Partial level scheme of Yb. Only the lowest states in the triplet and singlet manifolds, which are relevant to laser cooling and precision spectroscopy, are shown. 32–35 The hyperfine structure of the 1 P 1 state is given for the fermionic isotope 173Yb.
Sketch of the 2D-/3D-MOT system. (a) The 3D-MOT using the intercombination transition 1 S 0 → 3 P 1 is loaded from a 2D-MOT operated close to the principal transition 1 S 0 → 1 P 1 in a separate glass cell. Both cells are mounted to a central vacuum chamber and connected by a dual differential pumping stage. A pushing beam enhances the loading rate of the 3D-MOT. (b) Top-view of (a). The 2D-MOT is loaded transversely from the beam of atoms emitted by a dispenser.
Loading rate of a 3D-MOT of 174Yb as a function of magnetic field gradient and detuning of the 2D-MOT. Numerical simulations (a) for a capture velocity of 10 m/s of the 3D-MOT and corresponding experimental results (b). Optimal loading is achieved at a gradient of about 55 G/cm and a detuning of Δ2D = −1.2Γ.
Loading rate of a 174Yb 3D-MOT as a function of its capture velocity. Results of numerical simulations are shown for magnetic field gradients of 40 G/cm (⧫), 55 G/cm (•), and 70 G/cm (■) at detunings of −1.4Γ, −1.2Γ, and −1.1Γ, respectively, yielding optimal maximum loading rates.
Sketch of the CAD model of the 2D-/3D-MOT apparatus.
3D-MOT loading rate of 174Yb measured as a function of the FWHM ξ of the broadened laser spectrum. The high frequency edge of the spectrum is kept at a constant detuning from the 1 S 0 → 3 P 1 resonance frequency.
3D-MOT loading rate of 174Yb measured as a function of power in the pushing beam. Loading rates are normalized to the value without a pushing beam.
Absorption images of quantum degenerate gases of Yb taken after time of flight (TOF) and density profiles (circles) integrated along the vertical axis along with fits of appropriate model functions (red lines). (a) Partially condensed Bose gas of 174Yb (20 ms TOF). The bimodal fit is composed of a Bose distribution and a Thomas-Fermi density distribution of a harmonic trap potential for the condensate fraction. (b) Nearly pure Bose-Einstein condensate of 174Yb (20 ms TOF) with a fitted Thomas-Fermi density distribution of a harmonic trap potential. (c) Degenerate Fermi gas of 173Yb (8 ms TOF). The fit shows the distribution of a non-interacting Fermi gas with T/T F = 0.32(3).
Article metrics loading...
Full text loading...