Novel Trapping Techniques For Shaping Bose-Einstein Condensates
Name
Micah Boyd TR#720.pdf
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3.84 MB
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Adobe PDF
Checksum (MD5)
7c8f9d52f12fa621c6440e1acd22e191
Author(s)
Boyd, Micah
Date Issued
February 7, 2007
Series/Report no.
Technical Report (Massachusetts Institute of Technology, Research Laboratory of Electronics);
720
Abstract
A combination of radio frequency radiation and magnetic field gradients was used to
trap atoms in dressed states. In a magnetic field with a quadrupole minimum, RF
fields resonant with the (|F,mf i) |1,−1i ! |1, 0i transition trapped the atoms on
the surface of a sphere, and gravity caused the atoms to pool at the bottom of the
sphere. BECs were transferred into this dressed Zeeman trap with 100% efficiency,
with lifetimes of up to 30 s, and trapping frequencies of up to 250 Hz were measured.
A hard disk platter with a specially written magnetic pattern was used to generate
magnetic fields to confine atoms tightly. Detrimental interactions with the surface
were avoided by using an extremely thin film with a large magnetic remnant. BECs
of up to 5×104 atoms were produced in cigar shaped traps 40 µm above the surface,
and trap frequencies up to 5 kHz were measured. After evaporation, condensed clouds
moved closer to the surface to probe imperfections in the magnetic potential, revealing
defects at distances closer than 35 µm. Finally, BECs were dropped from a height of
350 µm in an attempt to achieve specular reflection, but a large amount of dispersion
was observed.
Finally, BECs were loaded into a three-dimensional optical lattice, and a quantum
phase transition from a superfluid to a Mott insulator was observed. Using microwave
spectroscopy, the density dependent “clock shift” was was found to depend on the
occupation number of the wells. The singly occupied lattice sites were then investigated
as an atomic clock system with no density shift. Linewidths as small as 1 Hz
FWHM out of 6.8 GHz are comparable to current atomic frequency standards.
Description
Thesis Supervisor: Wolfgang Ketterle
Title: John D. MacAurthur Professor of Physics
Thesis Supervisor: David E. Pritchard
Title: Cecil and Ida Green Professor of Physics
MIT Department
Massachusetts Institute of Technology. Research Laboratory of Electronics
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