Solving the transient Dyson equation with quasilinear complexity via matrix compression

We introduce a numerical strategy to efficiently solve the out of equilibrium Dyson equation in the transient regime. By discretizing the equation into a compact matrix form and applying state of the art matrix compression techniques, we achieve significant improvements in computational efficiency which results in quasilinear scaling of both time and space complexity with propagation time. This enables us to compute accurate solutions even for systems with multiple and disparate timescales. We benchmark our solver by simulating a voltage-biased Josephson junction formed by a quantum dot connected to two superconducting leads.