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We investigate how consumer information affects price adjustment in the Austrian retail gasoline market. Our measure of consumer information is obtained from detailed census data on commuting behavior, as commuters can freely sample prices on their commuting route and are thus better informed about prices. A threshold error-correction model suggests that prices adjust more quickly if cost shocks exceed certain thresholds. Parametric and semi-parametric regressions show that a larger share of informed consumers increases both transmission speed and pass-through rate, but has no effect on the asymmetry of cost transmission.

Using a representative sample of European firms, we study whether financing constraints affect employers’ investments in employee training and physical capital differently. We measure financing constraints with an index that combines survey and balance sheet data. We instrument this index with the non-performing loans ratio of the bank that provided the last loan to the firms or with the average ratio of banks in the local area. We find that financing constraints have no effect on investment in training, but substantially reduce investment in physical capital.

Biomedical engineering online 20, 8 (2021). doi:10.1186/s12938-020-00841-9, Published by BioMed Central, London

There is an absence of broad-based and binding curricular requirements for structured competency-based post-graduate medical training in Germany, and thus no basis for comparing the competencies of physicians undergoing training in a medical specialty (Ärzte im Weiterbildung). In response, the German Society of Primary Care Pediatrics’ working group on post-graduate education (DGAAP) has identified realistic entrustable professional activities (EPAs) in primary care, defined their number, scope and content, selected competency domains, specified required knowledge and skills, and described appropriate assessment methods. These guidelines are referred to as PaedCompenda and can be accessed electronically by educators in pediatric medicine; the use and effectiveness of these guidelines are monitored by the German Association for Medical Education’s committee on post-graduate education (GMA). Teaching and training in pediatric medicine should take EPAs into consideration. To accomplish this, phases dedicated to primary care should be integrated into formal medical specialty training. Primary care pediatrics must enhance the sites where such training takes place into learning environments that prepare physicians trainees and turn the practicing specialists into mentoring educators., Für eine strukturierte kompetenzbasierte Weiterbildung fehlt eine flächendeckende, verbindliche curriculare Vorgabe und damit die Grundlage der Vergleichbarkeit der Kompetenzen von Ärztinnen in Weiterbildung (ÄiW). Die Arbeitsgruppe Weiterbildung der Deutschen Gesellschaft für Ambulante Allgemeine Pädiatrie (DGAAP) hat deshalb nach dem Konzept der Entrustable Professional Activities reale anvertraubare professionelle Tätigkeiten (APT) der Grundversorgung identifiziert, Anzahl und Umfang entschieden, Titel und Inhalte definiert, Kompetenzdomänen ausgewählt, erforderliches Wissen und notwendige Fähigkeiten spezifiziert und Prüfungsmethoden beschrieben. Diese Handreichung steht für pädiatrische Weiterbilder unter dem Namen PaedCompenda elektronisch zur Verfügung und wird in Anwendung und Wirksamkeit vom GMA-Ausschuss Weiterbildung begleitet. Die Praxis der Weiterbildung in der Pädiatrie sollte APTs berücksichtigen. Dazu ist die Einbindung ambulanter Abschnitte in der Facharztweiterbildung wünschenswert. Die primärversorgende Pädiatrie muss dazu ihre Lernorte zu vorbereiteten Lernumgebungen für Ärztinnen in Weiterbildung und ihre Praxisinhaber zu Lehrern weiterentwickeln., GMS Journal for Medical Education; 34(5):Doc67

We model the dynamics of attractively interacting ultracold bosonic atoms in a quasi-one-dimensional wave-guide with additional harmonic trapping. Initially, we prepare the system in its ground state and then shift the zero of the harmonic trap and switch on an additional narrow scattering potential near the center of the trap. After colliding with the barrier twice, we propose to measure the number of atoms opposite to the initial condition. Quantum-enhanced interferometry with quantum bright solitons allows us to predict detection of an offset of the scattering potential with considerably increased precision as compared to single-particle experiments. In a future experimental realization this might lead to measurement of weak forces caused, for example, by small horizontal gradients in the gravitational potential - with a resolution of several micrometers given essentially by the size of the solitons. Our numerical simulations are based on the rigorously proved effective potential approach developed in [Phys. Rev. Lett. 102, 010403 (2009) and Phys. Rev. Lett. 103, 210402 (2009)]. We choose our parameters such that the prerequisite of the proof (that the solitons cannot break apart, for energetic reasons) is always fulfilled, thus exploring a parameter regime inaccessible to the mean-field description via the Gross-Pitaevskii equation due to Schrodinger-cat states occurring in the many-particle quantum dynamics., 10 pages, 3 figures, minor revisions

In typical one-dimensional models the Mermin-Wagner theorem forbids long range order, thus preventing finite-temperature phase transitions. We find a finite-temperature phase transition for a homogeneous system of attractive bosons in one dimension. The low-temperature phase is characterized by a quantum bright soliton without long range order; the high-temperature phase is a free gas. Numerical calculations for finite particle numbers show a specific heat scaling as $N^2$, consistent with a vanishing transition region in the thermodynamic limit., 6 pages, 2 figures

Grand-canonical fluctuations of Bose-Einstein condensates of light are accessible to state-of-the-art experiments [J. Schmitt et al., Phys. Rev. Lett. 112, 030401 (2014).]. We phenomenologically describe these fluctuations by using the grand-canonical ensemble for a weakly interacting Bose gas at thermal equilibrium. For a two-dimensional harmonic trap, we use two models for which the canonical partition functions of the weakly interacting Bose gas are given by exact recurrence relations. We find that the grand-canonical condensate fluctuations for weakly interacting Bose gases vanish at zero temperature, thus behaving qualitatively similar to an ideal gas in the canonical ensemble (or micro-canonical ensemble) rather than the grand-canonical ensemble. For low but finite temperatures, the fluctuations remain considerably higher than for the canonical ensemble, as predicted by the ideal gas in the grand-canonical ensemble, thus clearly showing that we are not in a regime in which the ensembles are equivalent., Comment: 13 pages, 7 figures, revised manuscript

Two novel 2D and 3D coordination polymers of 9,10-triptycenedicarboxylic acid and zinc nitrate, which form under solvothermal reaction conditions, are described. As determined by single-crystal X-ray structure analysis, their frameworks are assembled from dinuclear zinc coordination units which are interlinked by triptycenedicarboxylato (TDC) struts. In the 2D-MOF reported here, the extended network of van der Waals interactions between triptycene units as well as coordinated solvent molecules is responsible for the dense assembly of layers with a 44 net topology into the final crystal structure. The framework of the 3D-MOF is composed from [Zn2(TDC)1.5]∞ layers with a 63 topology, the layers being interlinked by triptycenedicarboxylato pillars (bnn-net). This MOF possesses hexagonal channels which are filled with guest molecules.(© Wiley-VCH Verlag GmbH & Co. KGaA, 69451 Weinheim, Germany, 2008)

Using mobile technologies to remotely monitor patients has many potential benefits, not the least of which is the improvement in quality of life which patients experience when they are in their home environment rather than a hospital. This becomes particularly important when patients are suffering from a chronic disease such as diabetes, kidney failure, arteriosclerosis, or chronic obstructive pulmonary disease. The remote monitoring of medical parameters such as weight, blood pressure, blood sugar, and peak air flow can be augmented by technology that monitors the patients' compliance with drug regimes, to ensure that they enjoy maximal quality of life with minimal disruptive impact. This paper describes the work done by IBM Research to implement a state-of-the-art, open, pervasive health-care solution. One of the most important aspects of such a solution is how it is implemented in a real-life project; in this paper we describe the implementation of a system to monitor weight and blood pressure for pediatric nephrology cases at Germany's leading university hospital, within the context of both dialysis and post-transplantation recovery.

Multi-mode expansions in computational quantum dynamics promise convergence toward exact results upon increasing the number of modes. Convergence is difficult to ascertain in practice due to the unfavourable scaling of required resources for many-particle problems and therefore a simplified criterion based on a threshold value for the least occupied mode function is often used. Here we show how the separable quantum motion of the center of mass can be used to sensitively detect unconverged numerical multi-particle dynamics in harmonic potentials. Based on an experimentally relevant example of attractively interacting bosons in one dimension, we demonstrate that the simplified convergence criterion fails to assure qualitatively correct results. Furthermore, the numerical evidence for the creation of two-hump fragmented bright soliton-like states presented by Streltsov \emph{et al.} [PRL 100, 130401 (2008)] is shown to be inconsistent with exact results. Implications for our understanding of dynamical fragmentation in attractive boson systems are briefly discussed., 6 pages, 4 figures + 6 pages supplement

Brownian motion is ballistic on short time scales and diffusive on long time scales. Our theoretical investigations indicate that one can observe the exact opposite - an "anomaleous diffusion process" where initially diffusive motion becomes ballistic on longer time scales - in an ultracold atom system with a size comparable to macromolecules. This system is a quantum matter-wave bright soliton subject to decoherence via three-particle losses for which we investigate the center-of-mass motion. Our simulations show that such unusual center-of-mass dynamics should be observable on experimentally accessible time scales., Comment: 8 pages, 4 figures, minor revisions

We show that the spreading of the center-of-mass density of ultracold attractively interacting bosons can become superballistic in the presence of decoherence, via single-, two- and/or three-body losses. In the limit of weak decoherence, we analytically solve the numerical model introduced in [Phys. Rev. A 91, 063616 (2015)]. The analytical predictions allow us to identify experimentally accessible parameter regimes for which we predict superballistic spreading of the center-of-mass density. Ultracold attractive Bose gases form weakly bound molecules; quantum matter-wave bright solitons. Our computer-simulations combine ideas from classical field methods ("truncated Wigner") and piecewise deterministic stochastic processes. While the truncated Wigner approach to use an average over classical paths as a substitute for a quantum superposition is often an uncontrolled approximation, here it predicts the exact root-mean-square width when modeling an expanding Gaussian wave packet. In the superballistic regime, the leading-order of the spreading of the center-of-mass density can thus be modeled as a quantum superposition of classical Gaussian random walks in velocity space., Comment: 13 pages, 7 figures, minor changes

We report the observation of quantum reflection from a narrow, attractive, potential using bright solitary matter-waves formed from a 85Rb Bose-Einstein condensate. We create narrow potentials using a tightly focused, red-detuned laser beam, and observe reflection of up to 25% of the atoms, along with the trapping of atoms at the position of the beam. We show that the observed reflected fraction is much larger than theoretical predictions for a narrow Gaussian potential well; a more detailed model of bright soliton propagation, accounting for the generic presence of small subsidiary intensity maxima in the red-detuned beam, suggests that these small intensity maxima are the cause of this enhanced reflection., Comment: 5 pages, 4 figures

The standard calculations of the ground-state energy of a homogeneous Bose gas rely on approximations which are physically reasonable but difficult to control. Lieb and Yngvason [Phys. Rev. Lett. 80, 2504 (1998)] have proved rigorously that the commonly accepted leading order term of the ground state energy is correct in the zero-density-limit. Here, strong indications are given that also the next to leading term is correct. It is shown that the first terms obtained in a perturbative treatment provide contributions which are lost in the Bogoliubov approach., Comment: 6 pages, accepted for publication in Europhys. Lett. http://www.epletters.ch/

The non-equilibrium-steady state (NEST) for photons in a cavity is investigated theoretically. The NEST is caused by different parts of the cavity being at distinct temperatures or by temperature gradients. By using a rate equation based on the Lindblad equation, we derive an analytic expression for the steady-state distribution of the photon spectrum. We predict differences between the non-equilibrium steady state and a fit to the black-body spectrum calculated via Planck's law with an effective temperature. For two bodies of similar size at two temperatures which differ by a factor of two, the difference would be more than 10%. We also show that cavity resonances have a particularly large influence on the resulting non-equilibrium steady state of the photons. The investigation of thermal spectra in the presence of more than one temperature can be important for high-precision atomic clocks., 7 pages, 4 figures

In the past few decades spatial econometric models have become a standard tool in empirical research. Nevertheless applications in binary-choice models remain scarce. This paper makes use of Bayesian Spatial Probit Models to model and estimate spatial interactions in location decisions. For this purpose, we focus on the Austrian retail gasoline market, which is going through a process of remarkable structural changes. A short analysis shows that, during the last decade 10.9% of the stations had left the market and a percentage of 29.6% had either left the market or had changed the brand. This paper aims at investigating this process. A special characteristic of this market is the local competition structure which is characterized by spatial dependencies along local competitors. To capture these spatial dependencies and since the dependent variable is binary in nature (an exit had taken place or not), we apply a Bayesian spatial probit model using MCMC estimation on station level data for the whole Austrian retail gasoline market. Our results suggest, that the decision to leave the market, does not only depend on own characteristics, but also on competitors. In particular, we find the exit decisions to exhibit a negative spatial correlation. Moreover, our model allows to quantify spatial spillover effects of this market.

The generation of mesoscopic Bell states via collisions of distinguishable bright solitons has been suggested in Phys. Rev. Lett. 111, 100406 (2013). Here, we extend our former proposal to two hyperfine states of 85Rb instead of two different atomic species, thus simplifying possible experimental realisations. A calculation of the $s$-wave scattering lengths for the hyperfine states $(f,m_f)=(2,+2)$ and $(3,+2)$ identifies parameter regimes suitable for the creation of Bell states with an advantageously broad Feshbach resonance. We show the generation of Bell states using the truncated Wigner method for the soliton's centre of mass and demonstrate the validity of this approach by a comparison to a mathematically rigorous effective potential treatment of the quantum many-particle problem., Comment: 6 pages, 3 figures

We study bright solitons in the Gross-Pitaevskii equation as they are split and recombined in a low energy system. We present new analytic results determining the general region in which a soliton may not be split on a potential barrier, and confirm these results numerically. Furthermore, we analyse the energetic regimes where quantum fluctuations in the initial center of mass position and momentum become influential on the outcome of soliton splitting and recombination events. We then use the results of this analysis to determine a parameter regime where soliton interferometry is practicable., Comment: 15 pages, 11 figures

At low temperatures the organic salt adamantan-1-ammonium 4-fluorobenzoate, C10H18N+·C7H4FO2−, possesses an incommensurately modulated crystal structure. The effect of the modulation on the atomic arrangement and intermolecular interactions is studied by analysing single-crystal X-ray diffraction data within the (3 + 1)-dimensional superspace approach and superspace groupP21/n(α0γ)00. The modulation strongly affects the position of the atoms as well as their atomic displacement parameters. Nevertheless, the molecular cations and anions are built by rigid moieties, which vary their orientation with respect to each other as a function of the phase of the modulationt. Cations and anions are connected into slabs by dense N—H...O and C—H...F hydrogen-bonded networks, which are characterized by being rather rigid and which show only a little variation as a function of the phase of the modulationt.

The present paper provides first empirical evidence on the relationship between market size and the number of firms for a transition economy. We estimate size thresholds required to support different numbers of firms for seven retail and professional service industries in a large number of distinct geographic markets in Slovakia. The empirical analysis is carried out for three time periods (1995, 2001 and 2010) characterizing different stages of the transition process. Our results suggest that the relationship between market size and the number of firm has changed substantially over time. While entry threshold ratios tend to be larger than one and decline with the number of firms in most professions in 1995, the estimation results obtained for 2010 suggest entry threshold ratios much closer to one. This finding is consistent with observations suggesting a significant decline in entry barriers as well as an intensification of competition over time.

We investigate finite number effects in collisions between two states of an initially well defined number of identical bosons with attractive contact interactions, oscillating in the presence of harmonic confinement in one dimension. We investigate two $N/2$ atom bound states, which are initially displaced (symmetrically) from the trap center, and then left to freely evolve. For sufficiently attractive interactions, these bound states are like those found through use of the Bethe Ansatz (quantum solitons). However, unlike the free case, the integrability is lost due to confinement, and collisions can cause mixing into different bound state configurations. We study the system numerically for the simplest case of $N=4$, via an exact diagonalization of the Hamiltonian within a finite basis, investigating left/right number uncertainty as our primary measure of entanglement. We find that for certain interaction strengths, a phase matching condition leads to resonant transfer to different bound state configurations with highly non-Poissonian relative number statistics., Comment: 10 pages, 5 figures

a,w-Alkanedithiols show an alternation in their m.ps. with even members exhibiting systematically higher m.ps. than odd members. Single crystals of the 1st nine members of a,w-alkanedithiols (HS-(CH2)n-SH, n = 2-10) were grown in situ using a miniature zone melting procedure, and their x-ray crystal structure analyses were performed. The structural similarities and differences between even and odd members were analyzed based on the packing arrangements of hydrocarbon chains and SH functionalities. Whereas the hydrocarbon chains maintain an intergrooving pattern, the SH groups assoc. in an antiparallel fashion in both the members. The SH groups do not form H bonds. In the even members the mols. are offset along their length, whereas such an offset is not obsd. in the odd members. The densities of even members are systematically higher than those of odd members and show an alternating trend. Using a simple geometrical model, describing even and odd members as modified parallelograms and trapezoids, resp., the d. features of the packing patterns in both the members are illustrated. The m.p. alternation in dithiols is attributed to the geometry allowed or forbidden mol. offset toward a higher packing d.

γ-Hydroquinone (1) and its tetrafluoro, tetrachloro and tetrabromo derivatives (2), (3) and (4) adopt crystal structures that have an almost invariant system of O—H...O hydrogen bonds. However, within this O—H...O framework, the four structures display variations that are characteristic of the C—H, C—F, C—Cl and C—Br groups. In the parent compound (1) aromatic rings are packed with a herringbone geometry, whilst in the halogenated derivatives (3) and (4), polarization-type halogen...halogen contacts are optimized. The fluoro derivative (2) is exceptional in that neither of the above possibilities is adopted, even though the O—H...O scaffolding does not per se prohibit either of them geometrically.

In the crystal structure of the title compd., C25H20O.C8H15OP, the components are linked through O-H...O and C-H...O H bonds. The Ph rings of OPPh3 are close packed, while those of 4-(triphenylmethyl)phenol are involved in sextuple embrace type of packing. Crystallog. data are given.

The principles of crystal engineering have been used to design a family of structures with potential as octupolar nonlinear optical (NLO) materials. The major aim in such an exercise, a carry-over of molecular symmetry into the crystal, is possible with a retrosynthetic approach. An appropriate choice of precursor trigonal molecules leads from the concept of the dimeric Piedfort unit. The crystal structures and NLO properties of a series of 2,4,6-triaryloxy-1,3,5-triazines, 1−6, are reported. These compounds consistently form quasi-trigonal or trigonal networks that are two-dimensionally noncentrosymmetric. Substitutional variations on the phenyl moieties that were expected to maintain or to perturb this trigonal network have been explored. Molecular nonlinearities have been measured by Harmonic Light Scattering (HLS) experiments. Among the compounds studied, 2,4,6-triphenoxy-1,3,5-triazine, 1 adopts a noncentrosymmetric crystal structure with a measurable SHG powder signal. All these crystal structures a...

We investigate finite number effects in collisions between two states of an initially well known number of identical bosons with contact interactions, oscillating in the presence of harmonic confinement in one dimension. We investigate two N/2 (interacting) ground states, which are initially displaced from the trap center, and the effects of varying interaction strength. The numerics focus on the simplest case of N=4. In the non-interacting case, such a system would display periodic oscillation with a half harmonic oscillator period (due to the left-right symmetry). With the addition contact interactions between the bosons, collisions generate entanglement between each of the states and distribute energy into other modes of the oscillator. We study the system numerically via an exact diagonalization of the Hamiltonian with a finite basis, investigating left/right number uncertainty as our primary measure of entanglement. Additionally we study the time-evolution and equilibration of the single-body von Neumann entropy for both the attractive and repulsive cases. We identify parameter regimes for which attractive interactions create qualitatively different behavior to repulsive interactions, due to the presence of bound states (quantum solitons) and explain the processes behind this., 17 pages, 8 figures

The present paper provides first empirical evidence on the effects of entry on market conduct for a transition economy. We estimate size thresholds required to support different numbers of firms for seven retail and professional service industries in a large number of distinct geographic markets in Slovakia. Our results suggest a differential impact of entry on market conduct: while market conduct is unaffected by entry in the north-western parts of Slovakia, competition tends to kick in slowly in most professions in the south-east. This latter region suffers from infrastructure bottlenecks and competitors require a larger increase in the number of customers to come in.

For the dynamics of Bose-Einstein condensates (BECs), differences between mean-field (Gross-Pitaevskii) physics and $N$-particle quantum physics often disappear if the BEC becomes larger and larger. In particular, the timescale for which both dynamics agree should thus become larger if the particle number increases. For BECs in a double-well potential, we find both examples for which this is the case and examples for which differences remain even for huge BECs on experimentally realistic short timescales. By using a combination of numerical and analytical methods, we show that the differences remain visible on the level of expectation values even beyond the largest possible numbers realized experimentally for BECs with ultracold atoms., Comment: 10 pages, 4 png figures

We investigate numerically the collisions of two distinguishable quantum matter-wave bright solitons in a one-dimensional harmonic trap. We show that such collisions can be used to generate mesoscopic Bell states which can reliably be distinguished from statistical mixtures. Calculation of the relevant s-wave scattering lengths predicts that such states could potentially be realized in quantum-degenerate mixtures of 85Rb and 133Cs. In addition to fully quantum simulations for two distinguishable two-particle solitons, we use a mean-field description supplemented by a stochastic treatment of quantum fluctuations in the soliton's center of mass: We demonstrate the validity of this approach by comparison to a mathematically rigorous effective potential treatment of the quantum many-particle problem., Comment: 7 pages, 5 figures

Background: Amantadine constitutes an interesting, diamond crystal lattice-shaped, antivirally active amine with an inhibitory effect on influenza A viruses causing common ‘flu’ in humans. Unfortunately, amantadine forfeited most of its therapeutic potential because of resistance development in recent influenza A virus isolates. The antiviral efficacy of amantadine congeners can be chemically modified, resulting in re-constitution, improvement and/or extension of antiviral activities mediated by amino-adamantyls. Methods: Newly synthesized compounds were evaluated towards HIV type-1 (HIV-1) replication in primary human lymphocytes. One N-phenacyl amantadine derivative was investigated for inhibiting the in vitro replication of respiratory viruses (influenza A viruses, influenza B virus, human parainfluenza virus type 3 and severe acute respiratory syndrome coronavirus). Results: Two ketone-stabilized 1-adamantyl singlet nitrenes were discovered serendipitously. To our best knowledge these are the first persistently stable nitrenes to be reported. Their structure was proved by determining the X-ray single crystal structure of one hydrolytic elaboration product. This salt adduct revealed an incommensurately modulated crystal structure, which was solved by extensive computational refinement. We could show that ketone-stabilized 1-adamantyl singlet nitrenes are versatile synthons for the synthesis of antiviral drug candidates. An amantadine–folate conjugate was inhibitory on HIV-1 replication in primary human lymphocytes, and one N-phenacyl amantadine derivative was inhibitory towards low pathogenic avian influenza A virus (H5N1) replication in vitro. Conclusions: These results indicate that the aromatic-aliphatic ketone-stabilized 1-adamantyl singlet nitrenes, beyond being of fundamental interest in organic chemistry, represent versatile synthons for the synthesis of new amantadine-related potentially antiviral drugs.

We consider a one-dimensional matter-wave bright soliton, corresponding to the ground bound state of N particles of mass m having a binary attractive delta potential interaction on the open line. For a full N-body quantum treatment, we derive several results for the scattering of this quantum soliton on a short-range, bounded from below, external potential, restricting to the low energy, elastic regime where the centre-of-mass kinetic energy of the incoming soliton is lower than the internal energy gap of the soliton, that is the minimal energy required to extract particles from the soliton., 16 pages, 1 figure

For a periodically shaken optical lattice, effective time-reversal is investigated numerically. For interacting ultra-cold atoms, the scheme of [J. Phys. B 45, 021002 (2012)] involves a quasi-instantaneous change of both the shaking-amplitude and the sign of the interaction. As the wave function returns to its initial state with high probability, time-reversal is ideal to distinguish pure quantum dynamics from the dynamics described by statistical mixtures., Preprint-version, 7 pages, 4 figures

This paper investigates bright quantum-matter-wave solitons beyond the Gross-Pitaevskii equation (GPE). As proposals for interferometry and creating nonlocal quantum superpositions have been formed, it has become necessary to investigate effects not present in mean-field models. We investigate the effect of harmonic confinement on the internal degrees of freedom, as the ratio of zero-point harmonic oscillator length to classical soliton length, for different numbers of atoms. We derive a first-order energy correction for the addition of a harmonic potential to the many-body wave function and use this to create a variational technique based on energy minimization of this wave function for an arbitrary number of atoms, and include numerics based on diagonalization of the Hamiltonian in a basis of harmonic oscillator Fock states. Finally we compare agreement between a Hartree product ground state and the Bethe ansatz solution with a Gaussian envelope localizing the center of mass and show a region of good agreement., 20 pages, 5 figures, minor changes to text, references updated. Fixed date

For Bose-Einstein condensates in double wells, N-particle Rabi-like oscillations often seem to be damped. Far from being a decoherence effect, the apparent damping can indicate the emergence of quantum superpositions in the many-particle quantum dynamics. However, in an experiment it would be difficult to distinguish the apparent damping from decoherence effects. The present paper suggests using controlled periodic shaking to quasi-instantaneously switch the sign of an effective Hamiltonian, thus implementing an `echo' technique which distinguishes quantum superpositions from statistical mixtures. The scheme for the effective time-reversal is tested by numerically solving the time-dependent N-particle Schrodinger equation., Comment: Preprint-version, 5 pages, 5 png-figures

We investigate scattering bright solitons off a potential using both analytical and numerical methods. Our paper focuses on low kinetic energies for which differences between the mean-field description via the Gross-Pitaevskii equation (GPE) and the quantum behavior are particularly large. On the N-particle quantum level, adding an additional harmonic confinement leads to a simple signature to distinguish quantum superpositions from statistical mixtures. While the non-linear character of the GPE does not allow quantum superpositions, the splitting of GPE-solitons takes place only partially. When the potential strength is increased, the fraction of the soliton which is transmitted or reflected jumps non-continuously. We explain these jumps via energy-conservation and interpret them as indications for quantum superpositions on the N-particle level. On the GPE-level, we also investigate the transition from this stepwise behavior to the continuous case., Comment: 12 pages, 6 figures, minor changes

The scattering of bright quantum solitons at barrier potentials in one-dimensional geometries is investigated. Such protocols have been predicted to lead to the creation of nonlocal quantum superpositions. The centre-of-mass motion of these bright matter-wave solitons generated from attractive Bose-Einstein condensates can be analysed with the effective potential approach. An application to the case of two particles being scattered at a delta potential allows analytical calculations not possible for higher particle numbers as well as a comparison with numerical results. Both for the dimer and a soliton with particle numbers on the order of N = 100, we investigate the signatures of the coherent superposition states in an interferometric setup and argue that experimentally an interference pattern would be particularly well observable in the centre-of-mass density. Quantum superposition states of ultra-cold atoms are interesting as input states for matter-wave interferometry as they could improve signal-to-noise ratios., Comment: 10 pagers, 5 figures, references: error corrected

Fractional photon-assisted tunnelling is investigated both numerically and analytically in a double-well lattice. While integer photon-assisted tunnelling is a single-particle effect, fractional photon-assisted tunnelling is an interaction-induced many-body effect. Double-well lattices with few particles in each double well are ideal to study this effect far from the mean-field effects. It is predicted that the 1/4-resonance is observable in such systems. Fractional photon-assisted tunnelling provides a physically relevant model for which N-th order time-dependent perturbation theory can be large although all previous orders are small., Preprint-version; 9 pages, 9 png-figures

Fractional photon-assisted tunneling is investigated both analytically and numerically for few interacting ultra-cold atoms in the double-wells of an optical superlattice. This can be realized experimentally by adding periodic shaking to an existing experimental setup [Phys. Rev. Lett. 101, 090404 (2008)]. Photon-assisted tunneling is visible in the particle transfer between the wells of the individual double wells. In order to understand the physics of the photon-assisted tunneling, an effective model based on the rotating wave approximation is introduced. The validity of this effective approach is tested for wide parameter ranges which are accessible to experiments in double-well lattices. The effective model goes well beyond previous perturbation theory approaches and is useful to investigate in particular the fractional photon-assisted tunneling resonances. Analytic results on the level of the experimentally realizable two-particle quantum dynamics show very good agreement with the numerical solution of the time-dependent Schr\"odinger equation. Far from being a small effect, both the one-half-photon and the one-third-photon resonance are shown to have large effects on the particle transfer., Comment: 9 pages, 11 png-figures

In der heutigen Zeit sind Medien aller Art im alltäglichen Leben anzutreffen. Ob früh am Morgen die frisch gedruckte Zeitung, das Radio in der Küche, der Lieblingsfilm im Fernsehen oder das Internet via Mobiltelefon. Viele Menschen können sich heutzutage ein Leben ohne Mobiltelefon oder Fernsehgerät nicht mehr vorstellen. Die Industrie hat dies erkannt und bringt fast täglich neue Weiterentwicklungen auf den Markt. Smartphones, die beinahe so viel können wie ein Laptop oder Fernseher, die den Zuschauer via 3D-Technologie in das Geschehen eintauchen lassen, entwickeln sich zu Standardprodukten. Bei der heutigen Geschwindigkeit der Neuentwicklungen und den immer kürzer werdenden Produktlebenszyklen ist es besonders wichtig, den Endverbraucher vom Mehrwert zu überzeugen. In diesem Zusammenhang ist es notwendig herauszukristallisieren, worauf der Endkunde Wert legt und welche Informationsschwächen er hat. Hierzu haben acht Studierende der TH Wildau aus dem Fachbereich Betriebswirtschaft/Wirtschaftsinformatik eine empirische Studie entwickelt. In your everyday life, media of all kinds are found. Whether early in the morning, freshly printed newspaper, the radio in the kitchen, favorite movies on TV or the Internet via mobile phone. Many people can not imagine a life without mobile phone or TV. The industry has recognized that and almost every day they have new developments for the market. Smartphones have nearly as much as functions as a laptop or a television and are able to bring the viewers into actions via 3D technology as a standard. Because of the speed of new developments and the shortening product life cycle it is especially important to convince the consumer«s added value. In this case it is important to have a look what is significant for the end consumer and what lack of information does the consumer have. Concerning these problems, eight students of the University of Applied Science Wildau from the Department of Business Administration and Business Informatics designed an empirical study.