# Single-Particle Entanglement Dynamics in Complex Systems

## TL;DR

This paper explores how single-particle entanglement entropy changes in complex systems based on system parameters, revealing a universal functional that governs these dynamics.

## Contribution

The paper introduces a universal functional that captures the dynamics of single-particle entanglement entropy in complex systems.

## Key findings

- A single functional of system parameters governs the entropy dynamics.
- The entropy is sensitive to collective information content rather than individual system details.
- The functional identifies universality classes and connections between quantum states.

## Abstract

We analyze the effect of varying system conditions on the single-particle entanglement entropy for an arbitrary eigenstate of a complex system that can be described by a multiparametric Gaussian ensemble. Our theoretical analysis leads to the identification of a single functional of the system parameters that governs the entropy dynamics. This reveals a sensitivity of the entropy to collective information content, characterized by the functional, instead of the individual system details. The functional can further be used to identify the universality classes as well as a deep web of connection underlying different quantum states.