arXiv subjects

E. Nugent

Publications and source records attributed to E. Nugent.

3 recordsLinked to original sources

arXiv2011

Time-averaged adiabatic ring potential for ultracold atoms

We report the experimental realisation 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 11s and the ring radius was continuously varied from 50$μ$m to 261$μ$m. An efficient method of loading the ring from a conventional TOP 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.

cond-mat.quant-gas↗

arXiv2009

Trapping Ultracold Atoms in a Time-Averaged Adiabatic Potential

We report the first experimental realization of ultracold atoms confined in a time-averaged, adiabatic potential (TAAP). This novel trapping technique involves using a slowly oscillating ($\sim$ kHz) bias field to time-average the instantaneous potential given by dressing a bare magnetic potential with a high frequency ($\sim$ 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 $\times 10^4$ atoms of $^{87}$Rb to quantum degeneracy and observed condensate lifetimes of over \unit[3]{s}.-

cond-mat.quant-gas↗

arXiv2004

Quasi-2D Confinement of a BEC in a Combined Optical and Magnetic Potential

We have added an optical potential to a conventional Time-averaged Orbiting Potential (TOP) trap to create a highly anisotropic hybrid trap for ultracold atoms. Axial confinement is provided by the optical potential; the maximum frequency currently obtainable in this direction is 2.2 kHz for rubidium. The radial confinement is independently controlled by the magnetic trap and can be a factor of 700 times smaller than in the axial direction. This large anisotropy is more than sufficient to confine condensates with ~10^5 atoms in a Quasi-2D (Q2D) regime, and we have verified this by measuring a change in the free expansion of the condensate; our results agree with a variational model.

cond-mat.other↗