Self-Evaporation Dynamics of Quantum Droplets in a 41K-87Rb Mixture

We theoretically investigate the self-evaporation dynamics of quantum droplets in a 41K-87Rb mixture, in free-space. The dynamical formation of the droplet and the effects related to the presence of three-body losses are analyzed by means of numerical simulations. We identify a regime of parameters allowing for the observation of the droplet self-evaporation in a feasible experimental setup.This work was supported by the Spanish Ministry of Science, Innovation and Universities and the European Regional Development Fund FEDER through Grant No. PGC2018-101355-B-I00 (MCIU/AEI/FEDER, UE), by the Basque Government through Grant No. IT986-16

Λ{\Lambda}-enhanced grey molasses on the D2D_2 transition of Rubidium-87 atoms

Laser cooling based on dark states, i.e. states decoupled from light, has proven to be effective to increase the phase-space density of cold trapped atoms. Dark-states cooling requires open atomic transitions, in contrast to the ordinary laser cooling used for example in magneto-optical traps (MOTs), which operate on closed atomic transitions. For alkali atoms, dark-states cooling is therefore commonly operated on the $D_1$ transition $n S_{1/2}\rightarrow n P_{1/2}$. We show that, for $^{87}\text{Rb}$, thanks to the large hyperfine structure separations the use of this transition is not strictly necessary and that $"$quasi-dark state$"$ cooling is efficient also on the $D_2$ line, $5 S_{1/2}\rightarrow 5 P_{3/2}$. We report temperatures as low as $(4.0\pm 0.3)\,\mu$K and an increase of almost an order of magnitude in the phase space density with respect to ordinary laser sub-Doppler cooling

A Bose-Einstein condensate in an optical lattice with tunable spacing: transport and static properties

In this Letter we report the investigation of transport and static properties of a Bose-Einstein condensate in a large-spaced optical lattice. The lattice spacing can be easily tuned starting from few micrometers by adjusting the relative angle of two partially reflective mirrors. We have performed in-situ imaging of the atoms trapped in the potential wells of a 20 micrometers-spaced lattice. For a lattice spacing of 10 micrometers we have studied the transport properties of the system and the interference pattern after expansion, evidencing quite different results with respect to the physics of BECs in ordinary near-infrared standing wave lattices, owing to the different length and energy scales.Comment: 11 pages, 7 figures, revised version (modified figures, extended text

Scientifico! like Dad: On the Intergenerational Transmission of STEM Education in Italy

We provide novel evidence on the existence and the extent of intergenerational transmission of STEM (Science, Technology, Engineering and Mathematics) education using a recent large administrative dataset of Italian graduates obtained from the Almalaurea data. Parental influence on two STEM educational outcomes (high school and university degree completion) is strong and, net of student's time-invariant unobserved heterogeneity, proves to be stronger at the stage of the educational career closer to labour market entry. At this stage, the influence of fathers outweighs the one of mothers and is larger for sons than for daughters. The documented STEM intergenerational transmission is not driven by liberal profession of parents for most of STEM fields, while it is for some non-STEM fields (economic and legal studies), consistently with the presence of entry barriers in some professions

Quasiparticle dynamics in a Bose insulator probed by inter-band Bragg spectroscopy

We investigate experimentally and theoretically the dynamical properties of a Mott insulator in decoupled one-dimensional chains. Using a theoretical analysis of the Bragg excitation scheme we show that the spectrum of inter-band transitions holds information on the single-particle Green's function of the insulator. In particular the existence of particle-hole coherence due to quantum fluctuations in the Mott state is clearly seen in the Bragg spectra and quantified. Finally we propose a scheme to directly measure the full, momentum resolved spectral function as obtained in angle-resolved photoemission spectroscopy of solids.Comment: The new version contains improved theoretical treatment and data analysi

A Dual-Species Bose-Einstein Condensate with Attractive Interspecies Interactions

We report on the production of a 41 K- 87 Rb dual-species Bose\u2013Einstein condensate with tunable interspecies interaction and we study the mixture in the attractive regime; i.e., for negative values of the interspecies scattering length a 12 . The binary condensate is prepared in the ground state and confined in a pure optical trap. We exploit Feshbach resonances for tuning the value of a 12 . After compensating the gravitational sag between the two species with a magnetic field gradient, we drive the mixture into the attractive regime. We let the system evolve both in free space and in an optical waveguide. In both geometries, for strong attractive interactions, we observe the formation of self-bound states, recognizable as quantum droplets. Our findings prove that robust, long-lived droplet states can be realized in attractive two-species mixtures, despite the two atomic components possibly experiencing different potentials

Multimode Trapped Interferometer with Ideal Bose-Einstein Condensates

We experimentally demonstrate a multi-mode interferometer comprising a Bose-Einstein condensate of $^{39}$K atoms trapped in a harmonic potential, where the interatomic interaction can be cancelled exploiting Feshbach resonances. Kapitza-Dirac diffraction from an optical lattice coherently splits the BEC in multiple momentum components equally spaced that form different interferometric paths, closed by the trapping harmonic potential. We investigate two different interferometric schemes, where the recombination pulse is applied after a full or half oscillation in the confining potential. We find that the relative amplitudes of the momentum components at the interferometer output are sensitive to external forces, through the induced displacement of the harmonic potential with respect to the optical lattice. We show how to calibrate the interferometer, fully characterize its output and discuss perspective improvements.Comment: 7 pages, 6 figure