A buffer-gas cooled Bose-Einstein condensate
by Doret, Stephen Charles, Ph.D., HARVARD UNIVERSITY, 2010, 223 pages; 3395422

Abstract:

We report the creation of a Bose-Einstein condensate using buffer-gas cooling, the first realization of BEC using a method which relies neither on laser cooling nor unique atom-surface properties. Metastable helium ( 4He*) is buffer-gas cooled and magnetically trapped using an optimized buffer-gas trapping apparatus, followed by evaporative cooling to quantum degeneracy. Evaporative cooling proceeds in two stages, each traversing approximately five orders of magnitude in phase space density. An initial stage of evaporation uses a surface to adsorb atoms, while a later stage uses radio-frequency induced spin-flips to evaporate atoms. Trapped atoms are detected using absorption and phase-contrast imaging both in-situ and in time-of-flight expansion. 1011 atoms are initially trapped, leading to Bose-Einstein condensation at a critical temperature of 5 μK and threshold atom number of 1.1 x 106. The method developed here is applicable to a wide array of paramagnetic atoms as well as molecules, many of which are impractical to laser cool and all of which are impossible to surface cool.

 
AdviserJohn Morrissey Doyle
SchoolHARVARD UNIVERSITY
SourceDAI/B 71-02, p. , Mar 2010
Source TypeDissertation
SubjectsLow temperature physics; Condensed matter physics; Atomic physics
Publication Number3395422
Adobe PDF Access the complete dissertation:
 

» Find an electronic copy at your library.
  Use the link below to access a full citation record of this graduate work:
  http://gateway.proquest.com/openurl%3furl_ver=Z39.88-2004%26res_dat=xri:pqdiss%26rft_val_fmt=info:ofi/fmt:kev:mtx:dissertation%26rft_dat=xri:pqdiss:3395422
  If your library subscribes to the ProQuest Dissertations & Theses (PQDT) database, you may be entitled to a free electronic version of this graduate work. If not, you will have the option to purchase one, and access a 24 page preview for free (if available).

About ProQuest Dissertations & Theses
With over 2.3 million records, the ProQuest Dissertations & Theses (PQDT) database is the most comprehensive collection of dissertations and theses in the world. It is the database of record for graduate research.

The database includes citations of graduate works ranging from the first U.S. dissertation, accepted in 1861, to those accepted as recently as last semester. Of the 2.3 million graduate works included in the database, ProQuest offers more than 1.9 million in full text formats. Of those, over 860,000 are available in PDF format. More than 60,000 dissertations and theses are added to the database each year.

If you have questions, please feel free to visit the ProQuest Web site - http://www.proquest.com - or call ProQuest Hotline Customer Support at 1-800-521-3042.