The doctoral dissertations of the former Helsinki University of Technology (TKK) and Aalto University Schools of Technology (CHEM, ELEC, ENG, SCI) published in electronic format are available in the electronic publications archive of Aalto University - Aaltodoc.
Aalto

Atom Traps on an Evanescent-Wave Mirror

Andriy Shevchenko

Dissertation for the degree of Doctor of Science in Technology to be presented with due permission of the Department of Engineering Physics and Mathematics for public examination and debate in Auditorium F1 at Helsinki University of Technology (Espoo, Finland) on the 8th of October, 2004, at 12 o'clock noon.

Overview in PDF format (ISBN 951-22-7290-3)   [1777 KB]
Dissertation is also available in print (ISBN 951-22-7289-X)

Abstract

During the past two decades the dramatic developments in cooling and trapping of gaseous atomic samples has produced a variety of techniques to manipulate the external and internal atomic states with electromagnetic fields. The research efforts so far have mainly focused on studying the fundamental aspects of modern quantum physics, although numerous practical applications, e.g., in integrated matter-wave optics and quantum information processing, are expected to soon be added to the already established atom-optics products, such as atomic clocks and acceleration sensors. One of the most promising foundations for the practical applications of Bose-Einstein condensates (BECs) and coherent matter waves is the technology based on the creation of microscopic atom traps on the surface of a solid substrate. This trapping technique has recently been used to successfully control the motion of microscopic atomic samples and to significantly simplify the creation of BEC.

The main research topic of this thesis is the development and design of surface-mounted atom traps on transparent dielectric substrates. Such traps could provide an extra flexibility and stability for the experiments, since they would allow unimpeded control of atoms with laser light and provide reduction of magnetic-field fluctuations associated with the thermal motion of free electrons in the substrate material. The thesis describes several novel approaches to the creation of such surface traps by superimposing repulsive evanescent optical waves with strongly localized magnetic or electric fields. These fields can be produced by either conductive or permanently magnetized, optically transparent patterns imprinted in a thin layer on a transparent dielectric substrate. The evanescent wave can also be used to cool the atoms in a gravitational field before loading them into the microtrap. The lateral confinement of the atoms on the evanescent wave can be realized with a thin-walled hollow laser beam, the creation of which is demonstrated in the thesis. The thesis also describes certain general aspects concerning evanescent-wave cooling. In particular, the influence that multiple reabsorption of resonance-frequency photons in a cloud of evanescent-wave cooled atoms has on the cooling efficiency is investigated. Also, a theoretical model based on classical statistical mechanics and thermodynamics is introduced to show how a microtrap on an evanescent-wave mirror can be used to decrease the temperature, increase the phase-space density, and provide temperature conserving spin-polarization of the atoms.

This thesis consists of an overview and of the following 5 publications:

  1. Shevchenko A., Buchter S. C., Tabiryan N. V. and Kaivola M., 2004. Creation of a hollow laser beam using self-phase modulation in a nematic liquid crystal. Optics Communications 232, pages 77-82. © 2004 Elsevier Science. By permission.
  2. Shevchenko A., Kaivola M. and Javanainen J., 2003. Heating and phase-space decompression of evanescent-wave cooled atoms by multiple photon reabsorption. Optics Express 11, number 16, pages 1827-1834. © 2003 Optical Society of America (OSA). By permission.
  3. Shevchenko A., Lindvall T., Tittonen I. and Kaivola M., 2004. Microscopic electro-optical atom trap on an evanescent-wave mirror. The European Physical Journal D 28, number 2, pages 273-276.
  4. Shevchenko A., Jaakkola A., Lindvall T., Tittonen I. and Kaivola M., 2004. Method for obtaining high phase space density in a surface-mounted atom trap. Applied Physics B: Lasers and Optics 79, number 3, pages 367-370.
  5. Shevchenko A., Kaivola M. and Javanainen J., 2004. Thermodynamics of a multicomponent-atom sample in a tightly compressed atom trap. Physical Review A 70, 011403 (R).

Errata of publication 5

Keywords: laser cooled atoms, evanescent-wave cooling, gravito-optical surface trap, microtraps

This publication is copyrighted. You may download, display and print it for Your own personal use. Commercial use is prohibited.

© 2004 Helsinki University of Technology

Last update 2011-05-26