Measuring Atomic Properties with an Atom Interferometer
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TonyRobertsTR660.pdf
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Author(s)
Roberts, Tony David
Date Issued
June 28, 2006
Series/Report no.
Technical Report (Massachusetts Institute of Technology, Research Laboratory of Electronics);
660
Abstract
Two experiments are presented which measure atomic properties using an atom interferometer. The interferometer splits the sodium de Broglie wave into two paths,
one of which travels through an interaction region. The paths are recombined, and
the interference pattern exhibits a phase shift depending on the strength of the interaction.
In the first experiment, the interaction involves a gas. De Broglie waves traveling
through the gas experience a phase shift represented by an index of refraction. By
measuring the index of refraction at various wavelengths, the predicted phenomenon
of glory oscillations in the phase shift has been observed for the first time. The
index of refraction has been measured for sodium atoms in gases of argon, krypton,
xenon, and nitrogen over a wide range of wavelength. These measurements offer
detailed insight into the interatomic potential between sodium atoms and the gases.
Theoretical predictions of the interatomic potentials are challenged by these results,
which should encourage a renewed effort to better understand these potentials.
The second experiment measures atomic polarizability with an atom interferometer. Here, the interaction is with an electric field; the atom experiences a phase shift
proportional to its energy inside the field. Previously, this method was used to per-
form the most accurate (< 1%) measurement of sodium polarizability. The precision
was limited, however, by the spread of velocities in the atomic beam|the phase shift
is different depending on velocity, and the interference pattern is washed out. This
thesis presents a new technique to "rephase" the interference pattern at large applied
fields, and demonstrates a measurement that is free of this limitation. In addition,
most of the systematic errors that plagued the previous polarizability measurement
are eliminated by the new technique, and an order of magnitude improvement in precision now appears quite feasible. The remaining systematic errors can be eliminated
by measuring the ratio of polarizabilities between two different atoms, a comparison
whose precision is better by another order of magnitude.
Description
Thesis Supervisor: David E. Pritchard
Title: Professor of Physics
MIT Department
Massachusetts Institute of Technology. Research Laboratory of Electronics
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