPX01, author = {Zhang, J. X. and Dong, R. F. and Chang, H. and Xie, C. D. and Peng, K. C. and Xiao, M.}, title = {Experimental demonstration of electromagnetic induced transparency and dispersion effects in Cs atom vapour}, journal = {Chin. Phys. Lett.}, year = {2001}, volume = {18}, pages = {1586-1588}, abstract = {The effects of the electromagnetically induced transparency and dispersion of a A-type three-level atomic system are experimentally measured with a vapour cell of Cs atoms. The steep dispersion at low absorption is observed. Thus a small group velocity for the probe beam is inferred from the measured dispersion curve. } } @ARTICLE{ZhuL01, author = {Zhu, K. D. and Li, W. S.}, title = {Electromagnetically induced transparency due to exciton-phonon interaction in an organic quantum well}, journal = {J. Phys. B-At. Mol. Opt. Phys.}, year = {2001}, volume = {34}, pages = {L679-L686}, abstract = {Using the bosonic exciton approximation, we show that there exists electromagnetically induced transparency (EIT) in an organic quantum well which includes the interaction of charge- transfer excitons and phonons. The numerical results indicate that the strong exciton-phonon interaction plays a key role in the generation of the EIT. Without the exciton-phonon coupling, the EIT will disappear immediately. Ultraslow light effects are also discussed in this system. } } @ARTICLE{LinLRYP01, author = {Lin, F. C. and Lee, J. M. and Rhee, Y. J. and Yi, J. H. and Park, H.}, title = {Raman scattering in coherently prepared atomic system}, journal = {Chin. Phys. Lett.}, year = {2001}, volume = {18}, pages = {1473-1475}, abstract = {Atoms in the coherent superposition state prepared by a pulse pair are used as a novel optical memory material where a single interrogation pulse will produce a new pulse pair preserving the relative amplitudes and phases of the preparing pulse pair. Such a coherent superposition state can also be specially tailored along the propagation path to generate Raman scattering in a relatively short distance with very high efficiency. } } @ARTICLE{MatskoKRWZS01, author = {Matsko, A. B. and Kocharovskaya, O. and Rostovtsev, Y. and Welch, G. R. and Zibrov, A. S. and Scully, M. O.}, title = {Slow, ultraslow, stored, and frozen light}, journal = {Advan Atom Mol Opt Phys}, year = {2001}, volume = {46}, pages = {191-242}, abstract = {} } @ARTICLE{AgarwalDM01, author = {Agarwal, G. S. and Dey, T. N. and Menon, S.}, title = {Knob for changing light propagation from subluminal to superluminal}, journal = {Phys. Rev. A}, year = {2001}, volume = {6405}, pages = {053809}, abstract = {We show how the application of a coupling field connecting the two lower metastable states of a Lambda system can produce a variety of effects on the propagation of a weak electromagnetic pulse. In principle the light propagation can be changed from subluminal to superluminal. The negative group index results from regions of anomalous dispersion and gain in susceptibility. } } @ARTICLE{YanRZ01, author = {Yan, M. and Rickey, E. G. and Zhu, Y. F.}, title = {Observation of absorptive photon switching by quantum interference}, journal = {Phys. Rev. A}, year = {2001}, volume = {6404}, pages = {041801}, abstract = {We report an experimental demonstration of photon switching by quantum interference in a four-level atomic system proposed by Harris and Yamamoto [Phys. Rev. Lett. 81, 3611 (1998)]. Quantum interference inhibits single-photon absorption but enhances third-order, two-photon-type absorption in the four-level system. We have observed greatly enhanced nonlinear absorption in the four-level system realized with cold Rb-87 atoms and demonstrated fast switching of the nonlinear absorption with a pulsed pump laser. } } @ARTICLE{MatskoRKZS01, author = {Matsko, A. B. and Rostovtsev, Y. V. and Kocharovskaya, O. and Zibrov, A. S. and Scully, M. O.}, title = {Nonadiabatic approach to quantum optical information storage}, journal = {Phys. Rev. A}, year = {2001}, volume = {6404}, pages = {043809}, abstract = {We show that there is no need for adiabatic passage in the storage and retrieval of information in the optically thick vapor of Lambda-type atoms. This information can be mapped into and retrieved out of long-lived atomic coherence with nearly perfect efficiency by strong writing and reading pulses with steep rising and falling edges. We elucidate similarities and differences between the "adiabatic" and "instant" light storage techniques, and conclude that for any switching time, an almost perfect information storage is possible if the group velocity of the signal pulse is much less than the speed of light in the vacuum c and the bandwidth of the signal pulse is much less then the width of the two-photon resonance. The maximum loss of the information appears in the case of instantaneous switching of the writing and reading fields compared with adiabatic switching, and is determined by the ratio of the initial group velocity of the signal pulse in the medium and speed of light in the vacuum c, which can be very small. Quantum restrictions to the storage efficiency are also discussed. } } @ARTICLE{ShakhmuratovOCMKM01, author = {Shakhmuratov, R. N. and Odeurs, J. and Coussement, R. and Megret, P. and Kozyreff, G. and Mandel, P.}, title = {Electromagnetically induced transparency via adiabatic following of the nonabsorbing state}, journal = {Phys. Rev. Lett.}, year = {2001}, volume = {8715}, pages = {153601}, abstract = {It is shown that the adiabatic following of the dark, nonabsorbing state improves significantly the electromagnetically induced transparency performance and slows down the group velocity of the probe pulse. This concept can be used for fast selective gating of one pulse out of a pulse train. } } @ARTICLE{DengPH01, author = {Deng, L. and Payne, M. G. and Hagley, E. W.}, title = {Propagation of light pulse in an ultra-cold atomic vapor: mechanism for the loss of the probe field}, journal = {Opt. Commun.}, year = {2001}, volume = {198}, pages = {129-133}, abstract = {We examine the role of nearby hyper-fine levels in a threelevel transparency driven system in which a slow group velocity of light propagation is anticipated. In addition to accounting for the significant (> 80\%) probe field loss, our theory can accurately model the significant (near 30\%) pulse broadening found in two recent experiments. Other excitation schemes for reducing the absorption from nearby levels are discussed. (C) 2001 Elsevier Science B.V. All rights reserved. } } @ARTICLE{PayneD01, author = {Payne, M. G. and Deng, L.}, title = {Extremely slow propagation of a light pulse in an ultracold atomic vapor: A Raman scheme without electromagnetically induced transparency}, journal = {Phys. Rev. A}, year = {2001}, volume = {6403}, pages = {031802}, abstract = {We describe a Raman scheme where the group velocity of an optical pulse can be altered dramatically. With this none electromagnetically-induced-transparency scheme, we show that when on a two-photon resonance, a light pulse can propagate with extremely slow group velocity. Both pulse narrowing and broadening can occur depending upon the choice of two-photon detuning. When using a tuned far-off two-photon resonance, we show that the pulse propagates "superluminally" in the medium with pulse narrowing. } } @ARTICLE{SilvaMAC01, author = {Silva, F. and Mompart, J. and Ahufinger, V. and Corbalen, R.}, title = {Electromagnetically induced transparency with a standing-wave drive in the frequency up-conversion regime}, journal = {Phys. Rev. A}, year = {2001}, volume = {6403}, pages = {033802}, abstract = {We study electromagnetically induced transparency for a probe traveling-wave (TW) laser field in closed Doppler-broadened three-level systems driven by a standing-wave (SW) laser field of moderate intensity (its Rabi frequencies are smaller than the Doppler width of the driven transition). We show that probe windows of transparency occur for values of the probe to drive field frequency ratio R close to half-integer values. For optical transitions and typical values of Doppler broadening for atoms in a vapor cell, we show that for R > 1 a SW drive field is appreciably more efficient than a TW drive in inducing probe transparency. As examples, we consider parameters for real cascade schemes in barium atoms with R approximate to 1.5 and in beryllium atoms with R approximate to 3.5 showing that probe transmission values well above 50\% are possible for conditions in which it is almost negligible either without driving field or with only one of the TW components of the drive. We show that a strongly asymmetric drive having two TW components with unequal intensities is even more efficient than a symmetric SW drive in inducing probe transparency. The case of arbitrary probe intensity is also considered. } } @ARTICLE{LukinI01, author = {Lukin, M. D. and Imamoglu, A.}, title = {Controlling photons using electromagnetically induced transparency}, journal = {Nature}, year = {2001}, volume = {413}, pages = {273-276}, abstract = {It is well known that a dielectric medium can be used to manipulate properties of light pulses. However, optical absorption limits the extent of possible control: this is especially important for weak light pulses. Absorption in an opaque medium can be eliminated via quantum mechanical interference, an effect known as electromagnetically induced transparency. Theoretical and experimental work has demonstrated that this phenomenon can be used to slow down light pulses dramatically, or even bring them to a complete halt. Interactions between photons in such an atomic medium can be many orders of magnitude stronger than in conventional optical materials. } } @ARTICLE{KwonKMPK01, author = {Kwon, M. and Kim, K. and Moon, H. S. and Park, H. D. and Kim, J. B.}, title = {Dependence of electromagnetically induced absorption on two combinations of orthogonal polarized beams}, journal = {J. Phys. B-At. Mol. Opt. Phys.}, year = {2001}, volume = {34}, pages = {2951-2961}, abstract = {We observed quite different spectra for electromagnetically induced absorption (EIA) in two cases where the polarizations of the lasers was orthogonally linear and counter-rotating circular, respectively. By using the density matrix equation we were able to try to confirm that the difference between them may result from the spontaneous transfer process occurring between subsystems within the system. The experimental results agree qualitatively well with the simulated spectra in the Doppler-broadened system. } } @ARTICLE{WangGX01, author = {Wang, H. and Goorskey, D. and Xiao, M.}, title = {Enhanced Kerr nonlinearity via atomic coherence in a threelevel atomic system}, journal = {Phys. Rev. Lett.}, year = {2001}, volume = {8707}, pages = {073601}, abstract = {We measure the Kerr-nonlinear index of refraction of a threelevel Lambda -type atomic system inside an optical ring cavity. The Kerr nonlinearity is modified-and greatly enhanced near atomic resonant conditions for both probe and coupling beams. The Kerr nonlinear coefficient n(2) changes sign when tli coupling beam frequency detuning switches sign, which can lead to interesting applications in optical devices such as all- optical switches. } } @ARTICLE{WangLLLW01, author = {Wang, D. Z. and Li, D. J. and Liu, X. J. and Li, S. Q. and Wang, Y. Z.}, title = {Nonlinear theory of light speed reduction in a three-level Lambda system}, journal = {Chin. Phys. Lett.}, year = {2001}, volume = {18}, pages = {1067-1068}, abstract = {We present a nonlinear theory of light velocity reduction in a three-level Lambda system based on electromagnetically induced transparency. Analysis shows that the probe field propagates with a velocity that is quite strongly dependent on its intensity instead of being merely approximately dependent on the coupling intensity. Moreover, the minimum group velocity of the probe field is analytically given for a given input power.} } @ARTICLE{ScullyZ01, author = {Scully, M. O. and Zubairy, M. S.}, title = {Quantum search protocol for an atomic array}, journal = {Phys. Rev. A}, year = {2001}, volume = {6402}, pages = {022304}, abstract = {Quantum computers can, in principle, exceed the speed of ordinary computers by taking advantage of quantum coherence and entanglement. It is possible to find a "needle in a haystack" of N-1 straws in only rootN searches by utilizing coherent superposition states. In the present paper we show how modem quantum optics may provide a simple and practicable quantum search procedure, which may also yield insights into quantum search algorithms in general. } } @ARTICLE{OpatrnyW01, author = {Opatrny, T. and Welsch, D. G.}, title = {Coupled cavities for enhancing the cross-phase-modulation in electromagnetically induced transparency}, journal = {Phys. Rev. A}, year = {2001}, volume = {6402}, pages = {023805}, abstract = {We propose an optical double-cavity resonator whose response to a signal is similar to that of an electromagnetically induced transparency (EIT) medium. A combination of such a device with a four-level EIT medium can serve for achieving large cross- Kerr modulation of a probe field by a signal field. This would offer the possibility of building a quantum logic gate based on photonic qubits. We discuss the technical requirements that are necessary for realizing a probe-photon phase shift of pi caused by a single-photon signal. The main difficulty is the requirement of an ultralow reflectivity beam splitter, and we must be able to operate a sufficiently dense cool EIT medium in a cavity. } } @ARTICLE{MustecapliogluY01, author = {Mustecaplioglu, O. E. and You, L.}, title = {Slow light propagation in trapped atomic quantum gases}, journal = {Phys. Rev. A}, year = {2001}, volume = {6401}, pages = {013604}, abstract = {We study semiclassical slow light propagation in trapped twolevel atomic quantum gases. The temperature-dependent behaviors of both group velocity and transmissions are compared for low- temperature Bose, Fermi, and Boltzman gases within the local- density approximation for their spatial density profile.} } @ARTICLE{MustecapliogluY01, author = {Mustecaplioglu, O. E. and You, L.}, title = {Propagation of Raman-matched laser pulses through a BoseEinstein condensate}, journal = {Opt. Commun.}, year = {2001}, volume = {193}, pages = {301-312}, abstract = {We investigate the role of non-uniform spatial density profiles of trapped atomic Bose-Einstein condensates in the propagation of Raman-matched laser pulses under conditions for electromagnetically induced transparency (ETT). We find that the sharp edged axial density profile of an interacting condensate (due to a balance between external trap and repulsive atomic interaction) is advantageous for obtaining ultraslow averaged group velocities. Our results are in good quantitative agreement with a recent experiment report [Nature 397 (1999) 594]. (C) 2001 Published by Elsevier Science B.V.} } @ARTICLE{ManassahG01, author = {Manassah, J. T. and Gladkova, I.}, title = {Density matrix computation of light slowing and light storage in a Lambda vapor system}, journal = {Laser Phys.}, year = {2001}, volume = {11}, pages = {801-806}, abstract = {We compute the light slowing and light storage in a Lambda vapor system using the full Maxwell-Bloch equations with no slowly varying envelope approximation in space (SVEAS) in the expression of Maxwell wave-equation and incorporating both homogeneous and inhomogeneous dephasing terms in the atomic density matrix formulation describing the dynamics of the system. } } @ARTICLE{KimKMPK01, author = {Kim, K. and Kwon, M. and Moon, H. S. and Park, H. D. and Kim, J. B.}, title = {Measurements of normal and anomalous dispersions in coherently driven Cs vapors}, journal = {J. Korean Phys. Soc.}, year = {2001}, volume = {38}, pages = {666-669}, abstract = {Negative and positive dispersions in transitions of the C-S D-2 line have been measured by setting up a homodyne Mach-Zehnder interferometer through a coherently driven atomic system. Anomalous dispersion due to the electromagnetically induced absorption (EIA) process and normal dispersion due to the electromagnetically induced transparency (EIT) process were dn/d v similar or equal to -1.8 x 10-(14) Hz(-1) and 8.7 x 10- (14) Hz(-1), which corresponded to a negative group velocity v(g) similar or equal to -c/14 and a positive one v(g) similar or equal to c/31, respectively. } } @ARTICLE{DogariuKW01, author = {Dogariu, A. and Kuzmich, A. and Wang, L. J.}, title = {Transparent anomalous dispersion and superluminal light-pulse propagation at a negative group velocity}, journal = {Phys. Rev. A}, year = {2001}, volume = {6305}, pages = {053806}, abstract = {Anomalous dispersion cannot occur in a transparent passive medium where electromagnetic radiation is being absorbed at all frequencies, as pointed out by Landau and Lifshitz. Here we show, both theoretically and experimentally, that transparent linear anomalous dispersion can occur when a gain doublet is present. Therefore, a superluminal light-pulse propagation can be observed even at a negative group velocity through a transparent medium with almost no pulse distortion. Consequently, a negative transit time is experimentally observed resulting in the peak of the incident light pulse to exit the medium even before entering it. This counterintuitive effect is a direct result of the rephasing process owing to the wave nature of light and is not at odds with either causality or Einstein's theory of special relativity. } } @ARTICLE{YanRZ01, author = {Yan, M. and Rickey, E. G. and Zhu, Y. F.}, title = {Nonlinear absorption by quantum interference in cold atoms}, journal = {Opt. Lett.}, year = {2001}, volume = {26}, pages = {548-550}, abstract = {We report an experimental observation of third-order nonlinear absorption by quantum interference in Rb-87 atoms cooled and confined in a magneto-optic trap. A coupling laser creates electromagnetically induced transparency (EIT) in a multilevel Rb system in which the third-order nonlinear absorption is enhanced by constructive quantum interference while the linear absorption is inhibited by destructive interference. Our experiment demonstrates the EIT system proposed by Harris and Yamamoto [Phys. Rev. Lett. 81, 3611 (1998)], which absorbs two photons but not one photon in the dressed-state picture. (C) 2001 Optical Society of America. } } @ARTICLE{Nakajima01, author = {Nakajima, T.}, title = {Linear and nonlinear optical properties of an autoionizing medium}, journal = {Phys. Rev. A}, year = {2001}, volume = {6304}, pages = {043804}, abstract = {We study the linear and nonlinear optical properties of autoionizing systems under the action of a single-laser field. It is found that the group velocity is greatly reduced by the presence of a neighboring autoionizing state. Conditions for self-focusing or defocusing are also derived for the case of an isolated autoionizing system. } } @ARTICLE{Bortman-ArbivWF01, author = {Bortman-Arbiv, D. and Wilson-Gordon, A. D. and Friedmann, H.}, title = {Phase control of group velocity: From subluminal to superluminal light propagation}, journal = {Phys. Rev. A}, year = {2001}, volume = {6304}, pages = {043818}, abstract = {We show that the group velocity of a weak pulse tan be manipulated by controlling the phases of two weak optical fields applied to a V-shaped three-level system. Such control can even cause the probe propagation to change from subluminal to superluminal. We consider two schemes: in the first, the excited states are coupled by decay-induced coherence, which is an inherent property of the medium, and in the second, quantum coherence is created by coupling the excited states to each other by a strong microwave field. We also discuss the group velocity reduction experienced by a single weak propagating probe due to decay-induced coherence. } } @ARTICLE{ParkB01, author = {Park, Q. H. and Boyd, R. W.}, title = {Modification of self-induced transparency by a coherent control field}, journal = {Phys. Rev. Lett.}, year = {2001}, volume = {86}, pages = {2774-2777}, abstract = {We consider self-induced transparency (SIT) in a two-level atomic system in the presence of an additional control laser field. We find that the dynamics of the SIT process an profoundly modified by the control field, in a manner reminiscent of the modification of other nonlinear optical interactions through the process of electromagnetically induced transparency. The presence of the control field allows SIT to occur under a much broader range of conditions and leads to dramatically reduced values of the group velocity of the SIT soliton. } } @ARTICLE{MatskoRFS01, author = {Matsko, A. B. and Rostovtsev, Y. V. and Fleischhauer, M. and Scully, M. O.}, title = {Anomalous stimulated Brillouin scattering via ultraslow light}, journal = {Phys. Rev. Lett.}, year = {2001}, volume = {86}, pages = {2006-2009}, abstract = {We study stimulated Brillouin scattering (SBS) in an ultradispersive coherent medium, and show that the properties of SBS change drastically when the group velocity of light in the material approaches or becomes less than the speed of sound. In particular, forward SBS not allowed in a dispersionless bulk medium takes place in the coherent medium.} } @ARTICLE{RenzoniZVA01, author = {Renzoni, F. and Zimmermann, C. and Verkerk, P. and Arimondo, E.}, title = {Enhanced absorption Hanle effect on the F-g = F -> F-e = F+1 closed transitions}, journal = {J. Opt. B-Quantum Semicl. Opt.}, year = {2001}, volume = {3}, pages = {S7-S14}, abstract = {We analyse the Hanle effect on a closed F-g --> F-e = F-g + 1 transition. Two configurations are examined, for linearly and circularly polarized laser radiation, with the applied magnetic field collinear to the laser light wavevector. We describe the peculiarities of the Hanle signal for linearly polarized laser excitation, characterized by narrow bright resonances at low laser intensities. The mechanism behind this effect is identified, and numerical solutions for the optical Bloch equations are presented for different transitions. } } @ARTICLE{KienH01, author = {Kien, F. L. and Hakuta, K.}, title = {Normal modes and propagation dynamics in a strongly driven Raman medium}, journal = {Phys. Rev. A}, year = {2001}, volume = {6302}, pages = {023807}, abstract = {We study the collinear propagation of two weak sideband fields in a far-off-resonance Raman medium driven by a strong field. We show the existence of two sideband-field superpositions called normal modes that propagate independently at different group velocities, one at the vacuum speed of light and one at a reduced velocity and with an induced relative phase shift. We find that the effect of slow group velocity on nonlinear conversion occurs via the relative group delay as well as the relative phase shift. } } @ARTICLE{PhillipsFMW01, author = {Phillips, D. F. and Fleischhauer, A. and Mair, A. and Walsworth, R. L.}, title = {Storage of light in atomic vapor}, journal = {Phys. Rev. Lett.}, year = {2001}, volume = {86}, pages = {783-786}, abstract = {We report an experiment in which a light pulse is effectively decelerated and trapped in a vapor of Rb atoms, stored for a controlled period of time, and then released on demand. We accomplish this "storage of light" by dynamically reducing the group velocity of the light pulse to zero, so that the coherent excitation of the light is reversibly mapped into a Zeeman (spin) coherence of the Rb vapor. } } @ARTICLE{KocharovskayaRS01, author = {Kocharovskaya, O. and Rostovtsev, Y. and Scully, M. O.}, title = {Stopping light via hot atoms}, journal = {Phys. Rev. Lett.}, year = {2001}, volume = {86}, pages = {628-631}, abstract = {We prove that it is possible to freeze a light pulse (i.e., to bring it to a full stop) or even to make its group velocity negative in a coherently driven Doppler broadened atomic medium via electromagnetically induced transparency (EIT). This remarkable phenomenon of the ultraslow EIT polariton is based on the spatial dispersion of the refraction index n(w,k), i.e., its wave number dependence, which is due to atomic motion and provides a negative contribution to the group velocity. This is related to, but qualitatively different from, the recently observed light slowing caused by large temporal (frequency) dispersion. } } @ARTICLE{HussPLKW01, author = {Huss, A. F. and Peer, N. and Lammegger, R. and Korsunsky, E. A. and Windholz, L.}, title = {Efficient Raman sideband generation in a coherent atomic medium}, journal = {Phys. Rev. A}, year = {2001}, volume = {6301}, pages = {013802}, abstract = {We demonstrate the efficient generation of Raman sidebands in a medium coherently prepared in a dark state by continuous-wave low-intensity laser radiation. Our experiment is performed in sodium vapor excited in Lambda configuration on the D-1 line by two laser fields of resonant frequencies omega (1) and omega (2), and probed by a third field omega (3). First-order sidebands for frequencies omega (1), omega (2) and up to the third-order sidebands for frequency omega (3) are observed. The generation starts at a power as low as 10 muW for each input field. Dependences of the intensities of both input and generated waves on the frequency difference (omega (1) - omega (2)), on the frequency omega (3), and on the optical density an investigated. } } @ARTICLE{LiuDBH01, author = {Liu, C. and Dutton, Z. and Behroozi, C. H. and Hau, L. V.}, title = {Observation of coherent optical information storage in an atomic medium using halted light pulses}, journal = {Nature}, year = {2001}, volume = {409}, pages = {490-493}, abstract = {Electromagnetically induced transparency(1-3) is a quantum interference effect that permits the propagation of light through an otherwise opaque atomic medium; a 'coupling' laser is used to create the interference necessary to allow the transmission of resonant pulses from a 'probe' laser. This technique has been used(4-6) to slow and spatially compress light pulses by seven orders of magnitude, resulting in their complete localization and containment within an atomic cloud(4). Here we use electromagnetically induced transparency to bring laser pulses to a complete stop in a magnetically trapped, cold cloud of sodium atoms. Within the spatially localized pulse region, the atoms are in a superposition state determined by the amplitudes and phases of the coupling and probe laser fields. Upon sudden turn-off of the coupling laser, the compressed probe pulse is effectively stopped; coherent information initially contained in the laser fields is 'frozen' in the atomic medium for up to 1 ms. The coupling laser is turned back on at a later time and the probe pulse is regenerated: the stored coherence is read out and transferred back into the radiation field. We present a theoretical model that reveals that the system is self-adjusting to minimize dissipative loss during the 'read' and 'write' operations. We anticipate applications of this phenomenon for quantum information processing. } } @ARTICLE{MullerHRWD00, author = {Muller, M. and Homann, F. and Rinkleff, R. H. and Wicht, A. and Danzmann, K.}, title = {Parametric dispersion in electromagnetically induced transparency}, journal = {Phys. Rev. A}, year = {2000}, volume = {6206}, pages = {060501}, abstract = {We analyze both experimentally and theoretically the phase shift of a fixed coupling laser field in a Lambda -type system induced by a tunable probe laser field. The measurements are performed with a heterodyne interferometer on a beam of cesium atoms in the D-2 line. This system exhibits electromagnetically induced transparency with a rapidly varying refractive index. The parametric dispersion of the coupling field over a range of six decades of coupling laser intensities is investigated and found to be in accord with the predictions from the semiclassical model. } } @ARTICLE{WangGBX00, author = {Wang, H. and Goorskey, D. J. and Burkett, W. H. and Xiao, M.}, title = {Cavity-linewidth narrowing by means of electromagnetically induced transparency}, journal = {Opt. Lett.}, year = {2000}, volume = {25}, pages = {1732-1734}, abstract = {Cavity-linewidth narrowing in a ring cavity that is due to the high dispersion and reduced absorption produced by electromagnetically induced transparency (EIT) in rubidium-atom vapor has been experimentally observed. The cavity linewidth with rubidium atoms under EIT conditions can be significantly narrowed. Cavity-linewidth narrowing was measured as a function of coupling beam power. (C) 2000 Optical Society of America.} } @ARTICLE{Harris00, author = {Harris, S. E.}, title = {Pondermotive forces with slow light}, journal = {Phys. Rev. Lett.}, year = {2000}, volume = {85}, pages = {4032-4035}, abstract = {This work describes atomic processes which result from the greatly enhanced longitudinal gradient force which is inherent to the propagation of slow light. These processes are (1) ballistic atom motion and atom surfing, and (2) a type of local pondermotive nonlinearity or scattering which results from free-particle sinusoidal motion and the density variation caused by this motion. } } @ARTICLE{McGloinDF00, author = {McGloin, D. and Dunn, M. H. and Fulton, D. J.}, title = {Polarization effects in electromagnetically induced transparency}, journal = {Phys. Rev. A}, year = {2000}, volume = {6205}, pages = {053802}, abstract = {We demonstrate the magnitude dependence of electromagnetically induced transparency, in a three-level cascade scheme in rubidium, on the probe and coupling field polarizations. We show that this dependence is due to the presence of the degenerate magnetic sublevels and the strengths of their relative dipole matrix elements. It is shown that this can lead to modified absorption profiles when electromagnetically induced transparency is used for spectroscopic purposes. We present theory that is in good agreement with our experiments.} } @ARTICLE{ManassahG00, author = {Manassah, J. T. and Gladkova, I.}, title = {Modifications due to local field corrections of the electromagnetically induced transparency propagation parameters in a driven optically dense three-level cascade system}, journal = {Opt. Commun.}, year = {2000}, volume = {185}, pages = {125-132}, abstract = {We compute, under conditions of electromagnetically induced transparency, the frequency dependence of the transmission coefficient and the group velocity of a probe pulse resonant with the lower transition of a three-level cascade system in the presence of a cw pump field resonant with the system's upper transition. We show that the presence of local field corrections can substantially modify the profile of both these transmission-related quantities. (C) 2000 Published by Elsevier Science B.V. } } @ARTICLE{CarusottoAL00, author = {Carusotto, I. and Artoni, M. and La Rocca, G. C.}, title = {Atomic recoil effects in slow light propagation}, journal = {Jetp Lett.}, year = {2000}, volume = {72}, pages = {289-293}, abstract = {We theoretically investigate the effect of atomic recoil on the propagation of ultraslow light pulses through a coherently driven Bose-Einstein condensed gas. For a sample at rest, the group velocity of the light pulse is the sum of the group velocity that one would observe in the absence of mechanical effects (infinite mass limit) and the velocity of the recoiling atoms (light-dragging effect). We predict that atomic recoil may give rise to a lower bound for the observable group velocities, as well as to pulse propagation at negative group velocities without appreciable absorption. (C) 2000 MAIK "Nauka / Interperiodica". } } @ARTICLE{KienH00, author = {Kien, F. L. and Hakuta, K.}, title = {Stimulated Raman scattering with slow light}, journal = {Can. J. Phys.}, year = {2000}, volume = {78}, pages = {543-559}, abstract = {We study the propagation dynamics of weak Raman sideband fields in a far-off-resonance Raman medium driven by a strong coupling field. We show that the interaction of the system with the strong field, under the conditions of high density, narrow Raman-transition width, and small two-photon detuning, results in a slow group velocity and a substantial enhancement of the injected anti-Stokes sideband field as well as an efficient generation of a Stokes sideband field. We find that the effective group velocity is the same for the two weak fields and is proportional to the field frequency difference instead of the frequency of the corresponding field. We also discuss the condition for exponential growth of the two sideband fields in the medium. We perform numerical calculations for solid hydrogen, a realistic system where the requirements for high density and small Raman width can be met. We demonstrate that the group velocity can be slowed down by several orders, and that the slow light plays a key role for the stimulated Raman scattering process in solid hydrogen. } } @ARTICLE{SautenkovLBNMFVWS00, author = {Sautenkov, V. A. and Lukin, M. D. and Bednar, C. J. and Novikova, I. and Mikhailov, E. and Fleischhauer, M. and Velichansky, V. L. and Welch, G. R. and Scully, M. O.}, title = {Enhancement of magneto-optic effects via large atomic coherence in optically dense media}, journal = {Phys. Rev. A}, year = {2000}, volume = {6202}, pages = {023810}, abstract = {We utilize the generation of large atomic coherence in optically dense media to enhance the resonant nonlinear magneto-optic effect by several orders of magnitude, thereby eliminating power broadening and improving the fundamental signal-to-noise ratio. A proof-of-principle experiment is carried out in a dense vapor of Rb atoms. Applications such as optical magnetometry, the search for Violations of parity and time-reversal symmetry, and nonlinear optics at low light levels are feasible. } } @ARTICLE{MorigiA00, author = {Morigi, G. and Agarwal, G. S.}, title = {Temperature variation of ultraslow light in a cold gas}, journal = {Phys. Rev. A}, year = {2000}, volume = {6201}, pages = {013801}, abstract = {A model is developed to explain the temperature dependence of the group velocity as observed in the experiments of Hau et al. [Nature (London) 397, 594 (1999)]. The group velocity is quite sensitive to the change in the spatial density. The inhomogeneity in the density and its temperature dependence are primarily responsible for the observed behavior. } } @ARTICLE{Khurgin00, author = {Khurgin, J. B.}, title = {Light slowing down in Moire fiber gratings and its implications for nonlinear optics}, journal = {Phys. Rev. A}, year = {2000}, volume = {6201}, pages = {013821}, abstract = {A theory of the dispersion in the Moire gratings is developed and it is shown that the group velocity of light in them can be reduced by up to three orders of magnitude. A conceptual similarity between Moire grating and the electro-magneticinduced transparency medium is demonstrated, and it is argued that for some applications the Moire gratings present a simple viable alternative to electromagnetically induced transparency.} } @ARTICLE{WangKD00, author = {Wang, L. J. and Kuzmich, A. and Dogariu, A.}, title = {Gain-assisted superluminal light propagation}, journal = {Nature}, year = {2000}, volume = {406}, pages = {277-279}, abstract = {Einstein's theory of special relativity and the principle of causality(1-4) imply that the speed of any moving object cannot exceed that of light in a vacuum (c). Nevertheless, there exist various proposals(5-18) for observing faster-than-c propagation of light pulses, using anomalous dispersion near an absorption line(4,6-8), nonlinear(9) and linear gain lines(10-18), or tunnelling barriers(19). However, in all previous experimental demonstrations, the light pulses experienced either very large absorption(7) or severe reshaping(9,19), resulting in controversies over the interpretation. Here we use gainassisted linear anomalous dispersion to demonstrate superluminal light propagation in atomic caesium gas. The group velocity of a laser pulse in this region exceeds c and can even become negative(16,17), while the shape of the pulse is preserved. We measure a group-velocity index of n(g) = -310(+/- 5); in practice, this means that a light pulse propagating through the atomic vapour cell appears at the exit side so much earlier than if it had propagated the same distance in a vacuum that the peak of the pulse appears to leave the cell before entering it. The observed superluminal light pulse propagation is not at odds with causality, being a direct consequence of classical interference between its different frequency components in an anomalous dispersion region. } } @ARTICLE{MatskoRCS00, author = {Matsko, A. B. and Rostovtsev, Y. V. and Cummins, H. Z. and Scully, M. O.}, title = {Using slow light to enhance acousto-optical effects: Application to squeezed light}, journal = {Phys. Rev. Lett.}, year = {2000}, volume = {84}, pages = {5752-5755}, abstract = {We propose a technique for achieving phase matching in Brillouin scattering in a dielectric fiber doped by three-level Lambda-type ions. This can lead to a dramatic increase of efficiency of ponderomotive nonlinear interaction between the electromagnetic waves and holds promise for applications in quantum optics such as squeezing and quantum nondemolition measurements. } } @ARTICLE{Imamoglu00, author = {Imamoglu, A.}, title = {Electromagnetically induced transparency with two dimensional electron spins}, journal = {Opt. Commun.}, year = {2000}, volume = {179}, pages = {179-182}, abstract = {The electronic spin degrees of freedom in semiconductors have coherence times that are several orders of magnitude longer than other relevant timescales. We show that application of a pair of laser fields, whose frequencies differ by the Zeeman splitting, gives rise to electromagnetically induced transparency in an optically dense two-dimensional electron gas under high magnetic fields. Even though reduction in group velocity and enhancement of photon-photon interaction is largest for filling factor nu = 1, the effect should be observable for any 1 less than or equal to nu < 2. (C) 2000 Elsevier Science B.V. All rights reserved. } } @ARTICLE{FleischhauerYL00, author = {Fleischhauer, M. and Yelin, S. F. and Lukin, M. D.}, title = {How to trap photons? Storing single-photon quantum states in collective atomic excitations}, journal = {Opt. Commun.}, year = {2000}, volume = {179}, pages = {395-410}, abstract = {We show that it is possible to 'store' quantum states of single-photon fields by mapping them onto collective meta- stable states of an optically dense, coherently driven medium inside an optical resonator. An adiabatic technique is suggested which allows to transfer non-classical. correlations from traveling-wave single-photon wave-packets into atomic states and vise versa with nearly 100\% efficiency. In contrast to previous approaches involving single atoms, the present technique does not require the strong coupling regime corresponding to high-Q micro-cavities. Instead, intracavity electromagnetically Induced Transparency is used to achieve a strong coupling between the cavity mode and the atoms. (C) 2000 Elsevier Science B.V. All rights reserved. } } @ARTICLE{FleischhauerL00, author = {Fleischhauer, M. and Lukin, M. D.}, title = {Dark-state polaritons in electromagnetically induced transparency}, journal = {Phys. Rev. Lett.}, year = {2000}, volume = {84}, pages = {5094-5097}, abstract = {We identify form-stable coupled excitations of light and matter ("dark-state polaritons") associated with the propagation of quantum fields in electromagnetically induced transparency. The properties of dark-state polaritons such as the group velocity are determined by the mixing angle between light and matter components and can be controlled by an external coherent field as the pulse propagates. In particular, light pulses can be decelerated and "trapped" in which case their shape and quantum state are mapped onto metastable collective states of matter. Possible applications of this reversible coherent-control technique are discussed. } } @ARTICLE{RenzoniA00, author = {Renzoni, F. and Arimondo, E.}, title = {Steep dispersion in coherent population trapping with losses}, journal = {Opt. Commun.}, year = {2000}, volume = {178}, pages = {345-353}, abstract = {The dispersive properties of coherent population trapping with losses are investigated. We consider a cold sample of open three-level atoms interacting with two laser fields in the Lambda configuration. We show that despite the population losses the slope of the dispersion at Raman resonance reaches at large interaction time a constant nonzero value. A numerical study of the propagation of a pulse in the medium in the presence of a strong coupling field shows that very small group velocities for the pulse are obtained also in the presence of population losses. (C) 2000 Elsevier Science B.V. All rights reserved. } } @ARTICLE{FleischhauerLMS00, author = {Fleischhauer, M. and Lukin, M. D. and Matsko, A. B. and Scully, M. O.}, title = {Threshold and linewidth of a mirrorless parametric oscillator}, journal = {Phys. Rev. Lett.}, year = {2000}, volume = {84}, pages = {3558-3561}, abstract = {We analyze the above-threshold behavior of a mirrorless parametric oscillator based on resonantly enhanced four-wave mixing in a dense atomic vapor. It is shown that, in the ideal limit, an arbitrary small flux of pump photons is sufficient to reach the oscillator threshold. We demonstrate that, due to the large group velocity delays associated with electromagnetically induced transparency, an extremely narrow oscillator linewidth is possible, making a narrow-band source of nonclassical radiation feasible. } } @ARTICLE{LeonhardtP00, author = {Leonhardt, U. and Piwnicki, P.}, title = {Relativistic effects of light in moving media with extremely low group velocity}, journal = {Phys. Rev. Lett.}, year = {2000}, volume = {84}, pages = {822-825}, abstract = {A moving dielectric medium acts as an effective gravitational field on light. One can use media with extremely low group velocities [Lene Vestergaard Hau ct al., Nature (London) 397, 593(1999)] to create dielectric analogs of astronomical effects on Earth. In particular, a vortex flow imprints a long-ranging topological effect on incident light and can behave like an optical black hole. } } @ARTICLE{AkulshinBL99, author = {Akulshin, A. M. and Barreiro, S. and Lezama, A.}, title = {Steep anomalous dispersion in coherently prepared Rb vapor}, journal = {Phys. Rev. Lett.}, year = {1999}, volume = {83}, pages = {4277-4280}, abstract = {Steep dispersion of opposite signs in driven degenerate twolevel atomic transitions have been predicted and observed on the D-2 line of Rb-87 in an optically thin vapor cell. The intensity dependence of the anomalous dispersion has been studied. The maximum observed value of anomalous dispersion (dn/d nu similar or equal to -6 x 10(-11) Hz(-1)) corresponds to a negative group velocity V-g similar or equal to -c/23 000.} } @ARTICLE{BudkerKRY99, author = {Budker, D. and Kimball, D. F. and Rochester, S. M. and Yashchuk, V. V.}, title = {Nonlinear magneto-optics and reduced group velocity of light in atomic vapor with slow ground state relaxation}, journal = {Phys. Rev. Lett.}, year = {1999}, volume = {83}, pages = {1767-1770}, abstract = {The dynamics of resonant light propagation in rubidium vapor in a cell with antirelaxation wall coating are investigated. We change the polarization of the input light and measure the time dependence of the polarization after the cell. The observed dynamics are shown to be analogous to those in electromagnetically induced transparency. Spectral dependence of light pulse delays is found to be similar to that of nonlinear magneto-optic rotation. Delays up to approximate to 13 ms are observed, corresponding to a 8 m/s group velocity. Fields of a few microgauss are used to control the group velocity. } } @ARTICLE{KashSZHWLRFS99, author = {Kash, M. M. and Sautenkov, V. A. and Zibrov, A. S. and Hollberg, L. and Welch, G. R. and Lukin, M. D. and Rostovtsev, Y. and Fry, E. S. and Scully, M. O.}, title = {Ultraslow group velocity and enhanced nonlinear optical effects in a coherently driven hot atomic gas}, journal = {Phys. Rev. Lett.}, year = {1999}, volume = {82}, pages = {5229-5232}, 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 (approximate to 360 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. } } @ARTICLE{HarrisS98, author = {Harris, S. E. and Sokolov, A. V.}, title = {Subfemtosecond pulse generation by molecular modulation}, journal = {Phys. Rev. Lett.}, year = {1998}, volume = {81}, pages = {2894-2897}, abstract = {We suggest a technique for producing subfemtosecond pulses of radiation. The technique is based on using electromagnetically induced transparency to produce a strongly driven molecular coherence. This coherence results in a Raman spectrum with Bessel function amplitudes and phases corresponding to a frequency modulated signal, thereby allowing compression by the group velocity dispersion of the same medium. } } @ARTICLE{SchmidtWHM96, author = {Schmidt, O. and Wynands, R. and Hussein, Z. and Meschede, D.}, title = {Steep dispersion and group velocity below c/3000 in coherent population trapping}, journal = {Phys. Rev. A}, year = {1996}, volume = {53}, pages = {R27-R30}, abstract = {We have measured the index of refraction in the region of a coherent population trapping resonance in a cesium vapor cell with an interferometric technique. We find very high normal dispersion (up to dn/df=9.7x10(-12) Hz(-1)) at low absorption. From our spectra we obtain very small group velocities below c/3000. This corresponds to a delay time of more than 200 ns for a cesium cell 20 mm in length, equivalent to more than 60 m of propagation in vacuum. } } @ARTICLE{HarrisFK92, author = {Harris, S. E. and Field, J. E. and Kasapi, A.}, title = {Dispersive properties of electromagnetically induced transparency}, journal = {Phys. Rev. A}, year = {1992}, volume = {46}, pages = {R29-R32}, abstract = {An atomic transition that has been made transparent by applying an additional electromagnetic field exhibits a rapidly varying refractive index with zero group velocity dispersion at line center. A 10-cm-long Pb vapor cell at an atom density of 7 x 10(15) atoms/cm3 and probed on its 283-nm resonance transition has a calculated optical delay of 83 ns [(c/V(G)) = 250].} }