Universality and non-universality in the heteronuclear Efimov scenario with large mass imbalance

This thesis investigates universal and non-universal aspects of few-body physics in a mass-imbalanced mixture of ultracold bosonic $^{133}$Cs and fermionic $^6$Li atoms. For this purpose an experimental apparatus for the creation of quantum degenerate gases has been constructed. Using radio-frequency association of weakly-bound LiCs molecules and additional atom-loss spectroscopy we determine the two-body interaction properties between Li and Cs atoms at low collision energies. The analysis with a coupled-channels calculation yields precise singlet and triplet electronic ground state molecular potential curves, from which scattering lengths and positions of Fano-Feshbach resonances are extracted. These results represent almost a tenfold improvement over the previous determination, and are used to study few-body recombination processes and, for the first time, their dependence on the interaction strength between the heavy atoms close to two broad scattering resonances at various temperatures. Measurements of three-body loss rates reveal two series of three and two consecutive LiCs$_2$ Efimov resonances that demonstrate the universal scaling factor 4.9 between the first and second excited state resonances. The ground state resonance deviates from the discrete scaling law. By the use of hyperspherical formalism with either pairwise zero-range or Lennard-Jones model potentials we identify the van der Waals interaction between Cs atoms as a significant source of these modifications

Universality of weakly bound dimers and Efimov trimers close to Li-Cs Feshbach resonances

We study the interspecies scattering properties of ultracold Li-Cs mixtures in their two energetically lowest spin channels in the magnetic field range between 800 G and 1000 G. Close to two broad Feshbach resonances we create weakly bound LiCs dimers by radio-frequency association and measure the dependence of the binding energy on the external magnetic field strength. Based on the binding energies and complementary atom loss spectroscopy of three other Li-Cs s-wave Feshbach resonances we construct precise molecular singlet and triplet electronic ground state potentials using a coupled-channels calculation. We extract the Li-Cs interspecies scattering length as a function of the external field and obtain almost a ten-fold improvement in the precision of the values for the pole positions and widths of the s-wave Li-Cs Feshbach resonances as compared to our previous work [Pires \textit{et al.}, Phys. Rev. Lett. \textbf{112}, 250404 (2014)]. We discuss implications on the Efimov scenario and the universal geometric scaling for LiCsCs trimers

Universal three-body recombination and Efimov resonances in an ultracold Li-Cs mixture

We study Efimov resonances via three-body loss in an ultracold two-component gas of fermionic $^6$Li and bosonic $^{133}$Cs atoms close to a Feshbach resonance at 843~G, extending results reported previously [Pires \textit{et al.}, Phys. Rev. Lett. 112, 250404 (2014)] to temperatures around 120~nK. The experimental scheme for reaching lower temperatures is based upon compensating the gravity-induced spatial separation of the mass-imbalanced gases with bichromatic optical dipole traps. We observe the first and second excited Li-Cs-Cs Efimov resonance in the magnetic field dependence of the three-body event rate constant, in good agreement with the universal zero-range theory at finite temperature [Petrov and Werner, Phys. Rev. A 92, 022704 (2015)]. Deviations are found for the Efimov ground state, and the inelasticity parameter $\eta$ is found to be significantly larger than those for single-species systems

Informācijas un komunikācijas tehnoloģiju apgūšanas noteicošie faktori un izmantošanas problēmas Latvijas uzņēmumos

Anotācija. Promocijas darba mērķis ir apzināt, analizēt un izskaidrot faktorus, kas nosaka informācijas un komunikācijas tehnoloģiju (IKT) apgūšanu un izmantošanu Latvijas uzņēmumos, kā arī sagatavot priekšlikumus uzņēmumu konkurētspējas veicināšanai izmantojot IKT. Darba apjoms ir 172 lappuses. Darbā iekļauti arī 8 attēli, 45 tabulas un 1 pielikums. Darba 1. nodaļā aplūkota inovāciju ietekme uz uzņēmuma produktivitāti un darbību. 2. nodaļā apskatītas IKT ieviešanas un izplatības teorijas. 3. nodaļā izstrādāts modelis IKT apgūšanai un izmantošanai uzņēmumos, pamatoti faktori, kas to nosaka. Rezultātus var izmantot uzņēmumi, ekonomiskās attīstības plānošanā, kā arī mācību kursu sagatavošanai par IKT apguvi, lietošanu. Promocijas darba atziņas izklāstītas 8 publikācijās, par rezultātiem ziņots 7 zinātniskajos semināros, konferencēs. Atslēgvārdi: IKT, inovācijas, uzņēmums, modelēšana.Abstract. The work identifies, analyzes, and explains factors determining the adoption and use of ICT in Latvian companies, and makes recommendations on how to use these factors to promote competitiveness by using ICT. The work consists of 172 pages, including 8 figures, 45 tables, and 1 appendix. Chapter I discusses the impact of innovation activities on productivity and company performance. Chapter II studies theories of ICT adoption and diffusion. Chapter III presents a management model for ICT adoption at firm level in developing economy countries. The research findings can be used for company plans regarding ICT adoption and use, national development planning and preparing courses on ICT adoption and use. Thesis-related scientific publications include 8 publications. Research results have been presented at 7 conferences/seminars. Keywords: ICT, innovation, firm, modelling

Bibliometric Maps of BIM and BIM in Universities: A Comparative Analysis

Building Information Modeling (BIM) is increasingly important in the architecture and engineering fields, and especially in the field of sustainability through the study of energy. This study performs a bibliometric study analysis of BIM publications based on the Scopus database during the whole period from 2003 to 2018. The aim was to establish a comparison of bibliometric maps of the building information model and BIM in universities. The analyzed data included 4307 records produced by a total of 10,636 distinct authors from 314 institutions. Engineering and computer science were found to be the main scientific fields involved in BIM research. Architectural design are the central theme keywords, followed by information theory and construction industry. The final stage of the study focuses on the detection of clusters in which global research in this field is grouped. The main clusters found were those related to the BIM cycle, including construction management, documentation and analysis, architecture and design, construction/fabrication, and operation and maintenance (related to energy or sustainability). However, the clusters of the last phases such as demolition and renovation are not present, which indicates that this field suntil needs to be further developed and researched. With regard to the evolution of research, it has been observed how information technologies have been integrated over the entire spectrum of internet of things (IoT). A final key factor in the implementation of the BIM is its inclusion in the curriculum of technical careers related to areas of construction such as civil engineering or architecture

Analyzing Feshbach resonances -- A 6^6Li -133^{133}Cs case study

We provide a comprehensive comparison of a coupled channels calculation, the asymptotic bound state model (ABM), and the multichannel quantum defect theory (MQDT). Quantitative results for $^6$Li -$^{133}$Cs are presented and compared to previously measured $^6$Li -$^{133}$Cs Feshbach resonances (FRs) [M. Repp et al., Phys. Rev. A 87 010701(R) (2013)]. We demonstrate how the accuracy of the ABM can be stepwise improved by including magnetic dipole-dipole interactions and coupling to a non-dominant virtual state. We present a MQDT calculation, where magnetic dipole-dipole and second order spin-orbit interactions are included. A frame transformation formalism is introduced, which allows the assignment of measured FRs with only three parameters. All three models achieve a total rms error of < 1G on the observed FRs. We critically compare the different models in view of the accuracy for the description of FRs and the required input parameters for the calculations.Comment: 16 pages, 3 figures, 1 tabl

Quantum amplitude estimation with error mitigation for time-evolving probabilistic networks

We present a method to model a discretized time evolution of probabilistic networks on gate-based quantum computers. We consider networks of nodes, where each node can be in one of two states: good or failed. In each time step, probabilities are assigned for each node to fail (switch from good to failed) or to recover (switch from failed to good). Furthermore, probabilities are assigned for failing nodes to trigger the failure of other, good nodes. Our method can evaluate arbitrary network topologies for any number of time steps. We can therefore model events such as cascaded failure and avalanche effects which are inherent to financial networks, payment and supply chain networks, power grids, telecommunication networks and others. Using quantum amplitude estimation techniques, we are able to estimate the probability of any configuration for any set of nodes over time. This allows us, for example, to determine the probability of the first node to be in the good state after the last time step, without the necessity to track intermediate states. We present the results of a low-depth quantum amplitude estimation on a simulator with a realistic noise model. We also present the results for running this example on the AQT quantum computer system PINE. Finally, we introduce an error model that allows us to improve the results from the simulator and from the experiments on the PINE system