Summary form only given. The importance of helium atoms in the metastable state 2/sup 3/S/sub 1/ (He*, lifetime 8000 s) for studies of ultracold atomic clouds in the quantum degeneracy regime has been pointed out. For /sup 4/He* Bose-Einstein condensation (BEC) is expected, whereas the /sup 3/He isotope allows the study of a fermionic system, if the technique of sympathetic cooling is feasible. We plan to reach the BEC transition using forced evaporative cooling in our magnetostatic trap (MST) of cloverleaf geometry.Summary form only given. The importance of helium atoms in the metastable state 2/sup 3/S/sub 1/ (He*, lifetime 8000 s) for studies of ultracold atomic clouds in the quantum degeneracy regime has been pointed out. For /sup 4/He* Bose-Einstein condensation (BEC) is expected, whereas the /sup 3/He isotope allows the study of a fermionic system, if the technique of sympathetic cooling is feasible. We plan to reach the BEC transition using forced evaporative cooling in our magnetostatic trap (MST) of cloverleaf geometry.

Conference on Lasers and Electro-OpticsAug 29, 20050 citations

Evaporative cooling of magnetically trapped hydrogen

Luiten, O.J., Werij, H.G.C., Reynolds, M.W. +3 more

Jan 1, 19940 citations

Magnetic trapping and evaporative cooling of metastable triplet helium

Norbert Herschbach, Paul J. J. Tol, Andrey Tychkov +2 more

A cloverleaf magnetic trap is loaded from a magneto-optical trap containing 2 × 10 9 helium atoms in the metastable 2 3 S 1 state. With optical molasses and a spin polarization pulse up to 1.5 × 10 9 atoms are magnetically trapped. The vacuum limited trap lifetime is ∼12 s. Compression in 0.5 s yields a density increase to 8 × 10 9 cm −3 . With rf-forced evaporation using an exponentially shaped frequency sweep with a 5 s time constant the phase space density is increased from 1 × 10 −7 to 4 × 10 −3 . The central density increases to 3 × 10 11 cm −3 , while an increase in elastic collision rate from 40 to 220 s −1 indicates runaway evaporation.A cloverleaf magnetic trap is loaded from a magneto-optical trap containing 2 × 10 9 helium atoms in the metastable 2 3 S 1 state. With optical molasses and a spin polarization pulse up to 1.5 × 10 9 atoms are magnetically trapped. The vacuum limited trap lifetime is ∼12 s. Compression in 0.5 s yields a density increase to 8 × 10 9 cm −3 . With rf-forced evaporation using an exponentially shaped frequency sweep with a 5 s time constant the phase space density is increased from 1 × 10 −7 to 4 × 10 −3 . The central density increases to 3 × 10 11 cm −3 , while an increase in elastic collision rate from 40 to 220 s −1 indicates runaway evaporation.

Journal of Optics B Quantum and Semiclassical OpticsApr 1, 200311 citations

Evaporative cooling of magnetically trapped atomic hydrogen

O.J. Luiten, H. G. C. Werij, M. W. Reynolds +3 more

Physica B Condensed MatterFeb 1, 19943 citations

Simple method for producing Bose–Einstein condensates of metastable helium using a single-beam optical dipole trap

Adonis Silva Flores, Hari Prasad Mishra, W. Vassen +1 more

We demonstrate a simple scheme to reach Bose–Einstein condensation (BEC) of metastable triplet helium atoms using a single-beam optical dipole trap with moderate power of less than 3 W. Our scheme is based on RF-induced evaporative cooling in a quadrupole magnetic trap and transfer to a single-beam optical dipole trap that is located below the magnetic trap center. We transfer $1\times 10^6$ atoms into the optical dipole trap, with an initial temperature of $$14\,\upmu\hbox{K}$$ , and observe efficient forced evaporative cooling both in a hybrid trap, in which the quadrupole magnetic trap operates just below the levitation gradient, and in the pure optical dipole trap, reaching the onset of BEC with $2\times 10^5$ atoms and a pure BEC of $5\times 10^4$ atoms. Our work shows that a single-beam hybrid trap can be applied for a light atom, for which evaporative cooling in the quadrupole magnetic trap is strongly limited by Majorana spin-flips, and the very small levitation gradient limits the axial confinement in the hybrid trap.We demonstrate a simple scheme to reach Bose–Einstein condensation (BEC) of metastable triplet helium atoms using a single-beam optical dipole trap with moderate power of less than 3 W. Our scheme is based on RF-induced evaporative cooling in a quadrupole magnetic trap and transfer to a single-beam optical dipole trap that is located below the magnetic trap center. We transfer $$1\times 10^6$$ atoms into the optical dipole trap, with an initial temperature of $$14\,\upmu\hbox{K}$$ , and observe efficient forced evaporative cooling both in a hybrid trap, in which the quadrupole magnetic trap operates just below the levitation gradient, and in the pure optical dipole trap, reaching the onset of BEC with $$2\times 10^5$$ atoms and a pure BEC of $$5\times 10^4$$ atoms. Our work shows that a single-beam hybrid trap can be applied for a light atom, for which evaporative cooling in the quadrupole magnetic trap is strongly limited by Majorana spin-flips, and the very small levitation gradient limits the axial confinement in the hybrid trap.

arXiv:1508.04019Applied Physics BOct 27, 20156 citations

1\times 10^6

atoms into the optical dipole trap, with an initial temperature of $$14\,\upmu\hbox{K}$$ , and observe efficient forced evaporative cooling both in a hybrid trap, in which the quadrupole magnetic trap operates just below the levitation gradient, and in the pure optical dipole trap, reaching the onset of BEC with

2\times 10^5

atoms and a pure BEC of

5\times 10^4

atoms. Our work shows that a single-beam hybrid trap can be applied for a light atom, for which evaporative cooling in the quadrupole magnetic trap is strongly limited by Majorana spin-flips, and the very small levitation gradient limits the axial confinement in the hybrid trap.