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Register a new userPhase-dependent double-{Lambda} electromagnetically induced transparency
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We theoretically investigate a double-{Lambda} electromagnetically induced transparency (EIT) system. The property of the double-{Lambda} medium with a closed-loop configuration depends on the relative phase of the applied laser fields. This phase-dependent mechanism differentiates the double-{Lambda} medium from the conventional Kerr-based nonlinear medium, e.g., EIT-based nonlinear medium discussed by Harris and Hau [Phys. Rev. Lett. 82, 4611 (1999)], which depends only on the intensities of the applied laser fields. Steady-state analytical solutions for the phase-dependent system are obtained by solving the Maxwell-Bloch equations. In addition, we discuss efficient all-optical phase modulation and coherent light amplification based on the proposed double-{Lambda} EIT scheme.
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We show that an alkali atom with a tripod electronic structure can yield rich electromagnetically induced transparency phenomena even at room temperature. In particular we introduce double-double electromagnetically induced transparency wherein signal and probe fields each have two transparency windows. Their group velocities can be matched in either the first or second pair of transparency windows. Moreover signal and probe fields can each experience coherent gain in the second transparency windows. We explain using a semi-classical-dressed-picture to connect the tripod electronic structure to a double-Lambda scheme.
Here we present a microscopic model that describes the Electromagnetically Induced Transparency (EIT) phenomenon in the multiple scattering regime. We consider an ensembles of cold three-level atoms, in a $Lambda$ configuration, scattering a probe and a control field to the vacuum modes of the electromagnetic field. By first considering a scalar description of the scattering, we show that the light-mediated long-range interactions that emerge between the dipoles narrow the EIT transparency window for increasing densities and sample sizes. For a vectorial description, we demonstrate that near-field interacting terms can critically affect the atomic population transfer in the Stimulated Raman Adiabatic Passage (STIRAP). This result points out that standard STIRAP-based quantum memories in dense and cold atomic ensembles would not reach efficiency high enough for quantum information processing applications.
Recent years have seen vast progress in the generation and detection of structured light, with potential applications in high capacity optical data storage and continuous variable quantum technologies. Here we measure the transmission of structured light through cold rubidium atoms and observe regions of electromagnetically induced transparency (EIT). We use q-plates to generate a probe beam with azimuthally varying phase and polarisation structure, and its right and left circular polarisation components provide the probe and control of an EIT transition. We observe an azimuthal modulation of the absorption profile that is dictated by the phase and polarisation structure of the probe laser. Conventional EIT systems do not exhibit phase sensitivity. We show, however, that a weak transverse magnetic field closes the EIT transitions, thereby generating phase dependent dark states which in turn lead to phase dependent transparency, in agreement with our measurements.
We study electromagnetically induced transparency (EIT) of a weakly interacting cold Rydberg gas. We show that the onset of interactions is manifest as a depopulation of the Rydberg state and numerically model this effect by adding a density-dependent non-linear term to the optical Bloch equations. In the limit of a weak probe where the depopulation effect is negligible, we observe no evidence of interaction induced decoherence and obtain a narrow Rydberg dark resonance with a linewidth of <600 kHz, limited by the Rabi frequency of the coupling beam
Vector magnetometry was studied using the electromagnetically induced transparency (EIT) with linear $perp$ linear ($lin perp lin$) polarization of the probe and the pump beams in $^{87}Rb$ - $D_2$ transition. The dependence of the EIT on the direction of the quantization axis and the relative orientation of the polarization of the applied electric fields was studied experimentally. We have shown that from the relative strengths of the $sigma$ and $pi$ EIT peaks, the direction of the magnetic field can be found. Moreover from the relative separation between the $sigma$ and $pi$ EIT peaks, the strengths of the magnetic field can be calculated. We have also demonstrated that the EIT peak amplitudes show oscillatory behaviour depending upon the orientation of the laser polarization relative to the magnetic field direction. Using the positions of the maxima and minima, the direction of the magnetic field can be calculated. To understand the experimental observation, a theoretical study has been done numerically considering all the thirteen Zeeman sub-levels. Apart from the numerical model, a toy model has also been considered to obtain an analytical response of the medium considering the velocity distribution. The dependencies of the magnetic field direction and the polarization direction of the electric fields have been explicitly derived in the analytical model. Further the direction of the magnetic field is calculated using the analytical solution. This study can be helpful in order to make an EIT based atomic vector magnetometer at room temperature.
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