Showing papers on "Electromagnetically induced transparency published in 2000"
TL;DR: This work identifies form-stable coupled excitations of light and matter ("dark-state polaritons") associated with the propagation of quantum fields in electromagnetically induced transparency that can be controlled by an external coherent field as the pulse propagates.
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.
1,314 citations
TL;DR: Ground state laser cooling of a single trapped Ca(+)on is achieved with a technique which tailors the absorption profile for the cooling laser by exploiting electromagnetically induced transparency using the Zeeman structure of the S(1/2) to P(1 /2) dipole transition.
Abstract: Ground state laser cooling of a single trapped Ca(+)on is achieved with a technique which tailors the absorption profile for the cooling laser by exploiting electromagnetically induced transparency. Using the Zeeman structure of the S(1/2) to P(1/2) dipole transition we achieve up to 90% ground state probability. The new method is robust, easy to implement, and proves particularly useful for cooling several motional degrees of freedom simultaneously, which is of great practical importance for the implementation of quantum logic schemes with trapped ions.
222 citations
TL;DR: A laser cooling method for trapped atoms is described which achieves ground state cooling by exploiting quantum interference in a driven Lambda-shaped arrangement of atomic levels and it is shown that a rate equation provides a good approximation.
Abstract: A laser cooling method for trapped atoms is described which achieves ground state cooling by exploiting quantum interference in a driven Lambda-shaped arrangement of atomic levels. The scheme is technically simpler than existing methods of sideband cooling, yet it can be significantly more efficient, in particular when several motional modes are involved, and it does not impose restrictions on the transition linewidth. We study the full quantum mechanical model of the cooling process for one motional degree of freedom and show that a rate equation provides a good approximation.
217 citations
Proceedings Article•
12 May 2000TL;DR: In this article, a simple theoretical model for electromagnetically induced absorption (EIA) was proposed for a four-state N-atom system, where the EIT-resonance with negative sign was obtained only for three-state /spl Lambda/- and V-systems.
Abstract: Summary form only given. It is well-known that nonlinear interference effects in the resonant atom-light interaction can lead to interesting and important phenomena, such as electromagnetically induced transparency (EIT) of atomic medium, coherent population trapping, lasing without inversion, and others. Common to all these phenomena is the appearance of light-induced coherence between atomic levels, which are not coupled by dipole transitions. Recently Akulshin and co-workers (1998-9) have observed subnatural-width resonances in the absorption on the D/sub 2/ line of rubidium vapor under excitation by two copropagating optical waves with variable frequency offset. It is remarkable that, apart from expected EIT-resonances with negative sign, authors detected positive resonances termed as electromagnetically induced absorption (EIA). More recently, similar effects in a (3+5)-state system have been described as a result of constructive interference of the dipole excitation channels. We propose a simple theoretical model for EIA - a four-state N-atom. Remember that three-state /spl Lambda/- and V-systems give the EIT-resonances only.
148 citations
TL;DR: In this paper, an adiabatic technique is proposed to transfer non-classical correlations from traveling-wave single-photon wavepackets into atomic states and vise versa with nearly 100% efficiency.
146 citations
TL;DR: In this paper, a method for all-optical switching and wavelength conversion using electromagnetically induced transparency (EIT) was proposed, and the mechanism for the transfer of information in this scheme was discussed.
Abstract: We propose a method for all-optical switching and wavelength conversion using electromagnetically induced transparency (EIT). We discuss the mechanism for the transfer of information in this scheme and determine the conditions for which N×N wavelength conversion can be realized. We compare the properties and limits of an EIT-based switch to conventional wavelength converters.
130 citations
TL;DR: Cavity-linewidth narrowing in a ring cavity that is due to the high dispersion and reduced absorption produced by electromagnetically induced transparency in rubidium-atom vapor has been experimentally observed.
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.
119 citations
TL;DR: In this article, the authors analyze systematic and fundamental limitations of the sensitivity of optical magnetometers resulting from ac-Stark shifts. And they demonstrate that an EIT-based optical magnetometer in Faraday configuration is the best candidate to achieve the highest sensitivity of magnetic field detection.
Abstract: We analyze systematic (classical) and fundamental (quantum) limitations of the sensitivity of optical magnetometers resulting from ac-Stark shifts. We show that incontrast to absorption-based techniques, the signal reduction associated with classical broadening can be compensated in magnetometers based on phase measurements using electromagnetically induced transparency (EIT). However due to ac-Stark associated quantum noise the signal-to-noise ratio of EIT-based magnetometers attains a maximum value at a certain laser intensity. This value is independent on the quantum statistics of the light and defines a standard quantum limit of sensitivity. We demonstrate that an EIT-based optical magnetometer in Faraday configuration is the best candidate to achieve the highest sensitivity of magnetic field detection and give a detailed analysis of such a device.
99 citations
TL;DR: In this paper, slow light generated by electromagnetically induced transparency is extremely susceptible with respect to Doppler detuning, and therefore, slow light gyroscopes should have ultrahigh sensitivity.
Abstract: Slow light generated by electromagnetically induced transparency is extremely susceptible with respect to Doppler detuning. Consequently, slow-light gyroscopes should have ultrahigh sensitivity.
98 citations
TL;DR: In this paper, it was shown that a system described by two dipole moments exhibits coherent superpositions of internal states that can be completely decoupled from the dissipative interactions and an external driving laser field.
Abstract: We show that an arbitrary system described by two dipole moments exhibits coherent superpositions of internal states that can be completely decoupled fi om the dissipative interactions (responsible for decoherence) and an external driving laser field. These superpositions, known as dark or trapping states, can he completely stable or can coherently interact with the remaining states. We examine the master equation describing the dissipative evolution of the system and identify conditions for population trapping and also classify processes that can transfer the population to these undriven and nondecaying states. It is shown that coherent transfers are possible only if the two systems are nonidentical, that is the transitions have different frequencies and/or decay rates. in particular, we find that the trapping conditions can involve both coherent and dissipative interactions, and depending on the energy level structure of the system, the population can be trapped in a linear superposition of two or more bare states, a dressed state corresponding to an eigenstate of the system plus external fields or, in some cases. in one of the excited states of the system. A comprehensive analysis is presented of the different processes that are responsible for population trapping, and we illustrate these ideas with three examples of two coupled systems: single V- and Lambda-type three-level atoms and two nonidentical tao-level atoms, which are known to exhibit dark states. We show that the effect of population trapping does not necessarily require decoupling of the antisymmetric superposition from the dissipative interactions. We also find that the vacuum-induced coherent coupling between the systems could be easily observed in Lambda-type atoms. Our analysis of the population trapping in two nonidentical atoms shows that the atoms can be driven into a maximally entangled state which is completely decoupled from the dissipative interaction.
67 citations
TL;DR: In this article, the magnitude dependence of electromagnetically induced transparency on the probe and coupling field polarizations in a three-level cascade scheme in rubidium has been demonstrated, and it is shown that this dependence is due to the presence of the degenerate magnetic sublevels and the strengths of their relative dipole matrix elements.
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.
TL;DR: In this paper, the degenerate Zeeman sublevels are found to play important roles in quantum interference phenomena such as EIT and amplification without population inversion (AWI), and should be taken into account in the analysis of these phenomena.
Abstract: We have observed various $\ensuremath{\Lambda}$-type electromagnetically induced transparency (EIT) spectra in laser-cooled ${}^{87}\mathrm{Rb}$ atoms of different laser polarization configurations. Unexpected profiles occur in the EIT spectra. We have found the degenerate Zeeman sublevels are responsible for these profiles. The experimental data are in good agreement with the results from the theoretical calculation which takes into account all the 13 Zeeman levels in the $\ensuremath{\Lambda}$ system. Our study demonstrates that Zeeman sublevels play important roles in quantum interference phenomena such as EIT and amplification without population inversion (AWI), and should be taken into account in the analysis of these phenomena.
TL;DR: In this article, the authors analyzed nonlinear excitation in a four-level atomic system that exhibits electromagnetically induced transparency induced by a strong coupling laser and showed that, at the line center of the atomic transition, the non-degenerate two-photon excitation can be enhanced by constructive quantum interference in two excitation paths while the linear absorption is inhibited by destructive quantum interference.
Abstract: We analyze nonlinear excitation in a four-level atomic system that exhibits electromagnetically induced transparency induced by a strong coupling laser. We show that, at the line center of the atomic transition, the nondegenerate two-photon excitation in the dressed states can be enhanced by constructive quantum interference in two excitation paths while the linear absorption is inhibited by destructive quantum interference. We report an experimental study of the interference-enhanced two-photon absorption in a multilevel Λ-type rubidium atomic system and compare the measurements with the theoretical calculations.
TL;DR: In this article, a remarkable quenching of the absorption due to electromagnetic-induced transparency in an undoped bulk semiconductor was predicted, and the conditions for its occurrence were determined and numerical estimates for the specific case of the yellow exciton of
Abstract: We predict a remarkable quenching of the absorption due to electromagnetic-induced transparency in an undoped bulk semiconductor. For free-exciton lines the effect is expected to be as large as that observed in atomic systems. The conditions for its occurrence are determined and numerical estimates are presented for the specific case of the yellow exciton of
TL;DR: It is demonstrated 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.
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.
TL;DR: In this paper, the authors demonstrated the phase-locked quantum coherence between three confined electron subband levels in a quantum well which are almost equally spaced in energy by applying a strong coupling field, two-photon-resonant with the 1-3 intersubband transition.
Abstract: The phenomenon of electromagnetically induced quantum coherence is demonstrated between three confined electron subband levels in a quantum well which are almost equally spaced in energy. Applying a strong coupling field, two-photon-resonant with the 1–3 intersubband transition, produces a pronounced narrow transparency feature in the 1–2 absorption line. This result can be understood in terms of all three states being simultaneously driven into “phase-locked” quantum coherence by a single coupling field. We describe the effect theoretically with a density matrix method and an adapted linear response theory. Tuning the excitation laser to the 1–2 absorption energy allows the electron subband momentum distributions to be measured with the sample close to intersubband inversion. These are modelled to yield scattering rates and non-equilibrium phonon densities.
TL;DR: In this article, it was shown that 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.
TL;DR: The nonlinear response of an autoionizing medium in which coherence is established essentially by nonradiative interactions is analyzed and it is found that the third-order nonlinearities can be enhanced while the absorption is canceled.
Abstract: The nonlinear response of an autoionizing medium in which coherence is established essentially by nonradiative interactions is analyzed. It is found that, by proper tuning of two radiation fields, the third-order nonlinearities can be enhanced while the absorption is canceled. The proposed scheme is particularly useful for enhancing nonlinearities in the VUV region.
TL;DR: In this article, an external weak optical field probes the interband transition and pump-induced population redistribution within the conduction subbands in the QW system is investigated based on semiconductor Bloch equations.
Abstract: Optical interband excitonic absorption of semiconductor quantum wells (QW's) driven by a coherent pump field is investigated based on semiconductor Bloch equations. The pump field has a photon energy close to the intersubband spacing between the first two conduction subbands in the QW's. An external weak optical field probes the interband transition. The excitonic effects and pump-induced population redistribution within the conduction subbands in the QW system are included. When the density of the electron-hole pairs in the QW structure is low, the pump field induces an Autler-Townes splitting of the exciton absorption spectrum. The split size and the peak positions of the absorption doublet depend not only on the pump frequency and intensity but also on the carrier density. As the density of the electron-hole pairs is increased, the split contrast (the ratio between the maximum and minimum values) is decreased because the exciton effect is suppressed at higher densities due to the many-body screening.
TL;DR: In this article, the authors examined the effect of electromagnetically induced transparency in a thin cell filled with a vapor of three-level $\ensuremath{\Lambda}$ atoms, and showed that the absorption spectrum of the probe field and the fluorescence signal from the upper atomic level contain two sub-Doppler dips that have considerably different widths.
Abstract: We examine the effect of electromagnetically induced transparency in a thin cell filled with a vapor of three-level $\ensuremath{\Lambda}$ atoms. We show that the absorption spectrum of the probe field and the fluorescence signal from the upper atomic level contain two sub-Doppler dips that have considerably different widths. The narrow dip corresponds to the effect of electromagnetically induced transparency, whereas the broader one results from the optical pumping of the external atomic states. Under the condition of exact resonance of the coupling field with the corresponding atomic transition, these two dips are superimposed on the frequency scale, while in the case of nonzero detuning of the coupling field, the two dips are shifted with respect to each other, which makes it possible to observe a competition between the two effects. In the frequency region where the absorption is low, large optical nonlinearities conditioned merely by the slow atoms having an effective 1 mK temperature are also found.
07 May 2000
TL;DR: There exist periodic femtosecond-time-scale, temporal pulse shapes which propagate without change in shape and self-consistently establish a Raman coherence.
Abstract: Summary form only given. Two laser beams whose frequency difference is close, but not exactly equal, to that of a Raman resonance in a molecular medium will drive the resonance so as to establish a phased and, in effect, propagating molecular coherence. We discuss the conditions for the existence of Raman eigenvectors. These conditions are: (1) In analogy to electromagnetically induced transparency (EIT) in atoms, one must use the anti-phased molecular state. (2) There is a requirement on the magnitude of the Raman polarizability as compared to the background dispersive polarizability. (3) The pulse train as a whole (for example 20-ns long for typical Q-switched lasers) must have an energy which is sufficiently large that the total number of photons is large as compared to the number of molecules in the laser path. When these conditions are satisfied, also in analogy to EIT, the Raman coherence is self-consistently prepared by pulses in the front of the pulse train.
TL;DR: In this paper, a detailed numerical analysis based upon the Maxwell propagation equations is presented, showing that the signal behavior strongly depends on the frequency difference between the probe beam and the coupling beam.
Abstract: Transmissivity of up to 200% has been observed in an absorption imaging study of electromagnetically induced transparency in cold sodium atoms, when a focused coupling beam is applied near the edge of the atom cloud. The signal behavior strongly depends on the frequency difference between the probe beam and the coupling beam. Such high transmissivity can be attributed to the strong focusing effect of the probe beam, when it propagates in a medium with spatially inhomogeneous refractive index induced by the coupling beam. A detailed numerical analysis based upon the Maxwell propagation equations is presented.
TL;DR: In this article, a new scheme of hole-burning where a strong coherent field makes an Electromagnetically Induced Transparency (EIT) window, could make more or disappearance of hole burning in a Doppler broadening medium under different conditions.
TL;DR: The theory of electromagnetically induced transparency (EIT) in a plasma [S. E. Harris, Phys. Rev. 77, 5357 (1996)] is examined in the context of an infinite system as mentioned in this paper.
Abstract: The theory of electromagnetically induced transparency (EIT) in a plasma [S. E. Harris, Phys. Rev. Lett. 77, 5357 (1996)] is examined in the context of an infinite system. A new dispersion relation is derived which accounts for relativistic effects in an overdense plasma. Several branches of the dispersion relation are plotted and discussed. Particle simulations are used to confirm the findings.
TL;DR: In this paper, the authors studied the effect of probe-to-drive frequency ratio R close to half-integer values for a probe travelling-wave (TW) laser field in closed Doppler-broadened three-level systems driven by a resonant standing-wave laser field of moderate intensity.
Abstract: We study electromagnetically induced transparency for a probe travelling-wave (TW) laser field in closed Doppler-broadened three-level systems driven by a resonant 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 only 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 driving in inducing probe transparency. As an example, we consider parameters for a real closed cascade scheme in barium atoms with R 1.5 showing that probe transmission values of 50% are possible for cases in which the transmission is almost negligible either without driving field or with only one of the TW components of the drive.
12 May 2000
TL;DR: In this article, the authors developed a model based on approximate but plausible arguments to explain these observations and derived an analytic expression for the group velocity of light in a cold gas for two cases: atoms confined in a box and by a harmonic potential.
Abstract: Summary form only given. In the context of Bose-Einstein condensation in atomic gases, the scattering of light from a cold gas is an open front of investigation, both on the theoretical and experimental side. As much as it regards the propagation of radiation inside a cold gas, it is well known that the transmission of resonant light is almost zero. However, electromagnetic induced transparency has been proved to allow the propagation of a light pulse by means of quantum coherence between different internal atomic levels. In this context L.V. Hau et al. (1999) discovered a remarkable property of pulse propagation in a Bose condensate. These authors demonstrated the slowing down of the group velocity of the pulse to 17 m/sec and shown a definite dependence of the group velocity on the temperature of the cold sample. We develop a model based on approximate but plausible arguments to explain these observations. We solve the Maxwell-Bloch equations for a gas of non-interacting bosons initially in thermal equilibrium and derive an analytic expression for the group velocity of light in a cold gas for two cases: atoms confined in a box and by a harmonic potential. We obtain results which reproduce those of Hau et al. for temperatures above the critical value. In particular, the treatment brings out the factors playing the key role in the temperature dependence. We show that the variation of the spatial density of atoms with the temperature is the major factor responsible for the temperature dependence of the group velocity.
TL;DR: In this article, the authors present theoretical work on how microwave induced transparency can be achieved in both Doppler and non-Doppler broadened systems, and demonstrate the feasibility and practical difficulties of such an experiment by considering the specific example of atomic rubidium.
Abstract: In recent years the idea of electromagnetically induced transparency in atomic systems using a microwave coupling field has been discussed. We present theoretical work on how this may be achieved in both Doppler systems, and by extension in non-Doppler broadened systems. By considering the specific example of atomic rubidium we demonstrate the feasibility and practical difficulties of such an experiment. By considering systems with appropriate rotational-vibration structure we conclude that microwave induced transparency in gas vapours is more readily achievable in molecular systems.