Ioffe-Pritchard Magnetic Trap Research Articles

Magnetic trapping of a cold Rb–Cs atomic mixture

We present an apparatus for the study of an ultracold gaseous atomic mixture of 133Cs and 87Rb. The mixture is prepared using a double magneto-optical trap (MOT) system in which a two-species pyramid MOT acts as a source of cold atoms for a ‘science’ MOT. Measurements of the interspecies trap loss rate coefficients and in the science MOT are reported. After the initial MOT phase, atoms in the mixture are optically pumped into the magnetically trappable |F = 3, mF = −3⟩ and |F = 1, mF = −1⟩ states of Cs and Rb (respectively) and loaded into an Ioffe–Pritchard magnetic trap. We demonstrate a novel technique for limiting the interspecies loss rate in the science MOT by spatially separating the two trapped atom clouds, which greatly enhances the number of atoms which can be loaded into the magnetic trap.

Vortex Pump for Dilute Bose-Einstein Condensates

The formation of vortices by topological phase engineering has been realized experimentally to create the first two- and four-quantum vortices in dilute atomic Bose-Einstein condensates. We consider a similar system, but in addition to the Ioffe-Pritchard magnetic trap we employ an additional hexapole field. By controlling cyclically the strengths of these magnetic fields, we show that a fixed amount of vorticity can be added to the condensate in each cycle. In an adiabatic operation of this vortex pump, the appearance of vortices into the condensate is interpreted as the accumulation of a local Berry phase. Our design can be used as an experimentally realizable vortex source for possible vortex-based applications of dilute Bose-Einstein condensates.

Large atom number Bose-Einstein condensate machines

We describe experimental setups for producing large Bose-Einstein condensates of Na23 and Rb87. In both, a high-flux thermal atomic beam is decelerated by a Zeeman slower and is then captured and cooled in a magneto-optical trap. The atoms are then transferred into a cloverleaf-style Ioffe-Pritchard magnetic trap and cooled to quantum degeneracy with radio-frequency-induced forced evaporation. Typical condensates contain 20×106 atoms. We discuss the similarities and differences between the techniques used for producing large Rb87 and Na23 condensates in the context of nearly identical setups.

Bose–Einstein condensation of atomic hydrogen Feynman path integral approach

We study the ground state properties of Bose–Einstein condensation of atomic hydrogen in the Ioffe–Pritchard magnetic trap using many-body Feynman path integral theory, which leads to the calculation of the ground state energy and the wavefunction. We also calculate the size, peak condensate density and the value of the ground state energy, which are in good agreement with the experimental results obtained by laser spectroscopy of the 1S–2S transition.

Coreless vortex formation in a spinor Bose-Einstein condensate.

Coreless vortices were phase imprinted in a spinor Bose-Einstein condensate. The three-component order parameter of F=1 sodium condensates held in a Ioffe-Pritchard magnetic trap was manipulated by adiabatically reducing the magnetic bias field along the trap axis to zero. This distributed the condensate population across its three spin states and created a spin texture. Each spin state acquired a different phase winding which caused the spin components to separate radially.

Continuous loading of cold atoms into a Ioffe Pritchard magnetic trap

We present a robust continuous optical loading scheme for a Ioffe–Pritchard (IP) type magnetic trap (MT). Chromium atoms are cooled and trapped in a modified magneto-optical trap (MOT) consisting of a conventional 2D-MOT in the radial direction and an axial molasses. The MOT and IP trap share the same magnetic field configuration. Continuous loading of atoms into the IP trap is provided by radiative leakage from the MOT to a metastable level which is magnetically trapped and decoupled from the MOT light. We are able to accumulate 30 times more atoms in the MT than in the MOT. The absolute number of 2 × 10 8 atoms is limited by inelastic collisions. A model based on rate equations shows good agreement with the data. Our scheme can also be applied to other atoms with similar level structure like alkaline earth metals.

Imprinting vortices in a Bose-Einstein condensate using topological phases.

Vortices were imprinted in a Bose-Einstein condensate using topological phases. Sodium condensates held in a Ioffe-Pritchard magnetic trap were transformed from a nonrotating state to one with quantized circulation by adiabatically inverting the magnetic bias field along the trap axis. Using surface wave spectroscopy, the axial angular momentum per particle of the vortex states was found to be consistent with 2 variant Planck's over 2pi or 4 variant Planck's over 2pi, depending on the hyperfine state of the condensate.

Free expansion of a Bose-Einstein condensate from an Ioffe-Pritchard magnetic trap

rubidium-87 atoms released from an Ioffe–Pritchard magnetic trap is investigated experimentally. The expansion dynamics depend only on the trap frequencies, which are determined independently. The data are in good agreement with the expected expansion of a condensate, and are clearly distinct from the behaviour of a classical gas in the hydrodynamic regime.