We report the first realization of an optical dipole trap (ODT) for ultracold mercury atoms, overcoming the challenge posed by the exceptionally low polarizability of Hg and the resulting weak optical trapping potential. We demonstrate the transfer of six naturally abundant Hg isotopes from a magneto-optical trap (MOT) into the ODT and characterize its loading dynamics, trap depth, and lifetime. Confinement of dense samples of ultracold Hg opens new opportunities for studies of isotope-dependent collisions and photoassociation and provides a route toward quantum degeneracy.
We demonstrate efficient loading of an Yb three-dimensional magneto-optical trap (3D MOT) on the 1S0 → 1P1 transition. The experiment employs a two-dimensional magneto-optical trap (2D MOT) as an efficient cold atom source. Through optimization of the 2D MOT, auxiliary Zeeman slower, and push beam parameters that govern atomic capture, we achieve an atomic loading rate of 5 × 106 atoms/s in the 3D MOT, with approximately ∼107 trapped atoms. Our experimental results confirm the successful transfer of a substantial number of atoms from the 2D region to the science chamber via the push beam, providing an experimental foundation for subsequent implementation of narrow-line MOT and two-color MOT.
We demonstrate an efficient scheme for continuous trap loading based upon spatially selective optical pumping. We discuss the case of
1S0 calcium atoms in an optical dipole trap (ODT), however, similar strategies should be applicable to a wide range of atomic species, which do not permit efficient conventional trap loading. Our starting point is a moderately cold $(\ensuremath{\approx}300\phantom{\rule{0.3em}{0ex}}\ensuremath{\mu}\mathrm{K})$ and dense $(\ensuremath{\approx}9\ifmmode\times\else\texttimes\fi{}{10}^{9}\phantom{\rule{0.3em}{0ex}}{\mathrm{cm}}^{\ensuremath{-}3})$ reservoir of metastable
3P2 atoms in a magneto-optic trap (triplet MOT). A focused
532nm laser beam produces a strongly elongated optical potential for
1S0 atoms with up to $350\phantom{\rule{0.3em}{0ex}}\ensuremath{\mu}\mathrm{K}$ well depth. A weak focused laser beam at
430nm, carefully superimposed upon the ODT beam, selectively pumps the
3P2 atoms inside the capture volume to the singlet state, where they are confined by the ODT. The triplet MOT perpetually refills the capture volume with
3P2 atoms, thus providing a continuous stream of cold atoms into the ODT at a rate of ${10}^{7}\phantom{\rule{0.3em}{0ex}}{\mathrm{s}}^{\ensuremath{-}1}$. Limited by evaporation loss, in
200ms we typically load $5\ifmmode\times\else\texttimes\fi{}{10}^{5}$ atoms with $3.5\ifmmode\times\else\texttimes\fi{}{10}^{10}\phantom{\rule{0.3em}{0ex}}{\mathrm{cm}}^{\ensuremath{-}3}$ peak density and axial and radial temperatures of 300 and $85\phantom{\rule{0.3em}{0ex}}\ensuremath{\mu}\mathrm{K}$, respectively. After terminating the loading we observe evaporation during
50ms, typically leaving us with
105 atoms with nearly equal radial and axial temperatures close to $40\phantom{\rule{0.3em}{0ex}}\ensuremath{\mu}\mathrm{K}$ and a peak density of $5\ifmmode\times\else\texttimes\fi{}{10}^{11}\phantom{\rule{0.3em}{0ex}}{\mathrm{cm}}^{\ensuremath{-}3}$. A simple model is presented, which identifies the relevant physical mechanisms of the loading and decay dynamics. We point out that a comparable scheme could be employed to load a dipole trap with
3P0 atoms.
We report theoretical studies of an ef ficient accumulation of 225 Ra atoms in a magneto-optical trap (MOT) from an atomic beam. The number of atoms in the trap is limited due to the large leakage into metastable D states from the cooling transition and the loss mechanism from collisions with the background gases and with other elements in the atomic beam. We propose a setup consisting of an ef ficient Zeeman slower, an optical atomic beam de flector, and an EggMOT, which provides a large capture velocity, e.g. the Zeeman slower capture velocity of 581 ms 1 and the MOT capture velocity of 46 ms 1 . Furthermore, the pure slow atomic beam produced by the optical atomic beam de flector can maximize the number of trapped atoms and their lifetime in a ultra high vacuum chamber by minimizing the collisional loss. Our proposed setup allows for the search for a permanent electric dipole moment based on laser-cooled and trapped radium atoms with improved sensitivity.
As part of an effort to measure parity non-conserving atomic transition rates in a series of Cs radioisotopes, the authors are working on the efficient coupling of a magneto-optical trap (MOT) to a mass separator. They have established a test stand for optical trapping which is used for the off-line development of a high-efficiency MOT. Their trap features a dry-film coated cell with large (5 cm) windows to permit the use of large diameter, high power laser beams to increase the efficiency of the trapping process. Studies of the effect of detuning, magnetic field gradient, laser beam intensity and different beam sizes on the number of trapped atoms are presented.
We report a two-chambered, differentially pumped system that permits rapid collection of trapped atoms with a vapor cell magneto-optical trap (MOT) and efficient transfer of these atoms to a second MOT in a lowerpressure chamber. During the transfer the atoms are guided down a long, thin tube by a magnetic potential, with 90(15%) transfer efficiency. By multiply loading, we accumulate and hold as many as 30 times the number collected by the vapor cell MOT. By thus separating the collection and holding functions of a MOT, we can collect as many as 1.5(0.6) x 10(10) rubidium atoms and hold them for longer than 100 s, using inexpensive low-power diode lasers.