Xiaojun Yao, IQuS, University of Washington

Relativistic hydrodynamics has been used to study collective behavior of light particles produced in heavy ion collisions. It has been shown that hydrodynamic calculations with a small shear viscosity give results that agree well with experimental data. Furthermore, a holographic calculation showed that the ratio of shear viscosity and entropy density is as small as 1/(4 pi) for strongly coupled N=4 supersymmetric Yang-Mills theory, which is consistent with the value extracted from experimental data via hydrodynamic simulations. On the other hand, calculating shear viscosity in QCD is very challenging: Perturbative calculations are not applicable in the temperature range of interest and Euclidean lattice QCD calculations have uncontrolled systematic uncertainties caused by the ill-defined spectral reconstruction problem. In this talk, I will discuss the Hamiltonian lattice approach that enables real-time calculations. I will take the 2+1D SU(2) pure gauge theory as an example and show some preliminary results obtained on a small lattice. The calculations take into account the running coupling and find the ratio of shear viscosity and entropy density is consistent with 1/(4 pi). Finally, I will discuss a quantum algorithm to calculate the shear viscosity, which may help us to perform calculations on larger lattices and achieve the physical limit.