Dynamical correlation functions from complex time evolution

As quantum systems evolve in time, their entanglement usually grows quickly, making tensor network methods inefficient. ``Imaginary time'' evolution is efficient, but extrapolating back to the real axis is ill-conditioned. Here, the authors show that complex time, a mixture of the two, remains efficient while allowing a controlled reconstruction technique. Therefore, one can reach significantly longer times, which they demonstrate by obtaining high-accuracy results for impurity models at low energies.