We report on the design and construction of a versatile setup for experiments with ultracold lithium (Li) gases. We discuss our methods to prepare an atomic beam and laser cool it in a Zeeman slower and a subsequent magneto-optical trap, which rely on established methods. We focus on our laser system based on a stable interference-filter-stabilized, linear-extended-cavity diode laser, so far unreported for lithium wavelengths. Moreover, we describe our optical setup to combine various laser frequencies for cooling, manipulation, and detection of Li atoms. We characterize the performance of our system preparing degenerate samples of Li atoms via forced evaporation in a hybrid crossed-beam optical-dipole trap plus confining magnetic trap. Our apparatus allows one to produce quantum gases of N ≈ 105…106 fermionic lithium-6 atoms at nanokelvin temperatures in cycle times below 10 s. Our optical system is particularly suited to study the dynamics of fermionic superfluids in engineered optical potentials.
REFERENCES
The names “cooling” and “repumping” transition follow the usual convention and reflect the similarity to laser cooling of other alkali atoms.
This potential strictly holds only for a two-level system. This approximation is fulfilled in our case as the D2 line fine-structure splitting is small compared to the laser detuning and polarizabilities, for all other transitions in lithium are negligible compared to the D2 transition.
For condensate fractions above 0.5, a thermal fraction cannot be reliably fitted any more.
