Emission of photon echoes in a strongly scattering medium

We observe the two- and three-pulse photon echo emission from a scattering powder, obtained by grinding a Pr$^{3+}$:Y$_2$SiO$_5$ rare earth doped single crystal. We show that the collective emission is coherently constructed over several grains. A well defined atomic coherence can therefore be created between randomly placed particles. Observation of photon echo on powders as opposed to bulk materials opens the way to faster material development. More generally, time-domain resonant four-wave mixing offers an attractive approach to investigate coherent propagation in scattering media

Direct observation of rare-earth-host interactions inEr:Y2SiO5

International audienceWe report the direct observation of Er-Y and Er-Si interactions in Er:Y2SiO5 by spin-echo measurements. Modulations in the spin-echo decay of Er3+ ions are due to magnetic interactions between the rare earth and the host nuclear spins. The closest yttrium ions were found to be out of resonance compared to the yttrium ions farther away from the rare earth. This strong “frozen core” effect around the Er3+ ions suggests that the influence of Y3+ ions on the decoherence processes of erbium is weaker than what can be deduced from the yttrium in the bulk

Toward the design of a generic model of interoperability for Siec

International audienceFaced with the need to take into account environmental impacts, life cycle analysis (LCA) should emerge as an engine for innovation and eco-design. It is clear that there are many barriers to their deployment. There is thus a need for tools to facilitate their integration in business projects. These LCA tools must be compatible with different existing information systems. In addition, it is also necessary that the coupling of the different data sources helps to make decisions. This article shows the requirements of the company ACV Plus in terms of interoperability and HCI (Human-computer Interaction) in order to make its Siec software easily adaptable to various business sectors. Different peripheral tools have been developed to define data exchange formats and meet specific needs. This research aims to develop a generic bus in order to have easier process maintenance and avoid costly development for each new situation. Two PhD thesis have focused on the HCI aspects and on interoperability aspects. More generally, our project aims to develop a new system with interoperable design and management tools that can help any customer in the definition of its environmental projects and eco-design

Hyperfine structure and hyperfine coherent properties of praseodymium in single-crystalline La-2(WO4)(3) by hole-burning and photon-echo techniques

We studied the hyperfine structure and hyperfine coherent properties of the H-3(4)(0)-> D-1(2)(0) transition of Pr3+ ions in a tungstate single crystal La-2(WO4)(3) by hole-burning and photon-echo techniques. This work is motivated by the search of an efficient three level Lambda system in this new compound with which we could build up a quantum memory. By nonconventional hole-burning experiments, the ordering of the hyperfine splittings in the H-3(4)(0) ground state and in the D-1(2)(0) excited state is obtained. The hyperfine splittings are thus ordered: 24.6 and 14.9 MHz for the H-3(4)(0) level and 5.0 and 7.3 MHz for the D-1(2)(0) level. The relative and absolute transition strengths of individual hyperfine transitions are determined by comparing absorption strengths and by measuring the Rabi flopping frequency as the transition is coherently driven. Free induction and Raman echo decays give inhomogeneous and homogeneous hyperfine linewidths of 57 +/- 2 and 1.25 +/- 0.1 kHz, respectively

Long coherence lifetime and electromagnetically induced transparency in a highly-spin-concentrated solid

We have studied a rare-earth-doped crystal, Pr3+:La-2(WO4)(3), which exhibits a high magnetic-moment density. Although the latter favors rare-earth dephasing, a nuclear-spin coherence lifetime of 250 mu s has been observed, as well as electromagnetically induced transparency (EIT). This suggests that a broad range of materials could be considered for quantum information applications such as quantum memories for light, where solids are especially attractive. Absorption and dispersion curves are independently in very good agreement with EIT theory. Fano-like profiles have also been observed

Approche du LNE pour la réalisation du kilogramme dans sa nouvelle redéfinition

National audienc

Approche du LNE pour la réalisation du kilogramme dans sa nouvelle redéfinition

National audienc