Jenny Jouin

Unusual structural-disorder stability of mechanochemically derived-Pb(Sc0.5Nb0.5)O3

This study demonstrates the important effect of processing on the B-site ordering in Pb(Sc0.5Nb0.5)O3 ceramics. In contradiction to previous observations on ceramics prepared from solid state synthesis powders, which show a distinctive B-site cation ordering when annealed below ∼1200 °C, in mechanochemically derived ceramics sintered 200 °C below this temperature, we do not observe such ordering, regardless of the conditions of thermal post-annealing. Accordingly, atomic-scale transmission electron microscopy revealed nanometer-sized B-site ordered regions in mechanochemically derived ceramics contrary to the larger regions extending through the whole grains in solid-state derived ceramics.

Ground-state atomic polarization relaxation-time measurement of Rb filled hypocycloidal core-shaped Kagome HC-PCF

We report on the measurement of ground state atomic polarization relaxation tile of Rb vapor confined in five different hypocycloidal core shape Kagome hollow core photonic crystal fibers made with uncoated silica glass. We are able to distinguish between wall-collision and transit-time effects in optical waveguide and deduce the contribution of the atoms dwell time at the core wall surface. In contrast with convetional macroscopic atomic cell configuration, and in agreement with Monte Carlo simulations, the measured relaxation times were found to be at least one order of magnitude longer than the limit set by the atom-wall collisional relaxation from thermal atoms. This extended relaxation time is explained by the combination of a stronger contribution of the slow atoms in the atomic polarization build-up, and of the relatively significant contribution of dwell time to the relaxation process of the ground state polarization.

Extended Duration of Rubidium Vapor in Aluminosilicate Ceramic Coated Hypocycloidal Core Kagome HC-PCF

Rubidium vapor is loaded into hypocycloidal core shaped Kagome hollow-core photonic crystal fiber (HC-PCF) with the wall of its inner core coated with aluminosilicate ceramic (sol-gel). We show that the presence of Rb vapor is maintained for a longer duration when compared to uncoated Kagome HC-PCF. Rb vapor within the hollow-core of a sol-gel coated Kagome HC-PCF is preserved for over 500 h after the source of Rb is halted. And Rb vapor is detected in the sol-gel coated HC-PCF for more than 80 h after the background Rb vapor signal is no longer observed.

Progress towards atomic vapor photonic microcells: Coherence and polarization relaxation measurements in coated and uncoated HC-PCF

We report a comparative study on dephasing mechanisms between inner core coated and uncoated sections of the same Kagome hypocycloid-shaped core hollow core photonic crystal fibers (HC-PCF) filled with rubidium vapor. The comparison is performed by measuring the atomic polarization relaxation and electromagnetically induced transparency (EIT) linewidth in Rb loaded polydimethylsiloxane (PDMS) inner wall coated and bare silica core Kagome HC-PCF. The measurements show a polarization relaxation time of 32μs in a PDMS coated Kagome HC-PCF and 24μs in uncoated Kagome HC-PCF. A minimum EIT linewidth of 6.2±0.8MHz is achieved in PDMS coated Kagome HC-PCF, and 8.3±0.9 MHz for the uncoated Kagome HC-PCF.

Single laser-beam generated sub-Doppler transparencies in Rb-filled Kagome HC-PCF

There is growing interest in using Hollow-core photonic crystal fiber (HC-PCF) in atomic based laser metrology and quantum optics [1]. Atom-filled HC-PCF represents a compact atomic vapour cell, which thanks to its long light-matter interaction distance enhances spectroscopic feature contrasts and optical nonlinearities. These advantages make atom-filled HC-PCF an outstanding candidate for numerous applications such as miniature atomic clocks, magnetometers, single photon sources, Rydberg-blockade based NOT gates, atom-light entanglement etc [1-4]. Furthermore, the small geometric core size of HC-PCF (5 to 100 μm) and large inner wall surface volume enhance atom-surface effects like physicochemical processes, surface material adsorption, Van der Waals (VW) interaction and Casimir Polder forces, which play a significant role in spectroscopic features that strongly differ from the conventional macroscopic vapor cells. Here we report on experimental observation of wall surface induced sub-Doppler transparencies in Rb-filled Kagome HC-PCF, which dramatically contrast with conventional sub-Doppler transparencies generated techniques (e.g. SAS, EIT). The present transparencies are generated by using one single laser beam injected into Rb loaded Kagome HC-PCF.

Local structure and oxide-ion conduction mechanism in apatite-type lanthanum silicates

Abstract The local structure of apatite-type lanthanum silicates of general formula La9.33+x(SiO4)6O2+3x/2 has been investigated by combining the atomic pair distribution function (PDF) method, conventional X-ray and neutron powder diffraction (NPD) data and density functional theory (DFT) calculations. DFT was used to build structure models with stable positions of excess oxide ions within the conduction channel. Two stable interstitial positions were obtained in accordance with literature, the first one located at the very periphery of the conduction channel, neighbouring the SiO4 tetrahedral units, and the second one closer to the channel axis. The corresponding PDFs and average structures were then calculated and tested against experimental PDFs obtained by X-ray total scattering and NPD Rietveld refinements results gathered from literature. It was shown that of the two stable interstitial positions obtained with DFT only the second one located within the channel is consistent with experimental data. This result consolidates one of the two main conduction mechanisms along the c-axis reported in the literature, namely the one involving cooperative movement of O4 and Oi ions.

Ground-state population relaxation dynamics of polarized Rb atoms in Kagome HC-PCF

We polarized ground-state population thermal-Rb in inner-wall core-coated and uncoated Kagome HC-PCFs and measured its relaxation-time rate and its dependence with the pumping-laser intensity and detuning. Enhancement in relaxation-time in coated fibers is observed.

Long rubidium vapor lifetime in aluminosilicate sol-gel coated hypocycloidal core shape kagome HC-PCF

We present aluminosilicate sol-gel coated rubidium-vapor loaded hollow core kagome fiber. We show experimentally that the rubidium vapor is preserved within the hollow core for greater than 500 hours with no vapor-source.

Atomic polarization relaxation time measurement of Rb filled hypocycloidal core shape Kagome HC-PCF

We measured atomic polarization relaxation-time in PDMS coated and uncoated rubidium-loaded hypocycloidal-core Kagome HC-PCF. The measured relaxation-times of 32μs and 24μs in PDMS coated and uncoated fibers are longer two-orders-of-magnitude than the wall-collision-limited relaxation time.