Non-Markovian Open Quantum Systems Dynamics with Tree Tensor Network Methods

The simulation of large-scale dissipative quantum systems is a significant challenge arising in several areas of physics and chemistry. In this talk we will discuss PyTTN our recently developed software package for simulating dynamical properties of open quantum systems. This package that makes use of Tree Tensor Network state (or equivalently the multi-layer multiconfiguration time dependent Hartree) based representations of state vector, including the use of the multi-set ansatz that is best suited to problems where the bath dynamics depends strongly on the system configuration. The software has been designed with a focus on performance and ease of setup of new models and wavefunction topologies. We will demonstrate both unitary dynamics as well as non-unitary Hierarchical Equation of motion and pseudomode based approaches for the simulation to standard open quantum system models and more challenging models of exciton transport in organic materials.