We report the observation of the scissors mode of a Bose-Einstein condensed gas of 87Rb atoms in a magnetic trap, which gives direct evidence of superfluidity in this system. The scissors mode of oscillation is excited by a sudden rotation of the anisotropic trapping potential. For a gas above T(c) (normal fluid) we detect the occurrence of oscillations at two frequencies, with the lower frequency corresponding to the rigid body value of the moment of inertia. Well below T(c) the condensate oscillates at a single frequency, without damping, as expected for a superfluid.

We have investigated the formation of vortices by rotating the purely magnetic potential confining a Bose-Einstein condensate. We modified the bias field of an axially symmetric TOP trap to create an elliptical potential that rotates in the radial plane. This enabled us to study the conditions for vortex nucleation over a wide range of eccentricities and rotation rates.

We describe the design, construction and operation of a versatile dual-species Zeeman slower for both Cs and Yb, which is easily adaptable for use with other alkali metals and alkaline earths. With the aid of analytic models and numerical simulation of decelerator action, we highlight several real-world problems affecting the performance of a slower and discuss effective solutions. To capture Yb into a magneto-optical trap (MOT), we use the broad $^1S_0$ to $^1P_1$ transition at 399 nm for the slower and the narrow $^1S_0$ to $^3P_1$ intercombination line at 556 nm for the MOT. The Cs MOT and slower both use the D2 line ($6^2S_{1/2}$ to $6^2P_{3/2}$) at 852 nm. We demonstrate that within a few seconds the Zeeman slower loads more than $10^9$ Yb atoms and $10^8$ Cs atoms into their respective MOTs. These are ideal starting numbers for further experiments on ultracold mixtures and molecules.Comment: 15 pages, 15 figures, 4 tables, revtex4-

We present a simple technique for stabilization of a laser frequency off resonance using the Faraday effect in a heated vapor cell with an applied magnetic field. In particular we demonstrate stabilization of a 780 nm laser detuned up to 14 GHz from the 85 Rb D 2 5 2 S 1/2 F = 2 to 5 2 P 3/2 F ′ = 3 transition. Control of the temperature of the vapor cell and the magnitude of the applied magnetic field allows locking ∼6-14 GHz red and blue detuned from the atomic line. We obtain an rms fluctuation of 7 MHz over one hour without stabilization of the cell temperature or magnetic field.

No abstract

We report the observation of harmonic generation and strong nonlinear coupling of two collective modes of a condensed gas of rubidium atoms. Using a modified time averaged orbiting potential trap we changed the trap anisotropy to a value where the frequency of the m = 0 high-lying mode corresponds to twice the frequency of the m = 0 low-lying mode, thus leading to strong nonlinear coupling between these modes. By changing the anisotropy of the trap and exciting the low-lying mode we observed significant frequency shifts of this fundamental mode and also the generation of its second harmonic.

Abstract. We report an apparatus and method capable of producing Bose-Einstein condensates (BECs) of ∼ 1×106 87 Rb atoms, and ultimately designed for sympathetic cooling of 133 Cs and the creation of ultracold RbCs molecules. The method combines several elements: i) the large recapture of a magnetic quadrupole trap from a magneto-optical trap, ii) efficient forced RF evaporation in such a magnetic trap, iii) the gain in phase-space density obtained when loading the magnetically trapped atoms into a far red-detuned optical dipole trap and iv) efficient evaporation to BEC within the dipole trap. We demonstrate that the system is capable of sympathetically cooling the |F = 1, mF = −1 and |1, 0 sublevels with |1, +1 atoms. Finally we discuss the applicability of the method to sympathetic cooling of 133 Cs with 87 Rb.

We present measurements of interspecies thermalization between ultracold samples of 133 Cs and either 174 Yb or 170 Yb. The two species are trapped in a far-off-resonance optical dipole trap and 133 Cs is sympathetically cooled by Yb. We extract effective interspecies thermalization cross sections by fitting the thermalization measurements to a kinetic model, giving σ Cs 174 Yb = (5 ± 2) × 10 −13 cm 2 and σ Cs 170 Yb = (18 ± 8) × 10 −13 cm 2 . We perform quantum scattering calculations of the thermalization cross sections and optimize the CsYb interaction potential to reproduce the measurements. We predict scattering lengths for all isotopic combinations of Cs and Yb. We also demonstrate the independent production of 174 Yb and 133 Cs Bose-Einstein condensates using the same optical dipole trap, an important step towards the realization of a quantum-degenerate mixture of the two species.The realization of ultracold atomic mixtures [1][2][3][4][5][6][7][8][9][10][11][12] has opened up the possibility of exploring new regimes of few-and many-body physics. Such mixtures have been used to study Efimov physics [13][14][15], probe impurities in Bose gases [16], and entropically cool gases confined in an optical lattice [17]. Pairs of atoms in the mixtures can be combined using magnetically or optically tunable Feshbach resonances to create ultracold molecules [18][19][20][21][22][23][24][25][26]. These ultracold molecules have a wealth of applications, such as tests of fundamental physics [27][28][29], realization of novel phase transitions [30][31][32], and the study of ultracold chemistry [33,34]. In addition, the long-range dipole-dipole interactions present between pairs of polar molecules make them useful in the study of dipolar quantum matter [35,36] and ultracold molecules confined in an optical lattice can simulate a variety of condensedmatter systems [37][38][39].Although the large majority of work on ultracold molecules has focused on bi-alkali systems, there is burgeoning interest in pairing alkali-metal atoms with divalent atoms such as Yb [40][41][42][43][44][45] or Sr [46]. The heteronuclear 2 Σ molecules formed in these systems have both an electric and a magnetic dipole moment in the ground electronic state. The extra magnetic degree of freedom opens up new possibilities for simulating a range of Hamiltonians for spins interacting on a lattice and for topologically protected quantum information processing [47].One of the challenging aspects of creating molecules in these systems is that the Feshbach resonances tend to be narrow and sparse. They are narrow because the main coupling responsible for them is the weak distance dependence of the alkali-metal hyperfine coupling, caused by the spin-singlet atom at short range [48] [48,49], and for some systems may be at impractically high magnetic fields. Amongst the various alkali-Yb combinations, CsYb has been proposed as the most favorable candidate because the high mass of Cs facilitates a higher density of bound states near threshold and its large hyperfi...