Cavity-linewidth narrowing by means of electromagnetically induced transparency

Efficient atomic memory using electromagnetically induced absorption

Cavity linewidth engineering from tunneling induced transparency to Autler–Towns splitting

We propose a scheme to demonstrate the existence of optical Peregrine rogue waves and Akhmediev and Kuznetsov-Ma breathers and realize their active control via electromagnetically induced transparency (EIT). The system we suggest is a cold, $\mathrm{\ensuremath{\Lambda}}$-type three-level atomic gas interacting with a probe and a control laser fields and working under EIT condition. We show that, based on EIT with an incoherent optical pumping, which can be used to cancel optical absorption, (1+1)-dimensional optical Peregrine rogue waves, Akhmediev breathers, and Kuznetsov-Ma breathers can be generated with very low light power. In addition, we demonstrate that the Akhmediev and Kuznetsov-Ma breathers in (2+1)-dimensions obtained can be actively manipulated by using an external magnetic field. As a result, these breathers can display trajectory deflections and bypass obstacles during propagation.

The nonlinear and non-local effects in atomic Rydberg media under electromagnetically induced transparency (EIT) make it a versatile platform for fundamental studies and applications in quantum information. In this paper, we study the dynamics of a Rydberg-EIT system in an ensemble that allows for more than one Rydberg excitation in the propagation direction. The density of two-level atoms is such that transient superradiant effects occur. We experimentally observe a cross-over between coherent collective emission (‘flash’) of two-level atoms to a Rydberg dressed regime (‘dressed flash’) under EIT condition. The complex dynamics are characterised using both intensity and time correlation measurements. We show that while steady-state EIT gives a second order correlation g(2) = 0.79 ± 0.04, the Rydberg-dressed flash exhibits anti-bunching down to 0.2 ± 0.04.

Electromagnetically induced transparency (EIT) has been realized in atomic systems, but fulfilling the EIT conditions for artificial atoms made from superconducting circuits is a more difficult task. Here we report an experimental observation of the EIT in a tunable three-dimensional transmon by probing the cavity transmission. To fulfill the EIT conditions, we tune the transmon to adjust its damping rates by utilizing the effect of the cavity on the transmon states. From the experimental observations, we clearly identify the EIT and Autler-Townes splitting (ATS) regimes as well as the transition regime in between. Also, the experimental data demonstrate that the threshold $\Omega_{\rm AIC}$ determined by the Akaike information criterion can describe the EIT-ATS transition better than the threshold $\Omega_{\rm EIT}$ given by the EIT theory.

We report observations of the dynamics of electromagnetically induced transparency (EIT) in a $\ensuremath{\Lambda}$ system when the ground states are Stark shifted. Interactions of this type exhibit large optical nonlinearities called Kerr nonlinearities, and have numerous applications. The EIT Kerr nonlinearity is relatively slow, which is a limiting factor that may make many potential applications impossible. Using rubidium atoms, we observe the dynamics of the EIT Kerr nonlinearity using a Mach-Zehnder interferometer to measure phase modulation of the EIT fields resulting from a pulsed signal beam Stark shifting the ground state energy levels. The rise times and transients agree well with theory.

In this work we present the experimental realization of electromagnetically induced transparency (EIT) in A-type and multi-V-type configurations in a sample of rubidium atoms inside a vapor cell at room temperature. Typical EIT windows are clearly visible in the Doppler- broadened absorption signal of the weak probe beam. The coherent optical pump and probe fields are produced by two tunable low-cost, low-power, continuous-wave (cw), free-running and single mode operated diode laser systems, temperature stabilized and current controlled, tuned to the D2 line of rubidium atoms at 780.2 nm wavelength. The continuum wave and single mode operation of our laser systems are confirmed by direct and saturated absorption spectroscopy techniques. Among other applications, these simple experiments can be used as a low-cost undergraduate laboratory in atomic physics, laser physics, coherent light-atom interaction, and high resolution atomic spectroscopy.

The temperature dependence of electromagnetically induced transparency (EIT) in a Cs atomic vapor cell was investigated. A probe laser beam frequency was scanned around the resonance frequency of the transition line 6S1/2, F = 3 → 6P3/2, F′ = 4 while the coupling beam frequency was locked to the transition line 6S1/2, F = 4→ 6P3/2, F′ = 4. In order to analyze the temperature dependence of the EIT signal quantitatively, we calculated the dispersion slope of the EIT signal at the resonance frequency of the probe beam by taking the 2 derivative of the measured EIT signal. We found that there existed an optimum temperature at which the dispersion slope had a maximum value. This temperature dependence of the EIT signal was well explained by the calculated results considering the Doppler effect and the atomic coherence relaxation due to atomic collisions.

We propose a scheme to construct a two-dimensional Aubry-Andr\'e (AA) model and realize two-dimensional AA localization of light waves via electromagnetically induced transparency (EIT). The system we suggest is a cold, resonant atomic gas with an $N$-type level configuration and interacting with probe, control, assisted, and far-detuned laser fields. We show that under EIT conditions the probe-field envelope obeys a modified nonlinear Schr\"odinger equation with a quasiperiodic potential, which becomes a two-dimensional nonlinear AA model when the system parameters are suitably chosen. The quasiperiodic potential is obtained by the cross-phase modulation of the assisted field and the Stark shift of the far-detuned laser field. In addition, the cubic nonlinearity term appearing in the model is contributed by the self-phase modulation of the probe field. We demonstrate that the system can be used to not only realize various two-dimensional AA localizations of light waves, but also to display nonlinearity and dimensionality effects on the AA localizations.

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.

We present the experimental observations and theoretical calculations of two electromagnetically induced transparency (EIT) windows and an enhanced EIT signal in a four-level tripod system of D1 line of 87Rb atoms. The two EIT dips produced by a strong coupling beam and a weak trigger beam were observed in the absorption spectrum of probe field, when the frequency detuning of the trigger beam was different from that of the coupling beam. When the frequency detuning of the trigger beam was near or equal to that of the coupling beam, the total depth of the EIT dip created by the coupling beam clearly became larger. The experimental measurements were in agreement with theoretical calculations.

We present experimental measurements of the transmission spectrum of an optical cavity coupled with cold Rb atoms and observation of cavity-linewidth narrowing manifested by electromagnetically induced transparency.

Coherent optical processes on Cs D2 line magnetically induced transitions

We present an experimental demonstration of electromagneticallyinduced two-photon transparency (EITT) in room temperaturerubidium vapor. The 8S1/2 to 5P1/2 fluorescence is usedto monitor the 5S1/2(F = 3) to 8S1/2(F = 3) two-photonabsorption near resonance with the intermediate state 5P3/2.A controlling pump laser beam is employed to coherently couplethe 5P3/2 and 5D5/2 states, thus producing two dressedintermediate states which give rise to destructive interferencein the two-photon transition. An induced two-photon transparencyof about 80% has been obtained at resonance; our experimentalfindings are in good agreement with the general theory of Agarwalet al. (Phys. Rev. Lett., 77 (1996) 1039), when theappropriate spectroscopic parameters are used.

Planar InAs/InP quantum-dot microcavities using multilayer SiO2/Ta2O5 Bragg reflectors have been studied in emission. For an eight-pair mirror design, the stop band extends from 700 to 900 meV and the cavity linewidth is ∼500 μeV for emission at 850 meV. Measurements as a function of incident power show quantum-dot saturation behavior, with the emission intensity going to the wetting layer outside the cavity stop band. Saturation behavior at fixed pump power is also observed as a function of decreasing temperature. Dispersion measurements as a function of emission angle show polarization splitting in reasonable agreement with theory.