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Visar resultat 1 - 5 av 145 avhandlingar som matchar ovanstående sökkriterier.

1. 1. Laser cooling mechanisms and Brownian motors in optical lattices

   Författare :Peder Sjölund; Anders Kastberg; Svante Jonsell; Chris Westbrook; Umeå universitet; []
   Nyckelord :NATURVETENSKAP; NATURAL SCIENCES; Optical physics; Optisk fysik;

   Sammanfattning : Denna avhandling innefattar såväl experimentella som numeriska studier av laserkylda atomer i optiska kristallgitter. Bland annat har laserkylningsprocesser studerats, där atomers rörelser i optiska kristallgitter har uppvisat andra typer av bakomliggande mekanismer än de som tidigare förutsågs genom “Sisyfoskylningsmodellen”. LÄS MER

3. 2. Vortices and Persistent Currents in Rotating Bose Gases - a Diagonalization Approach

   Författare :Sara Bargi; Matematisk fysik; []
   Nyckelord :NATURVETENSKAP; NATURAL SCIENCES; Bose-Einstein condensation; vortices; superfluidity; Fysicumarkivet A:2010:Bargi;

   Sammanfattning : In this thesis, I explore the behavior of rotating ultra-cold Bose gases, by diagonalizing the Hamiltonian. This method has the advantage of being exact in the limit of weak interactions, and thus is a useful complement to the more commonly used Gross-Pitaevskii (GP) equation, which relies on a mean-field approximation. LÄS MER

4. 3. Gaps, Traps and Lattices - Correlations in Small Quantum Systems

   Författare :Magnus Borgh; Matematisk fysik; []
   Nyckelord :NATURVETENSKAP; NATURAL SCIENCES; magnetiska och optiska ; egenskaper elektriska; Cold atoms; Quantum dots; Optical lattices; classical mechanics; Mathematical and general theoretical physics; Exact diagonalization; Density Functional Theory; Vortices; relativity; quantum mechanics; termodynamik; statistisk fysik; relativitet; kvantmekanik; klassisk mekanik; Matematisk och allmän teoretisk fysik; thermodynamics; statistical physics; Condensed matter:electronic structure; gravitation; supraledare; magnetisk resonans; electrical; magnetic and optical properties; supraconductors; magnetic resonance; relaxation; spectroscopy; Kondenserade materiens egenskaper:elektronstruktur; spektroskopi; Fysicumarkivet A:2007:Borgh;

   Sammanfattning : This dissertation investigates properties of two-dimensional many-body systems. Studies are performed using the Spin-Density Functional Theory with the Local Spin-Density Approximation, and numerical exact diagonalization. LÄS MER

5. 4. Development of the Lund AMS Facility for the Detection of 59Ni – with Applications in the Nuclear Industry

   Författare :Per Persson; Kärnfysik; []
   Nyckelord :NATURVETENSKAP; NATURAL SCIENCES; AMS; Accelerator mass spectrometry; 59Ni; nuclear waste; chemical cobalt reduction; gas stripper; Nuclear engineering and technology; Kärnteknik; Fysicumarkivet A:2002:Persson;

   Sammanfattning : Accelerator mass spectrometry (AMS) is a highly sensitive method for counting atoms and it is used for detecting very low concentrations of both radionuclides and stable isotopes in small samples. The two major advantages of the AMS method are that the required amount of sample material is very small, but also that the efficiency is rather high, it takes less than an hour to analyse a sample. LÄS MER

7. 5. Molecular Structure and Packing of Platinum(II) Complexes with S-donor Ligands in the Solid State An X-ray Crystallographic Study

   Författare :Christian Hansson; Centrum för analys och syntes; []
   Nyckelord :NATURVETENSKAP; NATURAL SCIENCES; low temperature; high-pressure; structural class concept; hydrogen bonding; intermolecular interactions; crystallography; platinum coordination compounds; packing; phase transitions; Inorganic chemistry; Oorganisk kemi;

   Sammanfattning : How do molecules arrange themselves in a crystal? It is today not possible to definite predict the three-dimensional packing arrangement of molecules in the crystalline solid state. The aim of the work presented in this thesis has been to gain more knowledge of what principles that govern molecular packing. LÄS MER