Experimental verification of a fully inseparable tripartite continuous-variable state

A continuous-variable tripartite entangled state is experimentally generated by combining three independent squeezed vacuum states and the variances of its relative positions and total momentum are measured. We show that the measured values violate the separability criteria based on the sum of these quantities and prove the full inseparability of the generated state.Comment: 5 pages, 4 figure

Criteria for the experimental observation of multi-dimensional optical solitons in saturable media

Criteria for experimental observation of multi-dimensional optical solitons in media with saturable refractive nonlinearities are developed. The criteria are applied to actual material parameters (characterizing the cubic self-focusing and quintic self-defocusing nonlinearities, two-photon loss, and optical-damage threshold) for various glasses. This way, we identify operation windows for soliton formation in these glasses. It is found that two-photon absorption sets stringent limits on the windows. We conclude that, while a well-defined window of parameters exists for two-dimensional solitons (spatial or spatiotemporal), for their three-dimensional spatiotemporal counterparts such a window \emph{does not} exist, due to the nonlinear loss in glasses.Comment: 8 pages, to appear in Phys. Rev.

High pressure evolution of Fe2_{2}O3_{3} electronic structure revealed by X-ray absorption

We report the first high pressure measurement of the Fe K-edge in hematite (Fe$_2$O$_3$) by X-ray absorption spectroscopy in partial fluorescence yield geometry. The pressure-induced evolution of the electronic structure as Fe$_2$O$_3$ transforms from a high-spin insulator to a low-spin metal is reflected in the x-ray absorption pre-edge. The crystal field splitting energy was found to increase monotonically with pressure up to 48 GPa, above which a series of phase transitions occur. Atomic multiplet, cluster diagonalization, and density-functional calculations were performed to simulate the pre-edge absorption spectra, showing good qualitative agreement with the measurements. The mechanism for the pressure-induced phase transitions of Fe$_2$O$_3$ is discussed and it is shown that ligand hybridization significantly reduces the critical high-spin/low-spin pressure.Comment: 5 pages, 4 figures and 1 tabl

Detection of abundant solid methanol toward young low mass stars

We present detections of the absorption band at 3.53 micron due to solid methanol toward three low-mass young stellar objects located in the Serpens and Chameleon molecular cloud complexes. The sources were observed as part of a large spectroscopic survey of ~40 protostars. This is the first detection of solid methanol in the vicinity of low mass (M <1 Msol) young stars and shows that the formation of methanol does not depend on the proximity of massive young stars. The abundances of solid methanol compared to water ice for the three sources are in the range 15-25% which is comparable to those for the most methanol-rich massive sources known. The presence of abundant methanol in the circumstellar environment of some low mass young stars has important consequences for the formation scenarios of methanol and more complex organic species near young solar-type stars.Comment: Accepted for publication in A&A letter

Inelastic X-Ray Scattering Study of Exciton Properties in an Organic Molecular crystal

Excitons in a complex organic molecular crystal were studied by inelastic x-ray scattering (IXS) for the first time. The dynamic dielectric response function is measured over a large momentum transfer region, from which an exciton dispersion of 130 meV is observed. Semiempirical quantum chemical calculations reproduce well the momentum dependence of the measured dynamic dielectric responses, and thus unambiguously indicate that the lowest Frenkel exciton is confined within a fraction of the complex molecule. Our results demonstrate that IXS is a powerful tool for studying excitons in complex organic molecular systems. Besides the energy position, the IXS spectra provide a stringent test on the validity of the theoretically calculated exciton wave functions.Comment: 4 pages, 4 figure

Determining the in-plane orientation of the ground-state orbital of CeCu2Si2

We have successfully determined the hitherto unknown sign of the B44 Stevens crystal-field parameter of the tetragonal heavy-fermion compound CeCu2Si2 using vector q dependent non-resonant inelastic x-ray scattering (NIXS) experiments at the cerium N4,5 edge. The observed difference between the two different directions q||[100] and q||[110] is due to the anisotropy of the crystal-field ground state in the (001) plane and is observable only because of the utilization of higher than dipole transitions possible in NIXS. This approach allows us to go beyond the specific limitations of dc magnetic susceptibility, inelastic neutron scattering, and soft x-ray spectroscopy, and provides us with a reliable information about the orbital state of the 4f electrons relevant for the quantitative modeling of the quasi-particles and their interactions in heavy-fermion systems