3,479 research outputs found

    Austrian Partners in Joint Ventures With Companies from CMEA Countries: Problems Today

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    International research institutes involved in comparative global studies are not normally involved in the education of students or their respective studies. However, this study on joint ventures between Austrian enterprises and companies from CMEA countries was undertaken by students of the Vienna University of Economics and Business Administration with the assistance of IIASA scientists. This exceptional example proves that such cooperation can be most successful and mutually beneficial. Cooperation can be summarized in that IIASA would provide methodological guidance, data, literature and organize a series of lectures on East-West cooperation with special emphasis on joint ventures. These lectures were given by experts from CMEA countries and Austria; each lecture being followed by a discussion not only on joint ventures but also on economic reform in CMEA countries and national business practice. Simultaneously, hypotheses, questionnaires and plans for interviews were developed jointly. The main objective of the study was to look at the problems that Western partners meet in the process of negotiating and operating joint ventures with Eastern companies. The study consisted of two parts: first, theoretical -- elaboration of methodology, basic concepts and hypothesis; and second, empirical -- revealing specific problems of joint venture creation and operation from the Austrian partner's viewpoint. This sample of managers from 20 companies represents half of the Austrian partners involved in joint ventures at the end of 1988. Normally joint ventures begin their activities within one year from the date of registration and stabilize after two to three years. Austria ranked second among the countries establishing joint ventures; ranked by the number of joint ventures created and by the share of joint venture contracts with CMEA among all contracts of industrial cooperation of the country -- 33.3%. The findings in this Working Paper do not always meet the assumptions; but this is a sign that joint ventures have used opportunities in some areas and found ways to overcome difficulties. Other important and promising issues which resulted from the study are: (1) Recognition and mutual understanding of two different systems and business environments was observed and considered vital by both East and West; (2) Willingness to cooperate and achieve synergy effects by Austrian partners and their readiness to share their experience and enter into another joint venture; (3) The lack of some goods and raw materials in CMEA countries combined with longer delivery times and the monopolistic position of suppliers on the domestic market, etc., turned out to be the main problems. (4) It can be generally stated that joint ventures are a good means of managerial know-how transfer. However, difficulties in managing East-West joint ventures can be found in two main areas: new methods and techniques (EDP and telecommunication) and in the functional area of personnel management. Although the management of joint venturers is not a particular problem. (5) The importance of a new type of "cooperation" management emerged from the study. It can be stated that based on the subjective views of the businessmen interviewed, the results are not far removed from other national research studies. Obviously the specific features of the countries play an important role but do not drastically change the shape of the problems. Criticism of the study can also be made. Some of the hypothesis and elaborated assumptions are not based on real data and facts from CMEA countries. The short period of study did not permit an extensive research of literature on and from CMEA countries. In addition, the number of managers who did not answer some questions was high thereby offering different subjective interpretations. However, the approach and the structure of this research could, in the future, serve as a constantly repeating check-up on East-Austrian economic ventures and their development. This study was the first of its kind carried out at IIASA and in the field. Even considering that only 20 out of 40 companies were studied, the results can be regarded as a barometer of Austrian partnership in ventures with CMEA countries

    Semiclassical theory of cavity-assisted atom cooling

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    We present a systematic semiclassical model for the simulation of the dynamics of a single two-level atom strongly coupled to a driven high-finesse optical cavity. From the Fokker-Planck equation of the combined atom-field Wigner function we derive stochastic differential equations for the atomic motion and the cavity field. The corresponding noise sources exhibit strong correlations between the atomic momentum fluctuations and the noise in the phase quadrature of the cavity field. The model provides an effective tool to investigate localisation effects as well as cooling and trapping times. In addition, we can continuously study the transition from a few photon quantum field to the classical limit of a large coherent field amplitude.Comment: 10 pages, 8 figure

    Scaling properties of cavity-enhanced atom cooling

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    We extend an earlier semiclassical model to describe the dissipative motion of N atoms coupled to M modes inside a coherently driven high-finesse cavity. The description includes momentum diffusion via spontaneous emission and cavity decay. Simple analytical formulas for the steady-state temperature and the cooling time for a single atom are derived and show surprisingly good agreement with direct stochastic simulations of the semiclassical equations for N atoms with properly scaled parameters. A thorough comparison with standard free-space Doppler cooling is performed and yields a lower temperature and a cooling time enhancement by a factor of M times the square of the ratio of the atom-field coupling constant to the cavity decay rate. Finally it is shown that laser cooling with negligible spontaneous emission should indeed be possible, especially for relatively light particles in a strongly coupled field configuration.Comment: 7 pages, 5 figure

    Laboratory Model Shaking Table; An Investigation of Defects and Suggested Improvements

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    The laboratory model is considered in this thesis. Information gained from this investigation has not been trans­ferred to the larger industrial machines. Some of the factors noted concerning the efficiency of the laboratory shaking table are inherent in this small scale model only

    Disorder-enhanced phase coherence in trapped bosons on optical lattices

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    The consequences of disorder on interacting bosons trapped in optical lattices are investigated by quantum Monte Carlo simulations. At small to moderate strengths of potential disorder a unique effect is observed: if there is a Mott plateau at the center of the trap in the clean limit, phase coherence {\it increases} as a result of disorder. The localization effects due to correlation and disorder compete against each other, resulting in a partial delocalization of the particles in the Mott region, which in turn leads to increased phase coherence. In the absence of a Mott plateau, this effect is absent. A detailed analysis of the uniform system without a trap shows that the disordered states participate in a Bose glass phase.Comment: 4 pages, 4 figure

    Collective Sideband Cooling in an Optical Ring Cavity

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    We propose a cavity based laser cooling and trapping scheme, providing tight confinement and cooling to very low temperatures, without degradation at high particle densities. A bidirectionally pumped ring cavity builds up a resonantly enhanced optical standing wave which acts to confine polarizable particles in deep potential wells. The particle localization yields a coupling of the degenerate travelling wave modes via coherent photon redistribution. This induces a splitting of the cavity resonances with a high frequency component, that is tuned to the anti-Stokes Raman sideband of the particles oscillating in the potential wells, yielding cooling due to excess anti-Stokes scattering. Tight confinement in the optical lattice together with the prediction, that more than 50% of the trapped particles can be cooled into the motional ground state, promise high phase space densities.Comment: 4 pages, 1 figur

    On the suppression of the diffusion and the quantum nature of a cavity mode. Optical bistability; forces and friction in driven cavities

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    A new analytical method is presented here, offering a physical view of driven cavities where the external field cannot be neglected. We introduce a new dimensionless complex parameter, intrinsically linked to the cooperativity parameter of optical bistability, and analogous to the scaled Rabbi frequency for driven systems where the field is classical. Classes of steady states are iteratively constructed and expressions for the diffusion and friction coefficients at lowest order also derived. They have in most cases the same mathematical form as their free-space analog. The method offers a semiclassical explanation for two recent experiments of one atom trapping in a high Q cavity where the excited state is significantly saturated. Our results refute both claims of atom trapping by a quantized cavity mode, single or not. Finally, it is argued that the parameter newly constructed, as well as the groundwork of this method, are at least companions of the cooperativity parameter and its mother theory. In particular, we lay the stress on the apparently more fundamental role of our structure parameter.Comment: 24 pages, 7 figures. Submitted to J. Phys. B: At. Mol. Opt. Phy

    Ultracold atoms in optical lattices generated by quantized light fields

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    We study an ultracold gas of neutral atoms subject to the periodic optical potential generated by a high-QQ cavity mode. In the limit of very low temperatures, cavity field and atomic dynamics require a quantum description. Starting from a cavity QED single atom Hamiltonian we use different routes to derive approximative multiparticle Hamiltonians in Bose-Hubbard form with rescaled or even dynamical parameters. In the limit of large enough cavity damping the different models agree. Compared to free space optical lattices, quantum uncertainties of the potential and the possibility of atom-field entanglement lead to modified phase transition characteristics, the appearance of new phases or even quantum superpositions of different phases. Using a corresponding effective master equation, which can be numerically solved for few particles, we can study time evolution including dissipation. As an example we exhibit the microscopic processes behind the transition dynamics from a Mott insulator like state to a self-ordered superradiant state of the atoms, which appears as steady state for transverse atomic pumping.Comment: 17 pages, 10 figures, Published versio
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