Efficient mapping for Anderson impurity problems with matrix product states

We propose an efficient algorithm to numerically solve Anderson impurity problems using matrix product states. By introducing a modified chain mapping we obtain significantly lower entanglement, as compared to all previous attempts, while keeping the short-range nature of the couplings. Employing a thermofield transformation, our approach naturally extends to finite temperatures, with applications to dynamical mean field theory, nonequilibrium dynamics, and quantum transport.