Reservoir spectroscopy of 5s5p 3^3P2_2 - 5snnd 3^3D1,2,3_{1,2,3} transitions in strontium

We perform spectroscopy on the optical dipole transitions 5s5p $^3$P$_2$ - 5s$n$d $^3$D$_{1,2,3}$, $n \in (5,6)$, for all stable isotopes of atomic strontium. We develop a new spectroscopy scheme, in which atoms in the metastable $^3$P$_2$ state are stored in a reservoir before being probed. The method presented here increases the attained precision and accuracy by two orders of magnitude compared to similar experiments performed in a magneto-optical trap or discharge. We show how the state distribution and velocity spread of atoms in the reservoir can be tailored to increase the spectroscopy performance. The absolute transition frequencies are measured with an accuracy of 2 MHz. The isotope shifts are given to within 200 kHz. We calculate the $A$ and $Q$ parameters for the hyperfine structure of the fermionic isotope at the MHz-level. Furthermore, we investigate the branching ratios of the $^3$D$_{J}$ states into the $^3$P$_{J}$ states and discuss immediate implications on schemes of optical pumping and fluorescence detection.Comment: 15 pages, 7 figures, 4 table

Degenerate quantum gases of strontium

Degenerate quantum gases of alkaline-earth-like elements open new opportunities in research areas ranging from molecular physics to the study of strongly correlated systems. These experiments exploit the rich electronic structure of these elements, which is markedly different from the one of other species for which quantum degeneracy has been attained. Specifically, alkaline-earth-like atoms, such as strontium, feature metastable triplet states, narrow intercombination lines, and a non-magnetic, closed-shell ground state. This review covers the creation of quantum degenerate gases of strontium and the first experiments performed with this new system. It focuses on laser-cooling and evaporation schemes, which enable the creation of Bose-Einstein condensates and degenerate Fermi gases of all strontium isotopes, and shows how they are used for the investigation of optical Feshbach resonances, the study of degenerate gases loaded into an optical lattice, as well as the coherent creation of Sr_2 molecules.Comment: Review paper, 43 pages, 24 figures, 249 reference

Creation of ultracold Sr2 molecules in the electronic ground state

We report on the creation of ultracold 84Sr2 molecules in the electronic ground state. The molecules are formed from atom pairs on sites of an optical lattice using stimulated Raman adiabatic passage (STIRAP). We achieve a transfer efficiency of 30% and obtain 4x10^4 molecules with full control over the external and internal quantum state. STIRAP is performed near the narrow 1S0-3P1 intercombination transition, using a vibrational level of the 0u potential as intermediate state. In preparation of our molecule association scheme, we have determined the binding energies of the last vibrational levels of the 0u, 1u excited-state, and the 1\Sigma_g^+ ground-state potentials. Our work overcomes the previous limitation of STIRAP schemes to systems with Feshbach resonances, thereby establishing a route that is applicable to many systems beyond bi-alkalis.Comment: 7 pages, 7 figures, 3 table

Bose-Einstein condensation of 86Sr

We report on the attainment of Bose-Einstein condensation of 86Sr. This isotope has a scattering length of about +800 a0 and thus suffers from fast three-body losses. To avoid detrimental atom loss, evaporative cooling is performed at low densities around 3x10^12 cm^-3 in a large volume optical dipole trap. We obtain almost pure condensates of 5x10^3 atoms.Comment: 4 pages, 3 figure