How many particles make up a chaotic many-body quantum system?

TL;DR

This study numerically determines the minimum number of particles needed for strong chaos to appear in one-dimensional quantum systems, finding as few as 3 or 4 particles suffice regardless of system size.

Contribution

It reveals the minimal particle number required for quantum chaos onset in 1D systems with short- and long-range interactions, independent of system size.

Findings

Quantum chaos signatures appear with as few as 3-4 particles.

The onset of chaos does not depend on the overall system size.

Short-range and long-range interactions both exhibit minimal particle thresholds.

Abstract

We numerically investigate the minimum number of interacting particles, which is required for the onset of strong chaos in quantum systems on a one-dimensional lattice with short-range and long-range interactions. We consider multiple system sizes which are at least three times larger than the number of particles and find that robust signatures of quantum chaos emerge for as few as 4 particles in the case of short-range interactions and as few as 3 particles for long-range interactions, and without any apparent dependence on the size of the system.