Thesis (pdf) - Swinburne University of Technology

Chapter 2
Theoretical Background
In the branch of atomic physics called “Atom Optics” we deal with cold and
ultra-cold atoms. To exploit the wave like properties of atoms [de 24] the
thermal de Broglie wavelength of the atoms λdB defined by
λdB = h/p = h/ � 3m · kBT (2.1)
has to be increased by cooling down the atoms while confining them in a trap.
The mechanisms of how to cool and how to trap these atoms are thus of main
interest. To understand these mechanisms, one has to understand the principal
interactions between the atoms and the fields that are used to trap and cool
the atoms. Using light and magnetic fields for these purposes, we are in the
fortunate position that this theory is well understood.
This chapter will introduce the general theory and emphasize and explain
certain points in more detail, which are needed for a full understanding of the
experiments that are the main part of this thesis. This chapter starts with
an explanation of the interaction between an atom and electromagnetic waves.
Here we need to differ between two main interactions: one that allows the
trapping of atoms, and one that allows us to cool and to detect our atomic
sample. The detection of atoms will also be addressed here. The next section
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