Time-averaged adiabatic ring potential for ultracold atoms

Abstract

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$\mu$m to 261$\mu$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

Coherent Stern–Gerlach momentum splitting on an atom chip

“…Pure static fields 20 or light fields 21,22 have also been used. However, practical atom chip schemes for interferometry with a wide dynamic range and versatile geometries are still very much sought after [23][24][25][26][27][28] . Such schemes may enable, for example, sensitive probing of classical or quantum properties of solid-state nanoscale devices and surface physics (for example, refs [29][30][31][32][33].…”

Rotating a Bose-Einstein condensate by shaking an anharmonic axisymmetric magnetic potential

“…We expect that our trapping potential might be deformed into a ring potential after the driving phase by applying an additional optical potential [48][49][50] or using RF-field dressing techniques [51,52], which would result in a giant vortex state [33,34]. Recently, Roncaglia et al [14] showed that a giant vortex state having a large angular momentum in a ring potential is adiabatically connected to the bosonic ν = 1/2 Laughlin state in a harmonic potential.…”

Species-selective confinement of atoms dressed with multiple radiofrequencies

“…This 'cross-talk' means that the position of the second species is also affected by the first rf component, and A relative displacement in the horizontal plane can also be achieved by manipulating the polarisation of the dressing rf field, as was previously demonstrated to tilt a single rf shell trap [30]. In this method a small vertical rf field of the form δB i sin (ω i t + φ)ê z is added to B rf , breaking the cylindrical symmetry of the coupling strength aboutê z for the i-th spheroid.…”

“…In this configuration, 85 Rb is near resonance with the field component of frequency ω 1 , and 87 Rb with that of ω 2 . Both species can be loaded simultaneously into these wells from a TimeOrbiting Potential trap, as previously demonstrated for 87 Rb in a rf-dressed potential formed with a single radiofrequency [30].…”

“…For numerical purposes here we shall consider the mixture of 85 Rb-87 Rb in their lower hyperfine states, labelling the isotopes A and B respectively so that g A F = −1/3 and g B F = −1/2. The discussion is furnished with numerical calculations based on the parameter range of an existing 87 Rb apparatus that is described in detail elsewhere [30]. This was recently used to implement rfdressed potentials with multiple frequency components for a single species [31].…”