This thesis describes the experimental realisation and characterisation of three non-trivial trapping geometries for ultracold atoms. The double-well, ring and to some degree shell trap are examples of a highly versatile class of traps called time-averaged adiabatic potentials (TAAPs). In this experiment the TAAPs arise from the combination of three independent magnetic fields; a static quadrupole field dressed by a uniform radio-frequency field is time-averaged by a bias field oscillating at in the kHz regime. The result is a very smooth potential, within which ultracold atoms can be evaporatively cooled to quantum degeneracy, and subsequently manipulated into new geometries without destroying the quantum coherence.The vertically offset double-well potential provided the first example of ultracold atoms confined in a TAAP. The same potential is used to demonstrate efficient evaporative cooling across the Bose-Einstein condensate (BEC) phase transition using only the Landau-Zener loss mechanism. Switching off the time-averaging fields loads atoms from the double-well TAAP into the rf-dressed shell trap. A characterisation of this potential measured low heating rates and lifetimes of up to 58s. With efforts ongoing to increase the trap anisotropy, this potential shows promise for research into the static and rapidly rotating 2D systems. In the presence of a single time-averaging field, the shell geometry is transformed into a ring-shaped trap with an adjustable radius. The ring trap can be controllably tilted and progress towards multiply connected condensates is being made. A rotation scheme to spin up atoms in the ring trap has been demonstrated, presenting the opportunity to investigate the dynamics of superflow in degenerate quantum gases.This thesis describes the experimental realisation and characterisation of three non-trivial trapping geometries for ultracold atoms. The double-well, ring and to some degree shell trap are examples of a highly versatile class of traps called time-averaged adiabatic potentials (TAAPs). In this experiment the TAAPs arise from the combination of three independent magnetic fields; a static quadrupole field dressed by a uniform radio-frequency field is time-averaged by a bias field oscillating at in the kHz regime. The result is a very smooth potential, within which ultracold atoms can be evaporatively cooled to quantum degeneracy, and subsequently manipulated into new geometries without destroying the quantum coherence.The vertically offset double-well potential provided the first example of ultracold atoms confined in a TAAP. The same potential is used to demonstrate efficient evaporative cooling across the Bose-Einstein condensate (BEC) phase transition using only the Landau-Zener loss mechanism. Switching off the time-averaging fields loads atoms from the double-well TAAP into the rf-dressed shell trap. A characterisation of this potential measured low heating rates and lifetimes of up to 58s. With efforts ongoing to increase the trap anisotropy, this potential shows promise for research into the static and rapidly rotating 2D systems. In the presence of a single time-averaging field, the shell geometry is transformed into a ring-shaped trap with an adjustable radius. The ring trap can be controllably tilted and progress towards multiply connected condensates is being made. A rotation scheme to spin up atoms in the ring trap has been demonstrated, presenting the opportunity to investigate the dynamics of superflow in degenerate quantum gases.

Jan 1, 20110 citations

Experimental Progress Toward Trapping Atoms in Novel Geometries

Hong Jun Gao, Matthew Pasienski, Matthew White +1 more

Bulletin of the American Physical SocietyMay 17, 20060 citations

Trapping ultracold atoms in a time-averaged adiabatic potential

M. Gildemeister, E. Nugent, Benjamin E. Sherlock +3 more

We report an experimental realization of ultracold atoms confined in a time-averaged, adiabatic potential (TAAP). This trapping technique involves using a slowly oscillating ( $~$ kHz) bias field to time-average the instantaneous potential given by dressing a bare magnetic potential with a high-frequency ( $~$ MHz) magnetic field. The resultant potentials provide a convenient route to a variety of trapping geometries with tunable parameters. We demonstrate the TAAP trap in a standard time-averaged orbiting potential trap with additional Helmholtz coils for the introduction of the radio frequency dressing field. We have evaporatively cooled $5\ifmmode\times\else\texttimes\fi{}{10}^{4}$ atoms of $^{87}\mathrm{Rb}$ to quantum degeneracy and observed condensate lifetimes of longer than $3$ s.We report an experimental realization of ultracold atoms confined in a time-averaged, adiabatic potential (TAAP). This trapping technique involves using a slowly oscillating ($~$kHz) bias field to time-average the instantaneous potential given by dressing a bare magnetic potential with a high-frequency ($~$MHz) magnetic field. The resultant potentials provide a convenient route to a variety of trapping geometries with tunable parameters. We demonstrate the TAAP trap in a standard time-averaged orbiting potential trap with additional Helmholtz coils for the introduction of the radio frequency dressing field. We have evaporatively cooled $5\ifmmode\times\else\texttimes\fi{}{10}^{4}$ atoms of $^{87}\mathrm{Rb}$ to quantum degeneracy and observed condensate lifetimes of longer than $3$ s.

arXiv:0912.3393Physical Review AMar 22, 201032 citations

Time-dependent trapping of a molecule

Mark R. A. Shegelski, Joshua Pittman, Rob Vogt +1 more

The European Physical Journal PlusFeb 1, 20124 citations

Time-averaged adiabatic ring potential for ultracold atoms

Benjamin E. Sherlock, M. Gildemeister, E. Owen +2 more

We report the experimental realization of a versatile ring trap for ultracold atoms. The ring geometry is created by the time-averaged adiabatic potential resulting from the application of an oscillating magnetic bias field to a rf-dressed quadrupole trap. Lifetimes for a Bose-Einstein condensate in the ring exceed $11\mathrm{s}$ and the ring radius was continuously varied from $50 \ensuremath{\mu}\text{m}$ to $262 \ensuremath{\mu}\text{m}$. An efficient method of loading the ring from a conventional time-averaged orbiting potential trap is presented together with a rotation scheme which introduces angular momentum into the system. The ring presents an opportunity to study the superfluid properties of a condensate in a multiply connected geometry and also has applications for matter-wave interferometry.We report the experimental realization of a versatile ring trap for ultracold atoms. The ring geometry is created by the time-averaged adiabatic potential resulting from the application of an oscillating magnetic bias field to a rf-dressed quadrupole trap. Lifetimes for a Bose-Einstein condensate in the ring exceed $11\mathrm{s}$ and the ring radius was continuously varied from $50 \ensuremath{\mu}\text{m}$ to $262 \ensuremath{\mu}\text{m}$. An efficient method of loading the ring from a conventional time-averaged orbiting potential trap is presented together with a rotation scheme which introduces angular momentum into the system. The ring presents an opportunity to study the superfluid properties of a condensate in a multiply connected geometry and also has applications for matter-wave interferometry.

arXiv:1102.2895Physical Review AApr 18, 2011154 citations

We report an experimental realization of ultracold atoms confined in a time-averaged, adiabatic potential (TAAP). This trapping technique involves using a slowly oscillating (

~

kHz) bias field to time-average the instantaneous potential given by dressing a bare magnetic potential with a high-frequency (

~

MHz) magnetic field. The resultant potentials provide a convenient route to a variety of trapping geometries with tunable parameters. We demonstrate the TAAP trap in a standard time-averaged orbiting potential trap with additional Helmholtz coils for the introduction of the radio frequency dressing field. We have evaporatively cooled $5\ifmmode\times\else\texttimes\fi{}{10}^{4}$ atoms of

^{87}\mathrm{Rb}

to quantum degeneracy and observed condensate lifetimes of longer than

3

11\mathrm{s}

and the ring radius was continuously varied from $50 \ensuremath{\mu}\text{m}$ to $262 \ensuremath{\mu}\text{m}$. An efficient method of loading the ring from a conventional time-averaged orbiting potential trap is presented together with a rotation scheme which introduces angular momentum into the system. The ring presents an opportunity to study the superfluid properties of a condensate in a multiply connected geometry and also has applications for matter-wave interferometry.