G. Modugno

Collisional properties of ultracold K-Rb mixtures.

We determine the interspecies s-wave triplet scattering length a(3) for all K-Rb isotopic mixtures by measuring the elastic cross section for collisions between 41K and 87Rb in different temperature regimes. The positive value a(3)=+163(+57)(-12)a(0) ensures the stability against collapse of binary (41)K- (87)Rb Bose-Einstein condensates. For the fermion-boson mixture (40)K- (87)Rb, we obtain a large and negative scattering length which implies an efficient sympathetic cooling of the fermionic species down to the degenerate regime.

Fermi-Bose quantum degenerate ^40 K - ^87 Rb mixture with attractive interaction

We report on the achievement of simultaneous quantum degeneracy in a mixed gas of fermionic 40K and bosonic 87Rb. Potassium is cooled to 0.3 times the Fermi temperature by means of an efficient thermalization with evaporatively cooled rubidium. Direct measurement of the collisional cross-section confirms a large interspecies attraction. This interaction is shown to affect the expansion of the Bose-Einstein condensate released from the magnetic trap, where it is immersed in the Fermi sea.

Radio frequency selective addressing of localized atoms in a periodic potential.

We study the localization and addressability of ultracold atoms in a combined parabolic and periodic potential. Such a potential supports the existence of localized stationary states and we show that applying a radio frequency field allows us to selectively address atoms in these states. This method is used to measure the energy and momentum distribution of the atoms in the localized states. We also discuss possible extensions of this scheme to address and manipulate atoms in single lattice sites.

Tunable frequency-controlled laser source in the near ultraviolet based on doubling of a semiconductor diode laser

Continuously tunable ultraviolet laser radiation at 397 nm was generated by doubling the output of a semiconductor diode laser. The fundamental radiation was provided by a 150 mW AlGaAs laser diode injected by a low-power AlGaAs laser diode which was frequency stabilized by optical feedback using a new scheme of a miniature external cavity. Second-harmonic generation was produced in a lithium-triborate crystal placed in a compact enhancement cavity. The fundamental radiation was used for sub-Doppler spectroscopy of the Ar I 4s3P00−4p1P1 transition at 795 nm; the second-harmonic radiation was used for spectroscopy of the Ca II 42S1/2−42P1/2 transition at 397 nm.

Scissors mode of an expanding Bose-Einstein condensate

We study the scissors mode of a free-expanding Bose-Einstein condensate. We find that the irrotational character of the superfluid flow within the condensate has dramatic consequences on the evolution of the scissors oscillation. After a short expansion the oscillation is amplified and distorted, while asymptotically it recovers its initial sinusoidal behavior, with an enhanced amplitude. We investigate this phenomenon by using a technique to excite the scissors mode in a condensate held in a magnetostatic potential.

SUB-DOPPLER LASER COOLING OF FERMIONIC 40K ATOMS

We report laser cooling of fermionic

Expansion of a Fermi Gas Interacting with a Bose-Einstein Condensate

{}^{40}\mathrm{K}

Optical trapping of cold fermionic potassium for collisional studies

atoms, with temperatures down to

Atom Interferometry with a Weakly Interacting Bose Einstein Condensate

(15\ifmmode\pm\else\textpm\fi{}5) \ensuremath{\mu}\mathrm{K},

Bose-Einstein condensates and quantum degenerate Ferni gases in optical lattices

for an enriched sample trapped in a magneto-optical trap and additionaly cooled in optical molasses. This temperature is a factor of 10 below the Doppler-cooling limit and corresponds to an rms velocity within a factor of 2 of the lowest realizable rms velocity