810 research outputs found

    Precision measurement of gravity with cold atoms in an optical lattice and comparison with a classical gravimeter

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    We report on a high precision measurement of gravitational acceleration using ultracold strontium atoms trapped in a vertical optical lattice. Using amplitude modulation of the lattice intensity, an uncertainty Δg/g107\Delta g /g \approx 10^{-7} was reached by measuring at the 5th^{th} harmonic of the Bloch oscillation frequency. After a careful analysis of systematic effects, the value obtained with this microscopic quantum system is consistent with the one we measured with a classical absolute gravimeter at the same location. This result is of relevance for the recent interpretation of related experiments as tests of gravitational redshift and opens the way to new tests of gravity at micrometer scale.Comment: 4 pages, 4 figure

    Coherent control of quantum transport: modulation-enhanced phase detection and band spectroscopy

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    Amplitude modulation of a tilted optical lattice can be used to steer the quantum transport of matter wave packets in a very flexible way. This allows the experimental study of the phase sensitivity in a multimode interferometer based on delocalization-enhanced Bloch oscillations and to probe the band structure modified by a constant force.Comment: 8 pages, 3 figures, Submitted to EPJ Special Topics for the special issue on "Novel Quantum Phases and Mesoscopic Physics in Quantum Gases

    Test of Einstein Equivalence Principle for 0-spin and half-integer-spin atoms: Search for spin-gravity coupling effects

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    We report on a conceptually new test of the equivalence principle performed by measuring the acceleration in Earth's gravity field of two isotopes of strontium atoms, namely, the bosonic 88^{88}Sr isotope which has no spin vs the fermionic 87^{87}Sr isotope which has a half-integer spin. The effect of gravity upon the two atomic species has been probed by means of a precision differential measurement of the Bloch frequency for the two atomic matter waves in a vertical optical lattice. We obtain the values η=(0.2±1.6)×107\eta = (0.2\pm 1.6)\times10^{-7} for the E\"otv\"os parameter and k=(0.5±1.1)×107k=(0.5\pm1.1)\times10^{-7} for the coupling between nuclear spin and gravity. This is the first reported experimental test of the equivalence principle for bosonic and fermionic particles and opens a new way to the search for the predicted spin-gravity coupling effects.Comment: 5 pages, 4 figures. New spin-gravtity coupling analysis on the data added to the manuscrip

    High-precision spectroscopy of ultracold molecules in an optical lattice

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    The study of ultracold molecules tightly trapped in an optical lattice can expand the frontier of precision measurement and spectroscopy, and provide a deeper insight into molecular and fundamental physics. Here we create, probe, and image microkelvin 88^{88}Sr2_2 molecules in a lattice, and demonstrate precise measurements of molecular parameters as well as coherent control of molecular quantum states using optical fields. We discuss the sensitivity of the system to dimensional effects, a new bound-to-continuum spectroscopy technique for highly accurate binding energy measurements, and prospects for new physics with this rich experimental system.Comment: 12 pages, 4 figure

    Humerus shaft fracture complicated by radial nerve palsy: Is surgical exploration necessary?

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    Fractures of the humerus shaft often are complicated by radial nerve palsy. Controversy still exists in the treatment that includes clinical observation and eventually late surgical exploration or early surgical exploration. Algorithms have been proposed to provide recommendations with regard to management of the injuries. However, advantages and disadvantages are associated with each of these algorithms. The aim of this study was to analyze the indications of each treatment options and facilitate the surgeon in choosing the conduct for each lesion, proposing our own algorithm

    BaH molecular spectroscopy with relevance to laser cooling

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    We describe a simple experimental apparatus for laser ablation of barium monohydride (BaH) molecules and the study of their rovibrational spectra that are relevant to direct laser cooling. We present a detailed analysis of the properties of ablation plumes that can improve the understanding of surface ablation and deposition technologies. A range of absorption spectroscopy and collisional thermalization regimes has been studied. We directly measured the Franck-Condon factor of the B2Σ+(v=0)X2Σ+(v"=1)\mathrm{B}^2\Sigma^+(v'=0)\leftarrow\mathrm{X}^2\Sigma^+(v"=1) transition. Prospects for production of a high luminosity cryogenic BaH beam are outlined. This molecule is a promising candidate for laser cooling and ultracold fragmentation, both of which are precursors to novel experiments in many-body physics and precision measurement.Comment: 11 pages, 10 figure

    Technology applications in shoulder replacement

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    The advancement of technologies in orthopaedic surgery should provide the surgeon with precise and trustworthy support for pre-operative planning, intra-operative guidance and post-operative follow-up. The request for greater accuracy, predictable results and fewer complications, is the engine of digital evolution in pre-operative planning and computer-assisted surgery (CAS). It is an evolution rather than a revolution, and in the last few years these developments have begun to involve shoulder replacement surgery, too

    Oncoplastic conservative surgery for breast cancer: long-term outcomes of our first ten years experience

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    The main goal of oncoplastic breast surgery (OBS) is to optimize cosmetic outcomes and reduce patient morbidity, while still providing an oncologically-safe surgical outcome and extending the target population of conservative surgery. Although the growing number of reported experiences with oncoplastic surgery, few studies account for the long-term outcomes

    Optical frequency standard with ultra-cold strontium atoms

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