# Emergent transport in a many-body open system driven by interacting quantum baths

## TL;DR

This paper investigates how interactions within quantum baths influence spin transport in an open many-body system, revealing phase transitions and emergent diffusive behavior through advanced simulations.

## Contribution

It demonstrates the emergence of diffusive phases and phase transitions driven by bath interactions in a non-homogeneous XXZ model using matrix-product-states simulations.

## Key findings

- Identification of ballistic, insulating, and diffusive phases depending on bath interaction strength.
- Observation of power-law decay in spin current during diffusive phase.
- Detection of a sharp change in oscillation frequency scaling at the phase diagram's triple point.

## Abstract

We analyze an open many-body system that is strongly coupled at its boundaries to interacting quantum baths. We show that the two-body interactions inside the baths induce emergent phenomena in the spin transport. The system and baths are modeled as independent spin chains resulting in a global non-homogeneous XXZ model. The evolution of the system-bath state is simulated using matrix-product-states methods. We present two phase transitions induced by bath interactions. For weak bath interactions we observe ballistic and insulating phases. However, for strong bath interactions a diffusive phase emerges with a distinct power-law decay of the time-dependent spin current $Q\propto t^{-\alpha}$. Furthermore, we investigate long-lasting current oscillations arising from the non-Markovian dynamics in the homogeneous case, and find a sharp change in their frequency scaling coinciding with the triple point of the phase diagram.