Carlo Sias has been awarded with a SIR ("Scientific Independence of young Researchers") grant from MIUR ("Italian Ministry for Education and Research") for the development of the Ba+/Li experiment! |
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Using the inverse Abel transform, the in-situ 3D density profile of a cloud of two-state 6Li atoms trapped in a potential with cylindrical symmetry can be derived. Following [M. Ku et al., Science 335, 563 (2012)] we reconstruct the equation of state of the system. In particular, local pressure and compressibility have been obtained for the unitary Fermi gas, revealing the superfluid transition. |
The quest to develop new and efficient experimental schemes to produce large and highly degenerate fermionic samples is fundamental in the way of using them to study fermionic superfluidity with a high degree of control on properties as interaction strength and dimensionality. 6Li samples of two spin components offers a broad Feshbach resonance allowing a good tenability of the interactions and the ability to investigate superfluidity across the BEC-BCS crossover. On the other way, standard laser cooling configurations are not efficient due to the lack of sub-Doppler cooling mechanism on the D2 line. 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 μK 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 5×105 molecules and weakly interacting degenerate Fermi gases of 7×105 atoms at T/TF A. Burchianti et al. |
After testing the first cooling stages the experiment has been moved from LENS to the CNR research area in Pisa. |
Anderson localization is a universal phenomenon affecting non-interacting quantum particles in a disordered environment. In three spatial dimensions, theory predicts a quantum phase transition from localization to diffusion at a critical energy, the mobility edge, which depends on the disorder strength. Although it has been recognized already long ago as a prominent feature of disordered systems, a complete experimental characterization of the mobility edge is still missing. Here we report the measurement of the mobility edge for ultracold atoms in a disordered potential created by laser speckles. We are able to control both the disorder strength and the energy of the system, so as to probe the position of the localization threshold in the disorder–energy plane. Our results might allow a direct experiment–theory comparison, which is a prerequisite to study the even more challenging problem of disorder and interactions. G. Semeghini, et al., |