356 research outputs found

    Long-range nature of Feshbach molecules in Bose-Einstein condensates

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    We discuss the long-range nature of the molecules produced in recent experiments on molecular Bose-Einstein condensation. The properties of these molecules depend on the full two-body Hamiltonian and not just on the states of the system in the absence of interchannel couplings. The very long-range nature of the state is crucial to the efficiency of production in the experiments. Our many-body treatment of the gas accounts for the full binary physics and describes properly how these molecular condensates can be directly probed

    Collisions of cold magnesium atoms in a weak laser field

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    We use quantum scattering methods to calculate the light-induced collisional loss of laser-cooled and trapped magnesium atoms for detunings up to 30 atomic linewidths to the red of the 1S_0-1P_1 cooling transition. Magnesium has no hyperfine structure to complicate the theoretical studies. We evaluate both the radiative and nonradiative mechanisms of trap loss. The radiative escape mechanism via allowed 1Sigma_u excitation is dominant for more than about one atomic linewidth detuning. Molecular vibrational structure due to photoassociative transitions to bound states begins to appear beyond about ten linewidths detuning.Comment: 4 pages with 3 embedded figure

    Do patients with type 2 diabetes who aren't taking insulin benefit from self-monitoring blood glucose?

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    Patients with type 2 diabetes who aren't on insulin and perform self-monitoring of blood glucose (SMBG) show small but significant reductions in hemoglobin A1c (HbA1c) at 6 months but not at 12 months (strength of recommendation [SOR]: B, systematic reviews and meta-analyses of disease-oriented evidence). Patients with a baseline HbA1c 8% do (SOR: B, systematic reviews and meta-analyses of disease-oriented evidence). More frequent SMBG--4 to 7 times weekly--doesn't reduce HbA1c more than less frequent self-monitoring--1 or 2 times a week (SOR: B, a systematic review and meta-analysis of disease-oriented evidence)

    Quantum and Semiclassical Calculations of Cold Atom Collisions in Light Fields

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    We derive and apply an optical Bloch equation (OBE) model for describing collisions of ground and excited laser cooled alkali atoms in the presence of near-resonant light. Typically these collisions lead to loss of atoms from traps. We compare the results obtained with a quantum mechanical complex potential treatment, semiclassical Landau-Zener models with decay, and a quantum time-dependent Monte-Carlo wave packet (MCWP) calculation. We formulate the OBE method in both adiabatic and diabatic representations. We calculate the laser intensity dependence of collision probabilities and find that the adiabatic OBE results agree quantitatively with those of the MCWP calculation, and qualitatively with the semiclassical Landau-Zener model with delayed decay, but that the complex potential method or the traditional Landau-Zener model fail in the saturation limit.Comment: 21 pages, RevTex, 7 eps figures embedded using psfig, see also http://www.physics.helsinki.fi/~kasuomin
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