Learn More
Feshbach resonances are the essential tool to control the interaction between atoms in ultracold quantum gases. They have found numerous experimental applications, opening up the way to important breakthroughs. This Review broadly covers the phenomenon of Feshbach resonances in ultracold gases and their main applications. This includes the theoretical(More)
The observation of the superfluid to Mott insulator phase transition of ultracold atoms in optical lattices was an enabling discovery in experimental many-body physics, providing the first tangible example of a quantum phase transition (one that occurs even at zero temperature) in an ultracold atomic gas. For a trapped gas, the spatially varying local(More)
We investigate the stability of magnetically trapped atomic Bose-Einstein condensates and thermal clouds near the transition temperature at small distances 0.5 microm< or =d< or =10 microm from a microfabricated silicon chip. For a 2 microm thick copper film, the trap lifetime is limited by Johnson noise induced currents and falls below 1 s at a distance of(More)
An ultracold molecular quantum gas is created by application of a magnetic field sweep across a Feshbach resonance to a Bose-Einstein condensate of cesium atoms. The ability to separate the molecules from the atoms permits direct imaging of the pure molecular sample. Magnetic levitation enables study of the dynamics of the ensemble on extended time scales.(More)
We report on the optimized production of 1 a Bose-Einstein condensate of cesium atoms using an 2 optical trapping approach. Based on an improved trap 3 loading and evaporation scheme we obtain more than 10 5 4 atoms in the condensed phase. To test the tunability of 5 the interaction in the condensate we study the expansion 6 of the condensate as a function(More)
We observe several Feshbach resonances in magnetic fields below 40 G for Cs atoms trapped in a 1D optical lattice. One resonance occurs in the lowest-energy ground state F ෇ 3, m F ෇ 3 which is stable against inelastic binary collisions. This opens new possibilities for Bose condensation of Cs. When the elastic collision rate far exceeds the radial(More)
The collective behaviour of a many-body system near a continuous phase transition is insensitive to the details of its microscopic physics; for example, thermodynamic observables follow generalized scaling laws near the phase transition. The Berezinskii-Kosterlitz-Thouless (BKT) phase transition in two-dimensional Bose gases presents a particularly(More)
We measure high-resolution Feshbach resonance spectra for ultracold cesium atoms colliding in different hyperfine and magnetic sublevels. More than 25 resonances are observed for magnetic fields up to 230 G and their positions are measured with an accuracy down to 0.03 G. From these spectra several ground-state molecular interaction parameters can be(More)
We demonstrate a simple, general purpose method to cool neutral atoms. A sample containing 3 3 10 8 cesium atoms prepared in a magneto-optical trap is cooled and simultaneously spin polarized in 10 ms at a density of 1.1 3 10 11 cm 23 to a phase space density nl 3 dB ෇ 1͞500, which is almost 3 orders of magnitude higher than attainable in free space with(More)
We trap 10 7 cesium atoms in a far red detuned 1D optical lattice. With degenerate Raman sideband cooling we achieve a vibrational ground state population of 80% for the steep trapping direction. Collisional coupling enables us to cool the spin-polarized gas in 3D without loss of atoms to a peak phase space density of 1͞180 at a mean temperature of 2.8 mK(More)