Selective Control of the Symmetric Dicke Subspace in Trapped Ions

We propose a method of manipulating selectively the symmetric Dicke subspace in the internal degrees of freedom of N trapped ions. We show that the direct access to ionic-motional subspaces, based on a suitable tuning of motion-dependent AC Stark shifts, induces a two-level dynamics involving previously selected ionic Dicke states. In this manner, it is possible to produce, sequentially and unitarily, ionic Dicke states with increasing excitation number. Moreover, we propose a probabilistic technique to produce directly any ionic Dicke state assuming suitable initial conditions.Comment: 5 pages and 1 figure. New version with minor changes and added references. Accepted in Physical Review

Effective Quantum Dynamics of Interacting Systems with Inhomogeneous Coupling

We study the quantum dynamics of a single mode/particle interacting inhomogeneously with a large number of particles and introduce an effective approach to find the accessible Hilbert space where the dynamics takes place. Two relevant examples are given: the inhomogeneous Tavis-Cummings model (e.g., N atomic qubits coupled to a single cavity mode, or to a motional mode in trapped ions) and the inhomogeneous coupling of an electron spin to N nuclear spins in a quantum dot.Comment: 9 pages and 10 figures, new version, accepted in Physical Review

Multipartite Entanglement Generation Assisted by Inhomogeneous Coupling

We show that controllable inhomogeneous coupling between two-level systems and a common data bus provides a fast mechanism to produce multipartite entanglement. Our proposal combines resonant interactions and engineering of coupling strengths---between the qubits and the single mode---leading to well defined entangled states. Furthermore, we show that, if the two-level systems interact dispersively with the quantized mode, engineering of coupling strengths allows the controlled access of the symmetric Hilbert space of qubits.Comment: 5 pages, 4 figures. Submitted for publicatio

Sudden Birth Versus Sudden Death of Entanglement in Multipartite Systems

We study the entanglement dynamics of two cavities interacting with independent reservoirs. Expectedly, we observe that, as the cavity entanglement is depleted, it is transferred to the reservoir degrees of freedom. We find that when the cavity entanglement suddenly disappear, the reservoir entanglement suddenly and necessarily appears. Surprisingly, we show that this {\it entanglement sudden birth} can manifest before, simultaneously, or even after {\it entanglement sudden death}. Finally, we present an explanatory study of other entanglement partitions and of higher dimensional systems.Comment: 5 pages, 5 figures, accepted for publication in Physical Review Letter

Biochemical composition and physicochemical properties of Moringa oleifera seed oil

Moringa oleifera tree has been recognized internationally for its nutritional, therapeutic and medicinal properties. Dry seeds are rich sources of oil with a high potential of commercial exploitation. The present study reports the physicochemical characterization, polyphenol content, DPPH radical scavenging capacity and fatty acid profile of moringa seed oil, and the chemical composition of the seed cultivated in Sonora, Mexico. Moisture, ash, protein and lipid contents in the seed were found to be 4.7, 5.8, 26 and 39%, respectively. The oil showed a refractive index of 1.4642. The saponification number was 183 mg KOH/g oil, iodine value: 75 g I/100 g of oil, acid value: 0.49 (% oleic acid). The polyphenol content was 0.137 mg of gallic acid equivalent/g and DPPH radical scavenging capacity was 87.39%. The moringa seed oil was rich (68%) in the major fatty acid, oleic acid (C18:1n9). Moringa oil extracted by sonication showed a fatty acid profile and physicochemical properties comparable to the oil from seeds grown in different regions of the world. The optimization of the oil extraction process on a large scale shows high potential, as the oil could be marketed as edible vegetable oil, for frying purposes, or as a functional ingredient

Negative pressures in CaWO4 nanocrystals

Tetragonal scheelite-type CaWO4 nanocrystals recently prepared by a hydrothermal method show an enhancement of its structural symmetry with the decrease in nanocrystal size. The analysis of the volume dependence of the structural parameters in CaWO4 nanocrystals with the help of ab initio total-energy calculations shows that the enhancement of the symmetry in the scheelite-type nanocrystals is a consequence of the negative pressure exerted on the nanocrystals; i.e., the nanocrystals are under tension. Besides, the behavior of the structural parameters in CaWO4 nanocrystals for sizes below 10 nm suggests an onset of a scheelite-to-zircon phase transformation in good agreement with the predictions from our ab initio calculations. CaWO4 nanocrystals exhibit a reconstructive-type mechanism for the scheelite-to-zircon phase transition that seems to follow the tetragonal path that links both structures. This result is in contrast with the mechanism recently proposed for this transition in bulk ZrSiO4 where the transition goes through an intermediate monoclinic [email protected]

Low Cost Semi Automated Assembly Unit for Small Size Back Contact Modules and Low Cost Interconnection Approach

AbstractWe present our low cost assembly unit to manufacture back contact solar modules based on the conductive backsheet (CBS) approach. This in house developed apparatus was built to assemble test modules containing one up to four 6 inch back contact solar cells. The system is a retrofit of a commercially available CNC system which is equipped with a cell grabber and a manual dispensing system (by Nordson). The total cost of the setup was roughly 4000 € excluding the dispenser unit. Using this equipment we assembled several small size modules containing one and four Zebra cells, which are low cost 6 inch IBC solar cells developed at ISC Konstanz [1,2]. The contact between copper backsheet and back contact cell of the one cell modules we present here is formed by low temperature solder paste (LTSP). First cell to module (CTM) loss evaluations and reliability results suggest that this material could be a viable alternative to electrically conductive adhesive (ECA) which is currently the most commonly used material for this purpose

High-pressure study of ScVO4 by Raman scattering and ab initio calculations

We report results of experimental and theoretical lattice-dynamics studies on scandium orthovanadate up to 35 GPa. Raman-active modes of the low-pressure zircon phase are measured up to 8.2 GPa, where the onset of an irreversible zircon-to-scheelite phase transition is detected. Raman-active modes in the scheelite structure are observed up to 16.5 GPa. Beyond 18.2 GPa we detected a gradual splitting of the Eg modes of the scheelite phase, indicating the onset of a second phase transition. Raman symmetries, frequencies, and pressure coefficients in the three phases of ScVO4 are discussed in the light of ab initio lattice-dynamics calculations that support the experimental results. The results on all the three phases of ScVO4 are compared with those previously reported for related orthovanadates.We acknowledge the financial support of the Spanish MCYT under Grants No. MAT2007-65990-C03-01/03, No. MAT2010-21270-C04-01/03/04, and No. CSD2007-00045, and the computation time provided by the Red Espanola de Supercomputacion and the supercomputer Atlante. F.J.M. acknowledges also financial support from "Vicerrectorado de Innovacion y Desarrollo de la UPV" (No. PAID-05-2009 through Project No. UPV2010-0096). Some of the authors are members of the MALTA Consolider Team.Panchal, V.; Manjón Herrera, FJ.; Errandonea, D.; Rodriguez-Hernandez, P.; López-Solano, J.; Muñoz, A.; Achary, S.... (2011). High-pressure study of ScVO4 by Raman scattering and ab initio calculations. Physical Review B. 83(6):641111-1-64111-10. https://doi.org/10.1103/PhysRevB.83.064111S641111-164111-10836Shafi, S. P., Kotyk, M. W., Cranswick, L. M. D., Michaelis, V. K., Kroeker, S., & Bieringer, M. (2009). In Situ Powder X-ray Diffraction, Synthesis, and Magnetic Properties of the Defect Zircon Structure ScVO4−x. Inorganic Chemistry, 48(22), 10553-10559. doi:10.1021/ic900927jMullica, D. F., Sappenfield, E. L., Abraham, M. M., Chakoumakos, B. C., & Boatner, L. A. (1996). Structural investigations of several LnVO4 compounds. Inorganica Chimica Acta, 248(1), 85-88. doi:10.1016/0020-1693(95)04971-1Errandonea, D., & Manjón, F. J. (2008). Pressure effects on the structural and electronic properties of ABX4 scintillating crystals. Progress in Materials Science, 53(4), 711-773. doi:10.1016/j.pmatsci.2008.02.001Aldred, A. T. (1984). Cell volumes of APO4, AVO4, and ANbO4 compounds, where A = Sc, Y, La–Lu. Acta Crystallographica Section B Structural Science, 40(6), 569-574. doi:10.1107/s0108768184002718Errandonea, D., Lacomba-Perales, R., Ruiz-Fuertes, J., Segura, A., Achary, S. N., & Tyagi, A. K. (2009). High-pressure structural investigation of several zircon-type orthovanadates. Physical Review B, 79(18). doi:10.1103/physrevb.79.184104López-Solano, J., Rodríguez-Hernández, P., & Muñoz, A. (2009). Ab initiostudy of high-pressure structural properties of the LuVO4and ScVO4zircon-type orthovanadates. High Pressure Research, 29(4), 582-586. doi:10.1080/08957950903417444Manjón, F. J., Rodríguez-Hernández, P., Muñoz, A., Romero, A. H., Errandonea, D., & Syassen, K. (2010). Lattice dynamics ofYVO4at high pressures. Physical Review B, 81(7). doi:10.1103/physrevb.81.075202Wang, X., Loa, I., Syassen, K., Hanfland, M., & Ferrand, B. (2004). Structural properties of the zircon- and scheelite-type phases ofYVO4at high pressure. Physical Review B, 70(6). doi:10.1103/physrevb.70.064109Klotz, S., Chervin, J.-C., Munsch, P., & Le Marchand, G. (2009). Hydrostatic limits of 11 pressure transmitting media. Journal of Physics D: Applied Physics, 42(7), 075413. doi:10.1088/0022-3727/42/7/075413Errandonea, D., Meng, Y., Somayazulu, M., & Häusermann, D. (2005). Pressure-induced transition in titanium metal: a systematic study of the effects of uniaxial stress. Physica B: Condensed Matter, 355(1-4), 116-125. doi:10.1016/j.physb.2004.10.030Mao, H. K., Xu, J., & Bell, P. M. (1986). Calibration of the ruby pressure gauge to 800 kbar under quasi-hydrostatic conditions. Journal of Geophysical Research, 91(B5), 4673. doi:10.1029/jb091ib05p04673Kresse, G., & Furthmüller, J. (1996). Efficient iterative schemes forab initiototal-energy calculations using a plane-wave basis set. Physical Review B, 54(16), 11169-11186. doi:10.1103/physrevb.54.11169Kresse, G., & Joubert, D. (1999). From ultrasoft pseudopotentials to the projector augmented-wave method. Physical Review B, 59(3), 1758-1775. doi:10.1103/physrevb.59.1758Blöchl, P. E. (1994). Projector augmented-wave method. Physical Review B, 50(24), 17953-17979. doi:10.1103/physrevb.50.17953Perdew, J. P., Burke, K., & Ernzerhof, M. (1996). Generalized Gradient Approximation Made Simple. Physical Review Letters, 77(18), 3865-3868. doi:10.1103/physrevlett.77.3865Mujica, A., Rubio, A., Muñoz, A., & Needs, R. J. (2003). High-pressure phases of group-IV, III–V, and II–VI compounds. Reviews of Modern Physics, 75(3), 863-912. doi:10.1103/revmodphys.75.863Guedes, I., Hirano, Y., Grimsditch, M., Wakabayashi, N., Loong, C.-K., & Boatner, L. A. (2001). Raman study of phonon modes in ErVO4 single crystals. Journal of Applied Physics, 90(4), 1843-1846. doi:10.1063/1.1384858Garg, A. B., Rao, R., Sakuntala, T., Wani, B. N., & Vijayakumar, V. (2009). Phase stability of YbVO4 under pressure: In situ x-ray and Raman spectroscopic investigations. Journal of Applied Physics, 106(6), 063513. doi:10.1063/1.3223327Santos, C. C., Silva, E. N., Ayala, A. P., Guedes, I., Pizani, P. S., Loong, C.-K., & Boatner, L. A. (2007). Raman investigations of rare earth orthovanadates. Journal of Applied Physics, 101(5), 053511. doi:10.1063/1.2437676Zhang, F. X., Wang, J. W., Lang, M., Zhang, J. M., Ewing, R. C., & Boatner, L. A. (2009). High-pressure phase transitions ofScPO4andYPO4. Physical Review B, 80(18). doi:10.1103/physrevb.80.184114Tossell, J. A. (1975). Electronic structures of silicon, aluminum, and magnesium in tetrahedral coordination with oxygen from SCF-X.alpha. MO calculations. Journal of the American Chemical Society, 97(17), 4840-4844. doi:10.1021/ja00850a010Rao, R., Garg, A. B., Sakuntala, T., Achary, S. N., & Tyagi, A. K. (2009). High pressure Raman scattering study on the phase stability of LuVO4. Journal of Solid State Chemistry, 182(7), 1879-1883. doi:10.1016/j.jssc.2009.05.003Duclos, S. J., Jayaraman, A., Espinosa, G. P., Cooper, A. S., & Maines, R. G. (1989). Raman and optical absorption studies of the pressure-induced zircon to scheelite structure transformation in TbVO4 and DyV04. Journal of Physics and Chemistry of Solids, 50(8), 769-775. doi:10.1016/0022-3697(89)90055-3Smirnov, M. B., Mirgorodsky, A. P., Kazimirov, V. Y., & Guinebretière, R. (2008). Bond-switching mechanism for the zircon-scheelite phase transition. Physical Review B, 78(9). doi:10.1103/physrevb.78.094109Flórez, M., Contreras-García, J., Recio, J. M., & Marqués, M. (2009). Quantum-mechanical calculations of zircon to scheelite transition pathways inZrSiO4. Physical Review B, 79(10). doi:10.1103/physrevb.79.104101Rousseau, D. L., Bauman, R. P., & Porto, S. P. S. (1981). Normal mode determination in crystals. Journal of Raman Spectroscopy, 10(1), 253-290. doi:10.1002/jrs.1250100152Mittal, R., Garg, A. B., Vijayakumar, V., Achary, S. N., Tyagi, A. K., Godwal, B. K., … Chaplot, S. L. (2008). Investigation of the phase stability of LuVO4at high pressure using powder x-ray diffraction measurements and lattice dynamical calculations. Journal of Physics: Condensed Matter, 20(7), 075223. doi:10.1088/0953-8984/20/7/075223Manjón, F. J., Errandonea, D., Garro, N., Pellicer-Porres, J., Rodríguez-Hernández, P., Radescu, S., … Muñoz, A. (2006). Lattice dynamics study of scheelite tungstates under high pressure I.BaWO4. Physical Review B, 74(14). doi:10.1103/physrevb.74.144111Manjon, F. J., Errandonea, D., Garro, N., Pellicer-Porres, J., López-Solano, J., Rodríguez-Hernández, P., … Muñoz, A. (2006). Lattice dynamics study of scheelite tungstates under high pressure II.PbWO4. Physical Review B, 74(14). doi:10.1103/physrevb.74.144112Panchal, V., Garg, N., & Sharma, S. M. (2006). Raman and x-ray diffraction investigations on BaMoO4under high pressures. Journal of Physics: Condensed Matter, 18(16), 3917-3929. doi:10.1088/0953-8984/18/16/002Hardcastle, F. D., & Wachs, I. E. (1991). Determination of vanadium-oxygen bond distances and bond orders by Raman spectroscopy. The Journal of Physical Chemistry, 95(13), 5031-5041. doi:10.1021/j100166a025Brown, I. D., & Wu, K. K. (1976). Empirical parameters for calculating cation–oxygen bond valences. Acta Crystallographica Section B Structural Crystallography and Crystal Chemistry, 32(7), 1957-1959. doi:10.1107/s0567740876006869Lacomba-Perales, R., Martinez-García, D., Errandonea, D., Le Godec, Y., Philippe, J., Le Marchand, G., … López-Solano, J. (2010). Experimental and theoretical investigation of the stability of the monoclinicBaWO4-II phase at high pressure and high temperature. Physical Review B, 81(14). doi:10.1103/physrevb.81.144117Tschauner, O., Errandonea, D., & Serghiou, G. (2006). Possible superlattice formation in high-temperature treated carbonaceous MgB2 at elevated pressure. Physica B: Condensed Matter, 371(1), 88-94. doi:10.1016/j.physb.2005.09.042Errandonea, D., Kumar, R. S., Ma, X., & Tu, C. (2008). High-pressure X-ray diffraction study of SrMoO4 and pressure-induced structural changes. Journal of Solid State Chemistry, 181(2), 355-364. doi:10.1016/j.jssc.2007.12.010Errandonea, D., Santamaria-Perez, D., Grover, V., Achary, S. N., & Tyagi, A. K. (2010). High-pressure x-ray diffraction study of bulk and nanocrystalline PbMoO4. Journal of Applied Physics, 108(7), 073518. doi:10.1063/1.3493048Errandonea, D., Santamaria-Perez, D., Bondarenko, T., & Khyzhun, O. (2010). New high-pressure phase of HfTiO4 and ZrTiO4 ceramics. Materials Research Bulletin, 45(11), 1732-1735. doi:10.1016/j.materresbull.2010.06.061Marqués, M., Flórez, M., Recio, J. M., Gerward, L., & Olsen, J. S. (2006). Structure and stability ofZrSiO4under hydrostatic pressure. Physical Review B, 74(1). doi:10.1103/physrevb.74.014104Lacomba-Perales, R., Errandonea, D., Meng, Y., & Bettinelli, M. (2010). High-pressure stability and compressibility ofAPO4(A=La, Nd, Eu, Gd, Er, and Y) orthophosphates: An x-ray diffraction study using synchrotron radiation. Physical Review B, 81(6). doi:10.1103/physrevb.81.064113Long, Y. W., Zhang, W. W., Yang, L. X., Yu, Y., Yu, R. C., Ding, S., … Jin, C. Q. (2005). Pressure-induced structural phase transition in CaCrO4: Evidence from Raman scattering studies. Applied Physics Letters, 87(18), 181901. doi:10.1063/1.2117624Long, Y. W., Yang, L. X., Yu, Y., Li, F. Y., Yu, R. C., Ding, S., … Jin, C. Q. (2006). High-pressure Raman scattering and structural phase transition inYCrO4. Physical Review B, 74(5). doi:10.1103/physrevb.74.054110Errandonea, D., Kumar, R. S., Gracia, L., Beltrán, A., Achary, S. N., & Tyagi, A. K. (2009). Experimental and theoretical investigation ofThGeO4at high pressure. Physical Review B, 80(9). doi:10.1103/physrevb.80.094101Gracia, L., Beltrán, A., & Errandonea, D. (2009). Characterization of theTiSiO4structure and its pressure-induced phase transformations: Density functional theory study. Physical Review B, 80(9). doi:10.1103/physrevb.80.094105Errandonea, D. (2007). Landau theory applied to phase transitions in calcium orthotungstate and isostructural compounds. Europhysics Letters (EPL), 77(5), 56001. doi:10.1209/0295-5075/77/56001Errandonea, D., & Manjón, F. J. (2009). On the ferroelastic nature of the scheelite-to-fergusonite phase transition in orthotungstates and orthomolybdates. Materials Research Bulletin, 44(4), 807-811. doi:10.1016/j.materresbull.2008.09.024Errandonea, D., Pellicer-Porres, J., Manjón, F. J., Segura, A., Ferrer-Roca, C., Kumar, R. S., … Aquilanti, G. (2005). High-pressure structural study of the scheelite tungstatesCaWO4andSrWO4. Physical Review B, 72(17). doi:10.1103/physrevb.72.174106Errandonea, D. (2005). High-pressure X-ray diffraction study of EuWO4 to 12 GPa. physica status solidi (b), 242(14), R125-R127. doi:10.1002/pssb.200541334Begun, G. M., Beall, G. W., Boatner, L. A., & Gregor, W. J. (1981). Raman spectra of the rare earth orthophosphates. Journal of Raman Spectroscopy, 11(4), 273-278. doi:10.1002/jrs.1250110411Podor, R. (1995). Raman spectra of the actinide-bearing monazites. European Journal of Mineralogy, 7(6), 1353-1360. doi:10.1127/ejm/7/6/1353Zhang, C. C., Zhang, Z. M., Dai, R. C., Wang, Z. P., Zhang, J. W., & Ding, Z. J. (2010). High-Pressure Raman and Luminescence Study on the Phase Transition of GdVO4:Eu3+ Microcrystals. The Journal of Physical Chemistry C, 114(42), 18279-18282. doi:10.1021/jp106063cVoron’ko, Y. K., Sobol’, A. A., Shukshin, V. E., Zagumennyĭ, A. I., Zavartsev, Y. D., & Kutovoĭ, S. A. (2009). Raman spectroscopic study of structural disordering in YVO4, GdVO4, and CaWO4 crystals. Physics of the Solid State, 51(9), 1886-1893. doi:10.1134/s1063783409090200Baran, E. J., Escobar, M. E., Fournier, L. L., & Filgueira, R. R. (1981). Die Raman-Spektren der Orthovanadate der Seltenen Erden. Zeitschrift f�r anorganische und allgemeine Chemie, 472(1), 193-199. doi:10.1002/zaac.19814720123Frost, R. L., Henry, D. A., Weier, M. L., & Martens, W. (2006). Raman spectroscopy of three polymorphs of BiVO4: clinobisvanite, dreyerite and pucherite, with comparisons to (VO4)3-bearing minerals: namibite, pottsite and schumacherite. Journal of Raman Spectroscopy, 37(7), 722-732. doi:10.1002/jrs.1499Blin, J. L., Lorriaux-Rubbens, A., Wallart, F., & Wignacourt, J. P. (1996). Synthesis and structural investigation of the Eu1–xBixVO4scheelite phase: X-ray diffraction, Raman scattering and Eu3+luminescence. J. Mater. Chem., 6(3), 385-389. doi:10.1039/jm9960600385Manjón, F. J., Errandonea, D., López-Solano, J., Rodríguez-Hernández, P., & Muñoz, A. (2009). Negative pressures in CaWO4 nanocrystals. Journal of Applied Physics, 105(9), 094321. doi:10.1063/1.3116727Tokunaga, S., Kato, H., & Kudo, A. (2001). Selective Preparation of Monoclinic and Tetragonal BiVO4with Scheelite Structure and Their Photocatalytic Properties. Chemistry of Materials, 13(12), 4624-4628. doi:10.1021/cm0103390Rice, C. E., & Robinson, W. R. (1976). Lanthanum orthovanadate. Acta Crystallographica Section B Structural Crystallography and Crystal Chemistry, 32(7), 2232-2233. doi:10.1107/s0567740876007450Errandonea, D., Manjón, F. J., Somayazulu, M., & Häusermann, D. (2004). Effects of pressure on the local atomic structure of CaWO4 and YLiF4: mechanism of the scheelite-to-wolframite and scheelite-to-fergusonite transitions. Journal of Solid State Chemistry, 177(4-5), 1087-1097. doi:10.1016/j.jssc.2003.10.01