Resonant Scattering Phase Shifts of Ultracold Cesium and Their Energy Dependence
Open Access
Author:
Martin-wells, Ross Brandoch
Graduate Program:
Physics
Degree:
Doctor of Philosophy
Document Type:
Dissertation
Date of Defense:
December 14, 2012
Committee Members:
Kurt Gibble, Dissertation Advisor/Co-Advisor David Weiss, Committee Member Susan E Trolier Mckinstry, Committee Member Kenneth O'hara, Committee Member
This dissertation describes the first measurement of an atomic Feshbach resonance
as a function of the collision energy between two clouds of ultracold cesium atoms.
The resonance is observed as a large phase excursion in the s-wave collisional phase
shift. The collision energy between two ultracold clouds of cesium in a juggling
atomic fountain is adjusted from 12-50 µK in five energy steps. The magnetic field
is tuned each collision energy from 0-1.8G to see several discernible resonances.
Accurately measuring the position and width of Feshbach resonances can place
stringent limits on the time variation of fundamental constants.
Atoms are prepared in a superposition of the clock states of cesium and scatter
off target atoms in different states. We observe the scattering phase shift due to
the interaction of the superposition with the target atoms near resonances.
This dissertation also includes: a detailed procedure that traces the course
from atom cooling and launching to analysis of the collision data, descriptions of
changes made to the apparatus, brief explanations of the laser cooling techniques
employed, and the basic quantum scattering theory necessary to understand the
experiment.
