Figure 1

The frequency dependent shear viscosity obtained from the QMC calculations for a ${10}^3$ lattice for two different temperatures: (upper panel) $T=0.16{\varepsilon }_F^{}$ (close to the critical temperature) and (lower panel) $T=0.30{\varepsilon }_F^{}$ (normal phase). The gray bands show uncertainty of the reconstruction. In the insets, the corresponding QMC correlators (blue points) are presented. The lines show the quality of the reproduction of the QMC data.Reuse & Permissions

Figure 2

The dimensionless static shear viscosity $\eta /n$ as a function of temperature for an $8^3$ lattice [solid (red) circles], a ${10}^3$ lattice [(blue) squares], and a ${12}^3$ lattice [(green) diamonds]. Vertical black dotted lines indicate the critical temperature of superfluid-to-normal phase transition for $T_c=0.15\left(1\right){\varepsilon }_F^{}$ and the onset of Cooper pair formation, $T^{*}\approx 0.22{\varepsilon }_F^{}$, respectively. The black line indicates smooth approximation of the QMC results and the (yellow) band reflects uncertainty of the viscosity computation. The (purple) asterisk shows the shear viscosity from the QMC calculations of Ref. [22]. The phonon contribution to the viscosity, evaluated according to Ref. [27] is shown as a dot-dashed (brown) line and it is accounted for in the (yellow) band. The hydrodynamic bound of Ref. [29] is plotted by the black dashed line. The inset shows the ratio of the shear viscosity to entropy density ($\eta /s$) as a function of $T/{\varepsilon }_F^{}$, obtained from the smooth approximation of the QMC results. The black dashed line indicates KSS bound: $1/4\pi$.Reuse & Permissions

Figure 3

The frequency dependent shear viscosity for the temperature $T=0.16{\varepsilon }_F^{}$ obtained by three different methodologies of the reconstruction as described in the text. The (purple) asterisk indicates the hydrodynamic bound obtained in Refs. [28, 29].Reuse & Permissions