No abstract available

[en] Two- and three-photon double ionization of atomic lithium by intense (I ≈ 10¹⁴ W/cm²) VUV light was investigated at the free electron laser in Hamburg (FLASH). Using a reaction microscope the recoil ion momentum distributions were recorded for two different photon energies of 50 and 59 eV. The former covers the case of non-resonant double ionization, whereas the latter gives rise to resonant excitation followed by double ionization. These reactions are of special interest as theoretical calculations for few-photon - few-electron reactions just become feasible for simple atomic targets.

[en] We present a comprehensive study of the Bose-Einstein condensate to Bardeen-Cooper-Schrieffer (BEC-BCS) crossover in fermionic ⁶Li using Bragg spectroscopy. A smooth transition from molecular to atomic spectra is observed with a clear signature of pairing at and above unitarity. These spectra probe the dynamic and static structure factors of the gas and provide a direct link to two-body correlations. We have characterized these correlations and measured their density dependence across the broad Feshbach resonance at 834 G

[en] We produce Bose-Einstein condensates of ⁶Li₂ molecules in a low power (22 W) crossed optical dipole trap. Fermionic ⁶Li atoms are collected in a magneto-optical trap from a Zeeman slowed atomic beam and then loaded into the optical dipole trap where they are evaporatively cooled to quantum degeneracy. Our simplified system offers a high degree of flexibility in trapping geometry for studying ultracold Fermi and Bose gases