Heterogeneous catalysis plays a significant role in the chemical industry and the global economy. Most heterogeneous catalysts in the chemical industry and laboratory consist of supported metal nanoparticles, clusters and isolated (single) atoms. Understanding structure sensitivity and identifying the active site or sites are crucially essential for designing efficient catalysts. To determine the active sites of a catalyst for a particular chemical reaction, in-situ/operando spectroscopy, such as diffuse reflectance infrared Fourier transform spectroscopy (DRIFTS) and X-ray absorption fine structure (XAFS) spectroscopy, is usually implemented as characterization tools. However, understanding the limitation of the characterization tools is crucial to eliminate misleading conclusions. Therefore, the main object of this work is not only to characterize the catalyst before and after the reaction but to investigate the reliability of the characterization tools as well as the stability of the metal clusters and single atoms during CO oxidation. There are four main findings that will be present in this work. First, a high-flux X-ray beam can induce structural change that leads to a reduction of the metal and agglomeration of metal clusters. This finding is very important since X-ray beam damage is uncommon for heterogeneous catalysis as for homogeneous catalysts and biological samples. In the study, the effect of high-flux X-ray on the Rh clusters and nanoparticles was highlighted along with providing mitigation strategies in order to reduce the damage caused by the high-flux X-ray beam. The second important finding is about the characterization of Rh clusters and nanoparticles during CO reduction treatment using DRIFTS. In this study, the integration of low-temperature CO oxidation kinetics as a characterization tool with DRIFTS, XAFS and scanning/transmission electron microscopy (STEM) was found to be necessary to improve the characterization of Rh single atoms. Implementing CO oxidation measurements at low temperatures can provide a rough estimation of the percentage of Rh single atoms. The third finding is related to the stability of Rh clusters upon exposure to CO, oxygen and CO oxidation at different temperatures. The study shows an unexpected dynamic structural change that the Rh cluster undergoes during exposure to oxygen even at room temperature in which the Rh clusters disperse to form Rh single atoms. This dispersion phenomenon was found to be size, gas environment and temperature dependent. For example, small clusters tend to disperse while large nanoparticles resist dispersion. additionally, increasing the temperature to ∼ 160 with CO and oxygen lead to an increase in the percentage of Rh single atoms. More importantly, the dispersed catalyst (Rh single atoms) exhibits higher CO oxidation activity than Rh nanoparticles by 350x. This finding can also be used for Rh single atoms synthesis for different oxide supports such as MgAl2O4, TiO2, and CeO2. Finally, the fourth finding is about investigating the CO oxidation kinetics and mechanism. The kinetics of Rh single atoms differ from Rh nanoparticles. Implementing in-situ spectroscopy helps to identify the resting state of the Rh complex during CO oxidation which is Rh(CO)2. By combining CO oxidation kinetics and in-situ spectroscopy, the plausible mechanism was suggested to be Eley-Rideal/Mars Van Krevelen mechanism. / Doctor of Philosophy / Heterogeneous catalysts are solid materials that scientists and chemical engineers use to convert undesirable raw reactants (liquid or gas) to other products (liquid or gas). One example of a heterogeneous catalyst is a catalytic converter used in most cars around the world. One goal of the catalytic converter is to convert CO (toxic gas) to CO2 (less toxic). The catalyst in a catalytic converter contains precious metals as nanoparticles such as Platinum (Pt), Palladium (Pd) and Rhodium (Rh) deposits on oxide supports (inert materials) such as Al2O3. These Pt, Pd and Rh nanoparticles help to accelerate the chemical reaction (e.g.CO oxidation) in which converting the toxic gas CO to CO2 at a relatively low temperature compared to if the reaction proceeds without those metal nanoparticles. In order to improve the performance of the catalyst, scientists and engineers implement characterization techniques to identify the active site based on the shape and size of the nanoparticles. One method to improve the catalyst performance is to decrease the particle size below 2 nm or even to reach isolated atoms. Unfortunately, synthesizing isolated (single) atoms supported on oxide support is very challenging. One main discovery presented in this work is that Rh single atoms can be synthesized using a simple but effective method. More importantly, Rh single atoms show higher performance than Rh nanoparticles by 350 times which helps to convert CO the toxic gas to CO2 at room temperature. This finding is important in which that the synthesis presented here can be used for different chemical reactions such as methane oxidation and methanol carbonylation.

Single-atom catalysts (SACs), as promising alternatives to Pt-based catalysts, suffer from the limited choice of center metals and low single-atom loading. Here, we report a pentacoordinated Zr-based SAC with nontrivial axial O ligands (denoted O−Zr−N−C) for oxygen reduction reaction (ORR). The O ligand downshifts the d-band center of Zr and confers Zr sites with stable local structure and proper adsorption capability for intermediates. Consequently, the ORR performance of O−Zr−N−C prominently surpasses that of commercial Pt/C, achieving a half-wave potential of 0.91 V vs. reversible hydrogen electrode and outstanding durability (92 % current retention after 130-hour operation). Moreover, the Zr site shows good resistance towards aggregation, enabling the synthesis of Zr-based SAC with high loading (9.1 wt%). With the high-loading catalyst, the zinc-air battery (ZAB) delivers a record-high power density of 324 mW cm−2 among those of SAC-based ZABs.

Many pathogenic bacteria can enter phagocytic cells and replicate in them, and these intracellular bacteria are difficult to treat because the recommended antibiotics do not transport into the cells efficiently. Examples include food-borne bacteria such as Salmonella and Listeria as well as more toxic bacteria such as Brucella and the Mycobacteria that lead to tuberculosis. Current treatments utilize aminoglycoside antibiotics that are polar and positively charged and such drugs do not enter the cells in sufficient concentrations to eradicate the intracellular infections. We have developed core-shell polymeric drug delivery vehicles containing gentamicin to potentially overcome this challenge. Pentablock and diblock copolymers comprised of amphiphilic nonionic polyether blocks and anionic poly(sodium acrylate) blocks have been complexed with the cationic aminoglycoside gentamicin. The electrostatic interaction between the anionic polyacrylates and the cationic aminoglycosides form the cores of the nanoplexes, while the amphiphilic nature of the polyethers stabilize their dispersion in physiological media. The amphiphilic nature of the polyethers in the outer shell aid in interaction of the nanoplexes with extra- and intra-cellular components and help to protect the electrostatic core from any physiological media. This thesis investigates the electrostatic cooperativity between the anionic polyacrylates and cationic aminoglycosides and evaluated the release rates of gentamicin as a function of pH. / Master of Science

The algebra of SU(2) is ubiquitous in physics, applicable both to the atomic spin states and the polarisation states of light. The method developed by Majorana and Schwinger to represent pure, symmetric spin-states of arbitrary value as a product of spin-1/2 states is a powerful tool that allows for a great conceptual and practical simplification. Foremost, it allows the representation of a qudit on the same geometry as a qubit, i.e., the Bloch sphere. An experimental implementation of the Majorana representation in the realm of quantum optics is presented. The technique allows the projection of arbitrary quantum states from a coherent state input. It is also shown that the method can be used to synthesise arbitrary interference patterns with unit visibility, and without resorting to quantum resources. In this context, it is argued that neither the shape nor the visibility of the interference pattern is a good measure of quantumness. It is only the measurement scheme that allows for the perceived quantum behaviour. The Majorana representation also proves useful in delineating uncertainty limits of states with a particular spin value. Issues with traditional uncertainty relations involving the SU(2) operators, such as trivial bounds for certain states and non-invariance, are thereby resolved with the presented pictorial solution. / <p>QC 20170428</p>

Fine-pitch ferroelectric domain gratings are extensively used for generation of light in the visible and near-infrared spectral regions through quasi-phase matched (QPM) frequency conversion. Sub-μm QPM devices enables demonstration of nonlinear optics with counterpropagating waves, a field of nonlinear optics which remains sparsely explored due to the difficulty of fabricatinghigh quality gratings. In recent years, bulk Rb-doped KTiOPO4 (RKTP) has emerged as a highly promising nonlinear materials for fabrication of fine-pitch QPM devices through periodic electric-field poling. RKTP possesses large optical nonlinearity and high resistance to optical damage, while demonstrating improved material homogeneity and lower ionic conductivity than its isomorphs, which are important features for poling. Although fine-pitch QPM gratings, as well as large aperture QPM devices, have been demonstrated, fabrication of sub-μm high quality QPM devices remains a challenge. The primary aim of this research was to develop a reliable method to fabricate high-quality sub-μm periodically poled RKTP crystals (PPRKTP) and exploit them in novel optical applications. For this purpose, a novel poling method was developed. It was based on periodic modulation of the coercive field through ion exchange, where K+ ions are exchanged with Rb+ in the crystal, to modulate the coercive field and the ionic conductivity. This enables periodic poling of higher quality and with shorter period than ever before. High quality PPRKTP with a period of 755 nm were fabricated and used to demonstrate the first cascaded mirrorless optical parametric oscillator (MOPO), as well as the first MOPO pumped by a Q-switched laser. PPRKTP samples for blue light generation were fabricated, and second harmonic generation (SHG) was investigated with a high power 946 nm fiber laser. Up to 2 W of blue power was demonstrated for bulk samples, where the output power was limited by absorption of the SHG, leading to thermal dephasing of the devices. Laser-written waveguides were fabricated in PPRKTP for the first time, and a record high SHG power of 76 mW was obtained. Finally, the high-temperature stability of ferroelectric domain gratings was investigated. This is of utmost importance when a PPRKTP crystal is used as a seed for crystal growth. It was found that for charged domains walls, the domain-wall motion was highly anisotropic with rapid movement in y-direction while only small movements were observed in the x-direction of the crystal. / Ickelinjära ferroelektriska kristaller med artificiella domängitter med perioder av några mikrometer används idag för generering av ljus i de synliga och nära-infraröda våglängdsområdena, genom kvasifasmatchad (QPM) frekvenskonvertering. Med sub-μm QPM domängitter kan man åstadkomma ickelinjära optiska effekter med motpropagerande parametriska ljusvågor. Detta är ett område av den ickelinjära optiken som fortfarande är tämligen outforskat på grund av svårigheten med att tillverka högkvalitativa domängitter.  Under de senaste åren har Rb-dopat KTiOPO4 (RKTP) blivit ett mycket lovande ickelinjärt material för tillverkning av QPM-gitter med mycket korta perioder genom periodisk elektrisk fält polning. RKTP kristallen har en hög optisk ickelinejäritet och den tål höga optiska intensiteter, samtidigt som materialet har bättre materialhomogenitet och lägre jonledningsförmåga än vad dess isomorfa kristaller har. De två senare egenskaperna har visat sig viktiga för att få en lyckad polning. Fastän QPM-gitter med kort periodicitet, liksom QPM-gitter med stor apertur, har demonstrerats, är tillverkningen av högkvalitativa QPM-kristaller med sub-µm perioder fortfarande en utmaning. Det primära syftet med denna avhandling var att utveckla en pålitlig metod för att tillverka högkvalitativa sub-μm periodiskt polade RKTP kristaller (PPRKTP) och utnyttja dem i nya optiska tillämpningar. I detta syfte utvecklades en ny polningsmetod. Den baseras på periodiskt jonutbyte, där K+ joner byts mot Rb+ i kristallen, vilket resulterar i en samtidig modulation av materialets koerciva fält och jonledningsförmåga. Detta möjliggör i sin tur periodisk polning av högre kvalitet och med kortare perioder än någonsin tidigare har uppnåtts. Högkvalitativa PPRKTP kristaller med en period på 755 nm tillverkades och användes för att demonstrera den första kaskaderade spegelfria optiska parametriska oscillatorn (MOPO), liksom den första MOPO processen pumpad av en Q-switchad laser. Vidare utvecklades PPRKTP-kristaller för generering av blått ljus via frekvensdubbling. Dessa utvärderades med hjälp av en högeffekts-fiberlaser vid 946 nm. Upp till 2 W av blått ljus erhölls för bulkkristallerna. Uteffekten begränsades av absorption av det blåa frekvensdubblade ljuset, vilket ledde till urfasning i QPM-gittret p.g.a. termiska effekter. Laserskrivna vågledare tillverkades sedan i PPRKTP för första gången, och en rekordhög effekt på 76 mW erhölls via frekvensdubbling. Slutligen undersöktes stabiliteten hos de periodiskt polade domängitterna vid höga temperaturer. Det är viktigt att domängittrena är stabila när PPRKTP kristallerna används som ympämne för kristalltillväxt. Det visade sig att instabila domänväggar flyttade sig mycket anisotropt, med en snabb rörelse i kristallens y-riktning och en långsam rörelse i kristallens x-riktning. / <p>QC 20170519</p>

This thesis presents experimental studies of three different chemical reaction steps relevant for heterogeneous catalysis: dissociation, desorption, and oxidation. CO on single-crystal metal surfaces was chosen as the model systems. X-ray absorption spectroscopy (XAS) and x-ray emission spectroscopy (XES) provide information about the electronic structure, and were performed on CO/Fe to measure both a non-dissociative, and a pre-dissociative state. The measurement on the pre-dissociative state showed a π →  π* excitation, which implies a partly broken internal π bond in the molecule. Ultrafast laser-induced reactions were used to examine the dynamic properties of desorption and oxidation. Here CO/Ru and CO/O/Ru were used as model systems. Desorption of CO from a Ru surface involve both hot electrons and phonons. In the case of CO oxidation from CO/O/Ru a pronounced wavelength dependence of the branching ratio between desorption and oxidation was observed. Excitation with 400 nm showed a factor of 3-4 higher selectivity towards oxidation than 800 nm. This was attributed to coupling to transiently excited, non-thermalized electrons. Finally, by performing optical pump/x-ray probe XAS and XES changes in the electronic structure during the reaction could be followed, both for desorption and oxidation. In the CO/Ru experiment, two different transient excitation paths were observed, one leading to a precursor state, and one where CO moves into a more highly coordinated site. Using selective excitation in XES, these were shown to coexist on the surface. In the oxidation experiment, probing the reacting species located near the transition state region in an associative catalytic surface reaction was demonstrated for the very first time.

At the MAX-IV lab in Lund, there is a current goal to build a new soft X-Ray laser. The beam will be generated from a free-electron laser (FEL), which is an instrument consisting of high-speed electrons. The electrons move through alternating magnetic fields, causing the beam to become monochromatic. After the FEL, the Xrays will enter a beamline consisting of different optical components, such as mirrors, gratings and slits. This project investigated the necessary parameter values of the components, in order for the new X-Ray laser to focus the beam enough. The project consisted of a theoretical part and a simulation part. The use of so-called Kirkpatrick-Baez mirrors enables the beam to be very focused. The best focus achieved was 7.23um*10.87um for ''Pink beamline'' and the intensity at the end was 71.5%, which meant that only 30% of the rays were lost. For the monochromatic beamline, a loss of intensity is inevitable. With a pair of KBmirrors, this beam was focused to be 6.95um*9.80um. The energy spread is ranging from 6.198 eV to 0.3442 eV. The analytical calculations for the spot size matched well with the simulations. The pink beamline which was built in Ray satisfied the criterias of a spot size and intensity loss. The monochromatic beamline did fullfil the criterias of spot size and narrowing the energy spread. A loss of intensity will for this beamline be inevitable. Studying the misalignment effect showed that the components were most sensitive for vertical misalignment. The most sensitive parameters were the curvature of the mirrors.

Direct volume rendering techniques for scalar fields make use of transfer functions to map optical properties to the field; the field can subsequently be visualized through the drawing of isosurfaces in the volume spanned by the field. The utility of this approach is limited in the case of nested or clustered structures with the same isovalue and further does not easily allow for quantitative measurements of the visualized data. This report explores the use of topological structures (contour trees and Morse-Smale complexes) as an augmentation of traditional direct volume rendering and describes a fully functional implementation in the visualization software Inviwo. The implementation is evaluated through analysis of valency charge density fields in cubic MgO2 and FeO2. It is demonstrated that both contour trees and Morse-Smale complexes provide information and segmentation of initial volume data that allows for selective transfer function application (based on the segmentation), on-demand information on critical points and an overview of the scalar field through a topological representation embedded in the visualized volume. Analysis of the provided charge density fields show that contour trees generate physically irrelevant artefacts and thus are ill-suited for analysing highly symmetric data. On the other hand, the Morse-Smale complex approach is used to extract information of the bond strength of O-O contacts in MgO2 and FeO2 consistent with previous findings, as well as information on electronic charge configuration consistent with previous findings on MgO2. In the case of FeO2, the electronic configuration results are not consistent. This is speculated to be due to a combination of factors, most notably the lack of periodic boundary conditions in the implementation and the more complicated structure of FeO2.   In light of the partially accurate data analysis, as well as the added functionality and utility provided to visualization software, this approach to topology-guided visualization is considered promising and worthy of further study and/or development.

Diese Arbeit beschäftigt sich mit der theoretischen Beschreibung eines Hybridsystems eines ultrakalten neutralen Atoms und eines einzelnen Ions. Diese Hybrid-Atom-Ion-Systeme verbinden die wichtigsten Vorteile von ultrakalten neutralen Atomen und Ionen. Neutrale Atome sind leicht skalierbar vor allem und können in großen Stückzahlen vorbereitet werden, wahrend gefangene Ionen über längere Zeiten gelagert werden können und leicht kontrollierbar sind. Einige der vorgeschlagenen Aussichten der hybriden Quantensysteme umfassen die sympathische Kühlung von eingefangenen Ionen, die ultrakalte Chemie, das Quantum Informationsverarbeitung, und Atom-Ionen-Quantensimulatoren. Diese Anwendungen erfordern eine äußerst präzise Steuerung und damit eine sehr genaue theoretische Modellierung. Eine neue Methode, die eine vollständige sechsdimensionale Behandlung von zwei Partikeln ermöglicht In räumlich getrennten dreidimensionalen Fangpotentialen wurde entwickelt. Indem man die raumliche Verschiebung zwischen den Einfangpotentialen erlaubt, ist es möglich, die gesteuerte Bewegung eines einzelnen Ions durch ein optisches Gitterpotential zu beschreiben, das mit neutralen Atomen gefüllt ist. Die Wechselwirkung zwischen dem neutralen Atom und dem geladenen Ion wird durch eine realistische Born-Oppenheimer Potentialkurve beschrieben. Eines der hier diskutierten Hybridsysteme ist 7Li2+ Isotop, das mit der neu entwickelten Methode untersucht wird, dabei wurden vermiedene Kreuzungen im Energiespektrum zwischen molekularen Zuständen und den Schwingungszuständen des Fallenpotentials als Funktion des Abstandes zwischen den beide Fallen beobachtet. Diese vermiedenen Kreuzungen bestatigen die bereits vorhergesagten falleninduzierten Resonanzen, die mithilfe der Quantendefekttheorie bestimmt wurden. Ebenfalls werden die erst kürzlich entdeckten inelastischen falleninduzierten Resonanzen in ultrakalten Atomen auch in den Atom-Ion Systemen beobachtet. / This thesis deals with the theoretical description of a hybrid system of an ultracold neutral atom and a single ion. These hybrid atom-ion systems combine the key advantages of ultracold neutral atoms and ions. In particular, neutral atoms are easily scalable and can be prepared in large numbers, while trapped ions can be stored for much longer times and are easy to control. Some of the proposed prospects of the hybrid quantum systems include sympathetic cooling of trapped ions, ultracold chemistry, quantum information processing, and atom-ion quantum simulators. These applications require extremely precise control and thus very accurate theoretical modeling. A new method that allows for a full 6-dimensional treatment of two particles in spatially separated 3-dimensional trapping potentials was developed. By allowing for the spatial displacement between the trapping potentials, it is possible to describe the controlled motion of a single ion through an optical-lattice potential filled with neutral atoms. The interaction between the neutral atom and the ion is modeled using realistic Born-Oppenheimer potential curves from ab initio quantum chemistry calculations. An application of the developed approach to the hybrid atom-ion system reveals avoided crossings between the molecular bound states and the unbound trap states as a function of the separation between the two traps. These avoided crossings correspond to trap-induced resonances. This finding confirms the trap-induced resonances predicted earlier based on quantum-defect-theory calculations. Also, the recently found inelastic confinement-induced resonances in ultracold neutral atoms are demonstrated to be present in atom-ion systems. These resonances arise due to the coupling between the center-of-mass and relative motions. The inelastic confinement-induced resonances could be used in coherent molecular ion formation and in the determination of atom-ion scattering properties like the scattering lengths.

Microfabricated solid-state surfaces, also called atom chip', have become a well-established technique to trap and manipulate atoms. This has simplified applications in atom interferometry, quantum information processing, and studies of many-body systems. Magnetic trapping potentials with arbitrary geommetries are generated with atom chip by miniaturized current-carrying conductors integrated on a solid substrate. Atoms can be trapped and cooled to microKelvin and even nanoKelvin temperatures in such microchip trap. However, cold atoms can be significantly perturbed by the chip surface, typically held at room temperature. The magnetic field fluctuations generated by thermal currents in the chip elements may induce spin flips of atoms and result in loss, heating and decoherence. In this thesis, we extend previous work on spin flip rates induced by magnetic noise and consider the more complex geometries that are typically encountered in atom chips: layered structures and metallic wires of finite cross-section. We also discuss a few aspects of atom chips traps built with superconducting structures that have been suggested as a means to suppress magnetic field fluctuations. The thesis describes calculations of spin flip rates based on magnetic Green functions that are computed analytically and numerically. For a chip with a top metallic layer, the magnetic noise depends essentially on the thickness of that layer, as long as the layers below have a much smaller conductivity. Based on this result, scaling laws for loss rates above a thin metallic layer are derived. A good agreement with experiments is obtained in the regime where the atom-surface distance is comparable to the skin depth of metal. Since in the experiments, metallic layers are always etched to separate wires carrying different currents, the impact of the finite lateral wire size on the magnetic noise has been taken into account. The local spectrum of the magnetic field near a metallic microstructure has been investigated numerically with the help of boundary integral equations. The magnetic noise significantly depends on polarizations above flat wires with finite lateral width, in stark contrast to an infinitely wide wire. Correlations between multiple wires are also taken into account. In the last part, superconducting atom chips are considered. Magnetic traps generated by superconducting wires in the Meissner state and the mixed state are studied analytically by a conformal mapping method and also numerically. The properties of the traps created by superconducting wires are investigated and compared to normal conducting wires: they behave qualitatively quite similar and open a route to further trap miniaturization, due to the advantage of low magnetic noise. We discuss critical currents and fields for several geometries. / Mikrotechnologische Oberflächen, sogenannte Atomchips, sind eine etablierte Methode zum Speichern und Manipulieren von Atomen geworden. Das hat Anwendungen in der Atom-Interferometrie, Quanteninformationsverarbeitung und Vielteilchensystemen vereinfacht. Magnetische Fallenpotentiale mit beliebigen Geometrien werden durch Atomchips mit miniaturisierten stromführenden Leiterbahnen auf einer Festkörperunterlage realisiert. Atome können bei Temperaturen im $mu$ K oder sogar nK-Bereich in einer solchen Falle gespeichert und gekühlt werden. Allerdings können kalte Atome signifikant durch die Chip-Oberfläche gestört werden, die sich typischerweise auf Raumtemperatur befindet. Die durch thermische Ströme im Chip erzeugten magnetischen Feldfluktuationen können Spin-Flips der Atome induzieren und Verlust, Erwärmung und Dekohärenz zur Folge haben. In dieser Dissertation erweitern wir frühere Arbeiten über durch magnetisches Rauschen induzierte Spin-Flip-Ratenund betrachten kompliziertere Geometrien, wie sie typischerweise auf einem Atom-Chip anzutreffen sind: Geschichtete Strukturen und metallische Leitungen mit endlichem Querschnitt. Wir diskutieren auch einige Aspekte von Aomchips aus Supraleitenden Strukturen die als Mittel zur Unterdrückung magnetischer Feldfluktuationen vorgeschlagen wurden. Die Arbeit beschreibt analytische und numerische Rechnungen von Spin-Flip Raten auf Grundlage magnetischer Greensfunktionen. Für einen Chip mit einem metallischen Top-Layer hängt das magnetische Rauschen hauptsächlich von der Dicke des Layers ab, solange die unteren Layer eine deutlich kleinere Leitfähigkeit haben. Auf Grundlage dieses Ergebnisses werden Skalengesetze für Verlustraten über einem dünnen metallischen Leiter hergeleitet. Eine gute Übereinstimmung mit Experimenten wird in dem Bereich erreicht, wo der Abstand zwischen Atom und Oberfläche in der Größenordnung der Eindringtiefe des Metalls ist. Da in Experimenten metallische Layer immer geätzt werden, um verschiedene stromleitende Bahnen vonenander zu trennen, wurde der Einfluß eines endlichen Querschnittsauf das magnetische Rauschen berücksichtigt. Das lokale Spektrum des magnetischen Feldes in der Nähe einer metallischen Mikrostruktur wurde mit Hilfe von Randintegralen numerisch untersucht. Das magnetische Rauschen hängt signifikant von der Polarisierung über flachen Leiterbahnen mit endlichem Querschnitt ab, im Unterschied zu einem unendlich breiten Leiter. Es wurden auch Korrelationen zwischen mehreren Leitern berücksichtigt. Im letzten Teil werden supraleitende Atomchips betrachtet. Magnetische Fallen, die von supraleitenden Bahnen im Meissner Zustand und im gemischten Zustand sind werden analytisch durch die Methode der konformen Abbildung und numerisch untersucht. Die Eigenschaften der durch supraleitende Bahnen erzeugten Fallen werden erforscht und mit normal leitenden verglichen: Sie verhalten sich qualitativ sehr ähnlich und öffnen einen Weg zur weiteren Miniaturisierung von Fallen, wegen dem Vorteil von geringem magnetischem Rauschen. Wir diskutieren kritische Ströme und Felder für einige Geometrien.