186 research outputs found

    Degenerate quantum gases of strontium

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    Degenerate quantum gases of alkaline-earth-like elements open new opportunities in research areas ranging from molecular physics to the study of strongly correlated systems. These experiments exploit the rich electronic structure of these elements, which is markedly different from the one of other species for which quantum degeneracy has been attained. Specifically, alkaline-earth-like atoms, such as strontium, feature metastable triplet states, narrow intercombination lines, and a non-magnetic, closed-shell ground state. This review covers the creation of quantum degenerate gases of strontium and the first experiments performed with this new system. It focuses on laser-cooling and evaporation schemes, which enable the creation of Bose-Einstein condensates and degenerate Fermi gases of all strontium isotopes, and shows how they are used for the investigation of optical Feshbach resonances, the study of degenerate gases loaded into an optical lattice, as well as the coherent creation of Sr_2 molecules.Comment: Review paper, 43 pages, 24 figures, 249 reference

    Accessing Rydberg-dressed interactions using many-body Ramsey dynamics

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    We demonstrate that Ramsey spectroscopy can be used to observe Rydberg-dressed interactions. In contrast to many prior proposals, our scheme operates comfortably within experimentally measured lifetimes, and accesses a regime where quantum superpositions are crucial. The key idea is to build a spin-1/2 from one level that is Rydberg-dressed and another that is not. These levels may be hyperfine or long-lived electronic states. An Ising spin model governs the Ramsey dynamics, for which we derive an exact solution. Due to the structure of Rydberg interactions, the dynamics differs significantly from that in other spin systems. As one example, spin echo can increase the rate at which coherence decays. The results also apply to bare (undressed) Rydberg states as a special case, for which we quantitatively reproduce recent ultrafast experiments without fitting

    Promoting Queer Competency Through An Experiential Framework

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    Many counselors report feeling under prepared to effectively work with queer persons. Arguably, this can be mitigated through early intervention within training programs. However, many counseling programs do not adequately prepare their students to work with queer persons. To eliminate this gap in training, this article combines endorsed counseling competencies and experiential learning as an approach to enhance counselor queer training and preparation. This approach primarily framed through the Multicultural and Social Justice Counseling Competencies, and further supported through the Competencies for Counseling with LGBQQIA Individuals, and the ALGBTIC Competencies for Counseling with Transgender Clients can create an encompassing curricula and pedagogical framework for counselor educators

    Pumped quantum systems: immersion fluids of the future?

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    Quantum optical techniques may yield immersion fluids with high indices of refraction without absorption. We describe one such technique in which a probe field experiences a large index of refraction with amplification rather than absorption, and examine its practicality for an immersion lithography application. Enhanced index can be observed in a three-level system with a tunable, near-resonant, coherent probe and incoherent pump field that inverts population of the probe transition. This observation contradicts the common belief that large indices of refraction are impossible without absorption, however it is well in accord with existing electromagnetic theory and practice. Calculations show that a refractive index >> 2 is possible with practical experimental parameters. A scheme with an incoherent mixture of pumped and unpumped atoms is also examined, and is seen to have a lower refractive index (~2) accompanied by neither gain nor loss.Comment: 6 pages, 7 figures, accepted for publication in J. Vac. Sci. Tech. B, Nov/Dec 2005 (full reference not known yet

    Cool vibes

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    Cold Collision Frequency Shift of the 1S-2S Transition in Hydrogen

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    We have observed the cold collision frequency shift of the 1S-2S transition in trapped spin-polarized atomic hydrogen. We find Δν1S2S=3.8(8)×1010nHzcm3\Delta \nu_{1S-2S} = -3.8(8)\times 10^{-10} n Hz cm^3, where nn is the sample density. From this we derive the 1S-2S s-wave triplet scattering length, a1S2S=1.4(3)a_{1S-2S}=-1.4(3) nm, which is in fair agreement with a recent calculation. The shift provides a valuable probe of the distribution of densities in a trapped sample.Comment: Accepted for publication in PRL, 9 pages, 4 PostScript figures, ReVTeX. Updated connection of our measurement to theoretical wor

    1S-2S Spectrum of a Hydrogen Bose-Einstein Condensate

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    We calculate the two-photon 1S-2S spectrum of an atomic hydrogen Bose-Einstein condensate in the regime where the cold collision frequency shift dominates the lineshape. WKB and static phase approximations are made to find the intensities for transitions from the condensate to motional eigenstates for 2S atoms. The excited state wave functions are found using a mean field potential which includes the effects of collisions with condensate atoms. Results agree well with experimental data. This formalism can be used to find condensate spectra for a wide range of excitation schemes.Comment: 13 pages, 4 figure
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