An all optical BEC apparatus for the investigation of magnetic order in spinor atomic gases in ultralow magnetic fields
Hughes, Joshua Alan
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Bose-Einstein condensates (BECs) of spinor atomic gases have become powerful tools in quantum simulation experiments. Quantum magnetism, in particular, is a field of study that is difficult to simulate in the solid state but is readily accessible in BECs. However, there are still many quantum magnetic effects predicted to occur in spinor BECs that have yet to be observed in the laboratory. This is due to the presence of typical background magnetic fields which are sufficiently large to suppress these predicted phenomena. We have designed and built an apparatus to test a wide range of quantum magnetism parameters in the ultralow field regime. We use a two chamber ultra-high vacuum apparatus to precool atoms in a vapor cell magneto-optical trap and transfer the atoms into an ultra high vacuum magneto-optical trap, where they are efficiently loaded into a tightly confining, large volume optical dipole trap. The dipole trap will eventually be used to realize an all-optical BEC located inside a multi-layer mu-metal shield that reduces the background magnetic field to below 10^-6 Gauss around the condensate region while still allowing good optical access for imaging and measurements. We have performed measurements of microwave-driven Rabi oscillations in the dipole trap to test the feasibility of ultralow magnetic field measurements inside the magnetic shield. We have also developed a method to dynamically control the aspect ratio of the BEC using a crossed beam dipole trap configuration we call a ``scissor trap'.