Thesis (pdf) - Swinburne University of Technology

several million up to several hundred million atoms at these very low tem-
peratures. These break-throughs were rewarded with the award of the Nobel
prize for physics to Steven Chu, William Phillips and Claude Cohen-Tannoudji
in 1997. Having such cold atoms in such numbers allowed the creation of
several types of atom interferometers, which the field of metrology has bene-
fited from. These interferometers ranged from devices to measure the Earth’s
gravity [Pet99] and rotation [Gus97] to atomic clocks, which in principle are
interferometers only in the time domain [Rus98, Wil02], and to interferome-
ters that were used to measure atomic properties [Eks95] or natural constants
[Gup02]. All of these interferometers work with free atoms, either falling or
accelerated from the trap in which they were cooled, and the beamsplitters
needed for interferometry are created by light pulses and the change of the
atomic momentum on absorption of a photon [Kas91]. With the thermal mo-
tion and kinetic energy being greatly reduced, it became possible to trap and
confine large numbers of atoms with rather weak forces, stemming for example
from the interaction between a magnetic field and the magnetic moment of
an atom or from the interaction of the induced atomic electric dipole-moment
with an electro-magnetic field. With these magnetic and optical traps even
more versatile atom interferometer set-ups are possible.
Two main implementations of atom interferometers have been proposed: in
the first example, an otherwise stationary trap is split into two, held there and
recombined [Hin01]. The second example works with confined atoms that pass
through wave guides and beam splitters. Only recently it has become possible
to create these time dependent (in the first case) or spatially dependent (in the
second case) potentials. Here either micron-sized optics and lenses are used to
create optical traps which can be split and recombined [Dum02b] or waveguides
are constructed [Dum02a]. For magnetic traps, the proposal [Wei95, Thy99]
and realisation [Rei99, Ott01] of the so-called “atom chip” made the tailoring
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