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Transport and interaction blockade with ultracold bosonic atoms
http://hdl.handle.net/2268/199369
Title: Transport and interaction blockade with ultracold bosonic atoms
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<br/>Author, co-author: Schlagheck, PeterFri, 01 Jul 2016 12:39:05 GMTTransport and interaction blockade of cold bosonic atoms in a triple-well potential
http://hdl.handle.net/2268/199363
Title: Transport and interaction blockade of cold bosonic atoms in a triple-well potential
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<br/>Author, co-author: Schlagheck, Peter; Malet, Francesc; Cremon, Jonas C.; Reimann, Stephanie M.
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<br/>Abstract: We investigate the transport properties of cold bosonic atoms in a triple-well potential that consists of two large outer wells, which act as microscopic source and drain reservoirs, and a small inner well, which represents a quantum-dot-like scattering region. Such configurations can be realized by optical triple-well lattices generalizing the setup realized in the interaction blockade experiment by Cheinet et al. [Phys. Rev. Lett. 101, 090404 (2008)]. Bias and gate "voltages" are introduced in order, respectively, to tilt the triple-well configuration and to shift the energetic level of the inner well with respect to the outer ones. By means of exact diagonalization considering a total number of 6 atoms in the triple-well potential, we find diamond-like structures for the occurrence of single-atom transport in the parameter space spanned by the bias and gate voltages, in close analogy with the Coulomb blockade in electronic quantum dots. We demonstrate how one can infer the interaction energy in the central well from the distance between the diamonds, and discuss the possibility of realizing single-atom pumping across the quantum dot.Fri, 01 Jul 2016 12:24:50 GMTTransport and interaction blockade of cold bosonic atoms in a triple-well potential
http://hdl.handle.net/2268/199362
Title: Transport and interaction blockade of cold bosonic atoms in a triple-well potential
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<br/>Author, co-author: Schlagheck, Peter; Malet, Francesc; Cremon, Jonas C.; Reimann, Stephanie M.
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<br/>Abstract: We investigate the transport properties of cold bosonic atoms in a triple-well potential that consists of two large outer wells, which act as microscopic source and drain reservoirs, and a small inner well, which represents a quantum-dot-like scattering region. Such configurations can be realized by optical triple-well lattices generalizing the setup realized in the interaction blockade experiment by Cheinet et al. [Phys. Rev. Lett. 101, 090404 (2008)]. Bias and gate "voltages" are introduced in order, respectively, to tilt the triple-well configuration and to shift the energetic level of the inner well with respect to the outer ones. By means of exact diagonalization considering a total number of 6 atoms in the triple-well potential, we find diamond-like structures for the occurrence of single-atom transport in the parameter space spanned by the bias and gate voltages, in close analogy with the Coulomb blockade in electronic quantum dots. We demonstrate how one can infer the interaction energy in the central well from the distance between the diamonds, and discuss the possibility of realizing single-atom pumping across the quantum dot.Fri, 01 Jul 2016 12:14:13 GMTWeak localization with interacting Bose-Einstein condensates
http://hdl.handle.net/2268/199361
Title: Weak localization with interacting Bose-Einstein condensates
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<br/>Author, co-author: Hartmann, Timo; Hartung, Michael; Michl, Josef; Petitjean, Cyril; Urbina, Juan Diego; Wellen, Thomas; Müller, Cord A.; Richter, Klaus; Schlagheck, Peter
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<br/>Abstract: We study the quasi-stationary propagation of Bose-Einstein condensates through two-dimensional mesoscopic scattering geometries that correspond to disorder potentials [1] or to ballistic billiard con nements with chaotic classical dynamics [2]. Our theoretical approach is based on the two-dimensional Gross-Pitaevskii equation, which is numerically integrated in order to determine reflection and transmission probabilities associated with self-consistent stationary scattering states, and which represents the starting point for an analytical description of the scattering process in terms of a nonlinear diagrammatic theory. Both numerically and analytically, we nd that the presence of the atom-atom interaction within the condensate gives rise to signatures of weak antilocalization, i.e. to an inversion of the coherent backscattering peak in disordered systems [1] and to a reduction, instead of an enhancement, of the retro-reflection probability in chaotic billiard geometries [2]. Short-path contributions associated, in particular, with self-retraced trajectories are conjectured to be at the origin of this antilocalization phenomenon.
References:
[1] M. Hartung, T. Wellens, C. A. M uller, K. Richter, and P. Schlagheck, PRL 101, 020603 (2008).
[2] T. Hartmann, J. Michl, C. Petitjean, T. Wellens, J.-D. Urbina, K. Richter, and P. Schlagheck,
Ann. Phys., in press, (arXiv:1112.5603).Fri, 01 Jul 2016 12:04:43 GMTCoherent backscattering in the Fock space of Bose- and Fermi-Hubbard systems
http://hdl.handle.net/2268/199334
Title: Coherent backscattering in the Fock space of Bose- and Fermi-Hubbard systems
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<br/>Author, co-author: Engl, Thomas; Dujardin, Julien; Tisserond, Emilie; Argüelles, Arturo; Richter, Klaus; Urbina, Juan Diego; Schlagheck, Peter
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<br/>Abstract: Coherent backscattering generally refers to a significant and robust enhancement of the average backscattering probability of a wave within a disordered medium, which from a semiclassical point of view arises due to the constructive interference between backscattered trajectories and their time-reversed counterparts. We recently investigated the manifestation of this wave interference phenomenon in the Fock space of a disordered Bose-Hubbard system of finite extent [1], which can potentially be realized using ultracold bosonic atoms within optical lattices. Preparing the atoms in a well-defined Fock state of the lattice and letting the system evolve for a finite time will, for suitable parameters of the system and upon some disorder average over random on-site energies of the lattice, generally give rise to an equidistribution of the occupation probability within the energy shell of the Fock space that corresponds to the initial energy of the system, in accordance with the quantum microcanonical ensemble. We find, however, that the initial state is twice as often encountered as other Fock states with comparable total energy, which is a consequence of coherent backscattering [1].
Most recently, we showed that this phenomenon also arises in spin 1/2 Fermi-Hubbard rings that involve Rashba hopping terms (which combine inter-site hoppings with spin flips and arise from spin-orbit coupling), for which a newly developed semiclassical theory [2] correctly predicts a coherent enhancement of the occupation probabilities of the initial state and its spin-flipped counterpart. Moreover, performing a global spin flip within this Fermi-Hubbard system will give rise to significant spin echo peaks on those two Fock states, which is again a consequence of quantum many-body interference [3]. The semiclassical predictions of these enhancements and peaks are found to be in very good agreement with numerical findings obtained from the exact quantum time evolution within this Fermi-Hubbard system.
References
[1] T. Engl, J. Dujardin, A. Argüelles, P. Schlagheck, K. Richter, and J. D. Urbina, Phys. Rev. Lett. 112, 140403 (2014).
[2] T. Engl, P. Plößl, J. D. Urbina, and K. Richter, Theoretical Chemistry Accounts 133, 1563 (2014).
[3] T. Engl, J. D. Urbina, and K. Richter, arXiv:1409.5684.Fri, 01 Jul 2016 07:29:41 GMTCoherent backscattering in the Fock space of Bose- and Fermi-Hubbard systems
http://hdl.handle.net/2268/199331
Title: Coherent backscattering in the Fock space of Bose- and Fermi-Hubbard systems
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<br/>Author, co-author: Engl, Thomas; Dujardin, Julien; Tisserond, Emilie; Argüelles, Arturo; Richter, Klaus; Urbina, Juan Diego; Schlagheck, Peter
<br/>
<br/>Abstract: Coherent backscattering generally refers to a significant and robust enhancement of the average backscattering probability of a wave within a disordered medium, which from a semiclassical point of view arises due to the constructive interference between backscattered trajectories and their time-reversed counterparts. We recently investigated the manifestation of this wave interference phenomenon in the Fock space of a disordered Bose-Hubbard system of finite extent [1], which can potentially be realized using ultracold bosonic atoms within optical lattices. Preparing the atoms in a well-defined Fock state of the lattice and letting the system evolve for a finite time will, for suitable parameters of the system and upon some disorder average over random on-site energies of the lattice, generally give rise to an equidistribution of the occupation probability within the energy shell of the Fock space that corresponds to the initial energy of the system, in accordance with the quantum microcanonical ensemble. We find, however, that the initial state is twice as often encountered as other Fock states with comparable total energy, which is a consequence of coherent backscattering [1]. Most recently, we showed that this phenomenon also arises in spin 1/2 Fermi-Hubbard rings that involve Rashba hopping terms (which combine inter-site hoppings with spin flips and arise from spin-orbit coupling), for which a newly developed semiclassical theory [2] correctly predicts a coherent enhancement of the occupation probabilities of the initial state and its spin-flipped counterpart. Moreover, performing a global spin flip within this Fermi-Hubbard system will give rise to significant spin echo peaks on those two Fock states, which is again a consequence of quantum many-body interference [3]. The semiclassical predictions of these enhancements and peaks are found to be in very good agreement with numerical findings obtained from the exact quantum time evolution within this Fermi-Hubbard system. [1] T. Engl, J. Dujardin, A. Argüelles, P. Schlagheck, K. Richter, and J. D. Urbina, Phys. Rev. Lett. 112, 140403 (2014). [2] T. Engl, P. Plößl, J. D. Urbina, and K. Richter, Theoretical Chemistry Accounts 133, 1563 (2014). [3] T. Engl, J. D. Urbina, and K. Richter, arXiv:1409.5684.Fri, 01 Jul 2016 07:07:56 GMTCoherent backscattering in the Fock space of a disordered Bose-Hubbard system
http://hdl.handle.net/2268/199329
Title: Coherent backscattering in the Fock space of a disordered Bose-Hubbard system
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<br/>Author, co-author: Engl, Thomas; Dujardin, Julien; Tisserond, Emilie; Argüelles, Arturo; Richter, Klaus; Urbina, Juan Diego; Schlagheck, Peter
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<br/>Abstract: We predict a generic signature of quantum interference in many-body bosonic systems resulting in a coherent enhancement of the average return probability in Fock space [1]. This enhancement is robust with respect to variations of external parameters even though it represents a dynamical manifestation of the delicate superposition principle in Fock space. It is a genuine quantum many-body effect which lies beyond the reach of any mean-field approach. Using a semiclassical approach based on interfering paths in Fock space, we calculate the magnitude of the backscattering peak and its dependence on gauge fields that break time-reversal invariance. We confirm our predictions by comparing them to exact quantum evolution probabilities in Bose-Hubbard models, and discuss their relevance in the context of many-body thermalization. We furthermore propose a specific experimental setup in order to detect this many-body coherent backscattering phenomenon with ultracold bosonic atoms.
[1] T. Engl, J. Dujardin, A. Argüelles, P. Schlagheck, K. Richter, and J. D. Urbina, Phys. Rev. Lett. 112, 140403 (2014).Fri, 01 Jul 2016 07:00:04 GMTProbing the low-frequency vortex dynamics in a nanostructured superconducting strip
http://hdl.handle.net/2268/199147
Title: Probing the low-frequency vortex dynamics in a nanostructured superconducting strip
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<br/>Author, co-author: de Souza Silva, Clecio C.; Raes, Bart; Brisbois, Jérémy; Cabral, L. R. E.; Silhanek, Alejandro; Van de Vondel, Joris; Moshchalkov, Victor V.
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<br/>Abstract: We investigate by scanning susceptibility microscopy the response of a thin Pb strip, with a square array of submicron antidots, to a low-frequency ac magnetic field applied perpendicularly to the film plane. By mapping the local permeability of the sample within the field range where vortices trapped by the antidots and interstitial vortices coexist, we observed two distinct dynamical regimes occurring at different temperatures. At a temperature just below the superconducting transition, T/Tc = 0.96, the sample response is essentially dominated by the motion of highly mobile interstitial vortices. However, at a slightly lower temperature, T/Tc = 0.93, the interstitial vortices freeze up leading to a strong reduction of the ac screening length. We propose a simple model for the vortex response in this system which fits well to the experimental data. Our analysis suggests that the observed switching to the high mobility regime stems from a resonant effect, where the period of the ac excitation is just large enough to allow interstitial vortices to thermally hop through the weak pinning landscape produced by random material defects. This argument is further supported by the observation of a pronounced enhancement of the out-of-phase response at the crossover between both dynamical regimes.Tue, 28 Jun 2016 13:04:50 GMTProbabilistic models of porous materials
http://hdl.handle.net/2268/199141
Title: Probabilistic models of porous materials
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<br/>Author, co-author: Gommes, CédricTue, 28 Jun 2016 11:51:58 GMTSmall-angle scattering and scale-dependent heterogeneity
http://hdl.handle.net/2268/199140
Title: Small-angle scattering and scale-dependent heterogeneity
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<br/>Author, co-author: Gommes, Cédric
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<br/>Abstract: Although small-angle scattering is often discussed qualitatively in terms of material heterogeneity, when it comes to quantitative data analysis this notion becomes somehow hidden behind the concept of correlation function. In the present contribution, a quantitative measure of heterogeneity is defined, it is shown how it can be calculated from scattering data, and its structural significance for the purpose of material characterization is discussed. Conceptually, the procedure consists of using a finite probe volume to define a local average density at any point of the material; the heterogeneity is then quantitatively defined as the fluctuations of the local average density when the probe volume is moved systematically through the sample. Experimentally, it is shown that the so-defined heterogeneity can be estimated by projecting the small-angle scattering intensity onto the form factor of the chosen probe volume. Choosing probe volumes of various sizes and shapes enables one to
comprehensively characterize the heterogeneity of a material over all its relevant length scales. General results are derived for asymptotically small and large probes in relation to the material surface area and integral range. It is also shown that the correlation function is equivalent to a heterogeneity calculated with a probe volume consisting of two points only. The interest of scale-dependent heterogeneity for practical data analysis is illustrated with experimental small-angle X-ray scattering patterns measured on a micro- and mesoporous material, on a gel, and on a semi-crystalline polyethylene sample. Using different types of probes to analyse a given scattering pattern enables one to focus on different structural characteristics of the material, which is particularly useful in the case of hierarchical structures.Tue, 28 Jun 2016 11:47:38 GMTSize-dependent third-order optical nonlinearity of InP nanoparticles colloidal solution
http://hdl.handle.net/2268/199098
Title: Size-dependent third-order optical nonlinearity of InP nanoparticles colloidal solution
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<br/>Author, co-author: Rosso, Vanessa; Loicq, Jerôme; Hens, zeger; Renotte, Yvon; Lion, Yves
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<br/>Abstract: The third order nonlinear optical effect called the optical Kerr effect was studied in InP nanoparticles solutions. The synthesized InP nanoparticles have sizes ranging from 1.5 to 3.5 nm and each sample is characterized by its sizes distribution. The Z-scan technique was used to study nonlinear absorption and refraction. Different lasers were used, hence different nonlinear refraction effects were observed at different wavelengths (532, 633 and 1550 nm) and at different time scales (continuous and femtosecond).Mon, 27 Jun 2016 11:11:20 GMTNatural radioactivity and elemental composition of sands in the Douala region, Littoral of Cameroon Using Portable XRF and HPGe detector
http://hdl.handle.net/2268/199073
Title: Natural radioactivity and elemental composition of sands in the Douala region, Littoral of Cameroon Using Portable XRF and HPGe detector
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<br/>Author, co-author: Guembou Shouop, Cébastien Joel; Ndontchueng Moyo, Maurice; Chene, Grégoire; Strivay, David
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<br/>Abstract: Twenty four sand samples from seven sand quarries alone the Gulf of Guinea, Douala Littoral region of Cameroon, were analyzed using high purity germanium detector and a portable X-ray fluorescence (PXRF) spectrometer. A comprehensive study was conducted to determine the natural radioactivity concentrations and the geological provenience of sand samples from seven different quarries sites of the Douala, a popular city, and its surroundings. The radioactivity investigation was performed by using high resolution gamma-ray spectrometry. From the measured gamma-spectra, the average activity concentrations were determined for 226Ra, 232Th, 40K and 235U for a depth of 5–25 cm. Results of this study were compared to values from other locations around the world. X-ray fluorescence spectrometry (XRF) measurements were performed for the quantitative elemental analysis of the sands, revealing the major, minor and trace elements present in the investigated samples. Reference marine and geological sample are used to check precision and accuracy of the equipment for major and minor components. From XRF experimental results it was possible to estimate the geological provenience of the analyzed sands. These data record the radioactivity background levels in sands and could be used as reference information in Cameroon. The comparison of major (Si, Al), minor (K, Ca,Fe), and trace (Ti, Mn, Zr, Rb, Sr) element ratios was made. The results indicate that the levels of Si and Al can be very helpful in subgroup definition and provide useful clues to the raw materials used for glassmaking in Cameroon.Sun, 26 Jun 2016 21:59:38 GMTPhotoconductivity and photoconversion at a photorefractive thin crystal plate
http://hdl.handle.net/2268/198997
Title: Photoconductivity and photoconversion at a photorefractive thin crystal plate
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<br/>Author, co-author: Frejlich, Jaime; de Oliveira, Ivan; de Araujo, William R.; Carvalho, Jesiel F.; Georges, Marc; Fleury-Frenette, KarlFri, 24 Jun 2016 07:47:47 GMTMagnetic and conversion electron Mössbauer spectral study of amorphous thin films of DyxFe100-x and Dy20Fe80-yCoy
http://hdl.handle.net/2268/198996
Title: Magnetic and conversion electron Mössbauer spectral study of amorphous thin films of DyxFe100-x and Dy20Fe80-yCoy
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<br/>Author, co-author: Fleury-Frenette, Karl; Delwiche, Jacques; Grandjean, Fernande; Vandormael, D.; Long, G. J.
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<br/>Abstract: Amorphous thin films of DyxFe100-x and Dy20Fe80-yCoy, with various x and y values and of ∼40 nm thickness, have been prepared by sputtering on polyimide films. Their magnetization curves and the Mössbauer spectra indicate that at 295 K the iron moments are preferentially oriented parallel to the film in Dy2Fe98 and that Dy6Fe94 is paramagnetic. The DyxFe100-x thin films, where x is 17, 20, 24, 29, 32, 35, and 37, show perpendicular magnetic anisotropies and moderate coercive fields of at most 150 kA/m, whereas the Dy20Fe80-yCoy thin films, where y is 8, 13, 16, and 20, thin films show stronger perpendicular anisotropies and larger coercive fields of ∼400 kA/m. The introduction of cobalt into the amorphous thin films increases their coercive field and the perpendicular magnetic anisotropy. The Mössbauer spectra of the DyxFe100-x and Dy20Fe80-yCoy amorphous thin films consist of broadened sextets which have been analyzed with a distribution of hyperfine fields by assuming that the iron moments are oriented perpendicular to the plane of the film. Detailed fits of the Mössbauer spectrum of Dy20Fe80 indicate that the cone angle of the iron magnetic moments cannot be determined with accuracy. The average hyperfine fields in the DyxFe100-x amorphous thin films are smaller than those in the crystalline dysprosium-iron intermetallic compounds. The average hyperfine field increases from ∼140 kOe in the DyxFe100-x films to ∼220 kOe in the Dy20Fe80-yCoy films, an increase which is in agreement with the increase in the saturation magnetization. The x dependence of the isomer shift indicates that there is strong dysprosium-iron bonding, whereas the y dependence of the isomer shift reveals an enhancement of the d-electron localization. From earlier x-ray magnetic circular dichroism results and the Mössbauer spectral results presented herein, iron magnetic moments of 0.87 or 0.67 μB, corresponding to 2.9 or 2.8 holes in the iron 3d band, have been obtained for the DyxFe100-x amorphous thin films with x greater or smaller than 27, respectivelyFri, 24 Jun 2016 07:16:53 GMTBases physiques de la scintigraphie et de la tomographie à émissions de positons par Maryse HOEBEKE (ULg)
http://hdl.handle.net/2268/198914
Title: Bases physiques de la scintigraphie et de la tomographie à émissions de positons par Maryse HOEBEKE (ULg)
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<br/>Author, co-author: Hoebeke, Maryse
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<br/>Abstract: Cette conférence avait pour but d'illustrer des applications intéressantes dans le cadre de l'enseignement de la physique nucléaire dans le secondaire
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<br/>Commentary: This conference was designed to illustrate interesting applications of physics in the course of nuclear physics to the attention of secondaryThu, 23 Jun 2016 09:55:48 GMTElectric Field Control of Jahn-Teller Distortions in Bulk Perovskites
http://hdl.handle.net/2268/198911
Title: Electric Field Control of Jahn-Teller Distortions in Bulk Perovskites
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<br/>Author, co-author: Varignon, Julien; Bristowe, Nicholas; Ghosez, Philippe
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<br/>Abstract: The Jahn-Teller distortion, by its very nature, is often at the heart of the various electronic properties displayed by perovskites and related materials. Despite the Jahn-Teller mode being nonpolar, we devise and demonstrate, in the present Letter, an electric field control of Jahn-Teller distortions in bulk perovskites. The electric field control is enabled through an anharmonic lattice mode coupling between the Jahn-Teller distortion and a polar mode. We confirm this coupling and quantify it through first-principles calculations. The coupling will always exist within the Pb21m space group, which is found to be the favored ground state for various perovskites under sufficient tensile epitaxial strain. Intriguingly, the calculations reveal that this mechanism is not only restricted to Jahn-Teller active systems, promising a general route to tune or induce novel electronic functionality in perovskites as a whole.Thu, 23 Jun 2016 09:48:26 GMTSpectral statistics of chaotic many-body systems
http://hdl.handle.net/2268/198855
Title: Spectral statistics of chaotic many-body systems
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<br/>Author, co-author: Dubertrand, Rémy
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<br/>Abstract: We derive a trace formula that expresses the level density of chaotic many-body systems as a smooth term plus a sum over contributions associated to solutions of the nonlinear Schrödinger (or Gross–Pitaevski) equation. Our formula applies to bosonic systems with discretised positions, such as the Bose–Hubbard model, in the semiclassical limit as well as in the limit where the number of particles is taken to infinity. We use the trace formula to investigate the spectral statistics of these systems, by studying interference between solutions of the nonlinear Schrödinger equation. We show that in the limits taken the statistics of fully chaotic many-particle systems becomes universal and agrees with predictions from the Wigner–Dyson ensembles of random matrix theory. The conditions for Wigner–Dyson statistics involve a gap in the spectrum of the Frobenius–Perron operator, leaving the possibility of different statistics for systems with weaker chaotic properties.Wed, 22 Jun 2016 13:00:04 GMTOrigin of emission from square-shaped organic microlasers
http://hdl.handle.net/2268/198853
Title: Origin of emission from square-shaped organic microlasers
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<br/>Author, co-author: Dubertrand, Rémy
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<br/>Abstract: The emission from open cavities with non-integrable features remains a challenging problem of practical as well as fundamental relevance. Square-shaped dielectric microcavities
provide a favorable case study with generic implications for other polygonal resonators. We report on a joint experimental and theoretical study of square-shaped organic microlasers exhibiting a far-field emission that is strongly concentrated in the directions parallel to the side walls of the cavity. A semiclassical model for the far-field distributions is developed that is in agreement with even fine features of the experimental findings. Comparison of the model calculations with the experimental data allows the precise identification of the lasing modes and their emission mechanisms, providing strong support for a physically intuitive ray-dynamical interpretation. Special attention is paid to the role of diffraction and the finite side length.Wed, 22 Jun 2016 12:48:16 GMTUniversal amorphous-amorphous transition in GexSe100−x glasses under pressure
http://hdl.handle.net/2268/198838
Title: Universal amorphous-amorphous transition in GexSe100−x glasses under pressure
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<br/>Author, co-author: Yildirim, Can; Micoulaut, Matthieu; Boolchand, Punit; Kantor, Innokenty; Mathon, Olivier; Gaspard, Jean-Pierre; Irifune, Tetsuo; Raty, Jean-Yves
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<br/>Abstract: Pressure induced structural modifications in vitreous GexSe100−x (where 10 ≤ x ≤ 25) are investigated using X-ray absorption spectroscopy (XAS) along with supplementary X-ray diffraction (XRD) experiments and ab initio molecular dynamics (AIMD) simulations. Universal changes in distances and angle distributions are observed when scaled to reduced densities. All compositions are observed to remain amorphous under pressure values up to 42 GPa. The Ge-Se interatomic distances extracted from XAS data show a two-step response to the applied pressure; a gradual decrease followed by an increase at around 15–20 GPa, depending on the composition. This increase is attributed to the metallization event that can be traced with the red shift in Ge K edge energy which is also identified by the principal peak position of the structure factor. The densification mechanisms are studied in details by means of AIMD simulations and compared to the experimental results. The evolution of bond angle distributions, interatomic distances and coordination numbers are examined and lead to similar pressure-induced structural changes for any composition.Wed, 22 Jun 2016 11:36:57 GMTMagneto-optical trapping of iron atoms
http://hdl.handle.net/2268/198816
Title: Magneto-optical trapping of iron atoms
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<br/>Author, co-author: Crauwels, Justine; Huet, Nicolas; Krins, Stéphanie; Bastin, ThierryWed, 22 Jun 2016 09:18:58 GMT