Publications (39) View all
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Article: The temperature evolution of the shear viscosity in a Unitary Fermi Gas
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ABSTRACT: We present an ab initio determination of the shear viscosity for the unitary Fermi gas based on finite temperature quantum Monte Carlo calculations and the Kubo linear-response formalism. The results are confronted with the bound for the shear viscosity originating from hydrodynamic fluctuations. Assuming smoothness of the frequency dependent shear viscosity eta(omega), we show that the bound is violated in the low temperature regime and the violation occurs simultaneously with the onset of the Cooper paring in the system. In order to preserve the hydrodynamic bound in QMC eta(omega) has to possess a sharp structure located in the vicinity of zero frequency which is not resolved by an analytic continuation procedure.04/2013; -
Article: Cooper pairing above the critical temperature in a unitary fermi gas.
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ABSTRACT: We present an ab initio determination of the spin response of the unitary Fermi gas. Based on finite temperature quantum Monte Carlo calculations and the Kubo linear-response formalism, we determine the temperature dependence of the spin susceptibility and the spin conductivity. We show that both quantities exhibit suppression above the critical temperature of the superfluid-to-normal phase transition due to Cooper pairing. The spin diffusion transport coefficient does not display a minimum in the vicinity of the critical temperature and drops to very low values D_{s}≈0.8ℏ/m in the superfluid phase. All these spin observables show a smooth and monotonic behavior with temperature when crossing the critical temperature T_{c}, until the Fermi liquid regime is attained at the temperature T^{*}, above which the pseudogap regime disappears.Physical Review Letters 03/2013; 110(9):090401. · 7.37 Impact Factor -
Article: Shear viscosity of a unitary fermi gas.
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ABSTRACT: We present an ab initio determination of the shear viscosity η of the unitary Fermi gas, based on finite temperature quantum Monte Carlo calculations and the Kubo linear-response formalism. We determine the temperature dependence of the shear viscosity-to-entropy density ratio η/s. The minimum of η/s appears to be located above the critical temperature for the superfluid-to-normal phase transition with the most probable value being (η/s)_{min}≈0.2ℏ/k_{B}, which is close the Kovtun-Son-Starinets universal value ℏ/(4πk_{B}).Physical Review Letters 07/2012; 109(2):020406. · 7.37 Impact Factor -
Article: Isovector giant dipole resonance from the 3D time-dependent density functional theory for superfluid nuclei
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ABSTRACT: A fully symmetry unrestricted time-dependent density functional theory extended to include pairing correlations is used to calculate properties of the isovector giant dipole resonances of the deformed open-shell nuclei 172Yb (axially deformed), 188Os (triaxially deformed), and 238U (axially deformed) and to demonstrate good agreement with experimental data on nuclear photo-absorption cross sections for two different Skyrme force parametrizations of the energy density functionals SkP and SLy4.Physical Review C 11/2011; 84(5):051309(R). · 3.31 Impact Factor -
Article: The Equation of State of the Unitary Fermi Gas: An Update on Lattice Calculations
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ABSTRACT: The thermodynamic properties of the unitary Fermi gas (UFG) have recently been measured to unprecedented accuracy at the MIT. In particular, these measurements provide an improved understanding of the regime below T/eF ~ 0.20, where a transition into a superfluid phase occurs. In light of this development, we present an overview of state-of-the-art auxiliary field quantum Monte Carlo (AFQMC) results for the UFG at finite temperature and compare them with the MIT data for the energy, chemical potential, and density. These AFQMC results have been obtained using methods based on the hybrid Monte Carlo (HMC) algorithm, which was first introduced within the context of lattice QCD.11/2011;
