We present new techniques in cooling 39 K atoms using laser light close to the D1 transition.First, a new compressed-MOT configuration is taking advantage of gray-molasses-type cooling induced by blue-detuned D1 light.It yields an optimized density of atoms.Then, we use pure D1 gray molasses to further cool the atoms to an ultra-low temperature of 6 μK.The resulting phase-space density is 2 × 10 -4 and will ease future experiments with ultracold potassium.As an example, we use it to directly load up to 3 × 10 7 atoms in a far detuned optical trap, a result that opens the way to the all-optical production of potassium degenerate gases.
In this work we document the first measure of Feshbach resonances in our laboratory utilizing potassium 39 in the state F = 1, m F = 0. We submitted the 39K atoms trapped in an optical trap to a homogeneous magnetic field in the range of up to 800 Gauss, where are expected resonances for the species in the |F = 1 manifold.Those are the first steps to come up with a machine capable of using this technique for different and innovative studies on superfluidity in a mixture of quantum gases.In our case, we use the same pair of coils both to obtain different magnetic field gradients (phase of MOT and MT), in anti-Helmholtz configuration, as well as to obtain a homogeneous magnetic field (tuning the magnetic field around previewed resonance), in Helmholtz configuration.To make this possible, we have implemented a H-Bridge system, which consists in installing one of the coils in a system of power switches.We have prepared the atomic cloud since the MOT, passing through a Gray Molasses stage and reaching our Optical Dipole Trap with 10 6 atoms at 12 µK where we apply a homogeneous field and perform a loss spectroscopy.Here we will present the resonances we have obtained and its characterization.
We use a gray molasses operating on the
D1 atomic transition to produce degenerate quantum gases of
6Li with a large number of atoms. This sub-Doppler cooling phase allows us to lower the initial temperature of
109 atoms from 500 to 40 $\ensuremath{\mu}\mathrm{K}$ in 2 ms. We observe that
D1 cooling remains effective into a high-intensity infrared dipole trap where two-state mixtures are evaporated to reach the degenerate regime. We produce molecular Bose-Einstein condensates of up to 5 $\ifmmode\times\else\texttimes\fi{}$
105 molecules and weakly interacting degenerate Fermi gases of $7\ifmmode\times\else\texttimes\fi{}{10}^{5}$ atoms at
T/TF<0.1 with a typical experimental duty cycle of 11 s.