Decoherence via coupling to a finite quantum heat bath

TL;DR

This paper investigates how decoherence occurs in a finite, isolated quantum system by modeling ultracold atoms in a double well potential coupled to a single atom, revealing that thermalization leads to accelerated decoherence.

Contribution

It demonstrates that thermalization in a finite quantum system causes accelerated decoherence, linking chaos and eigenstate structure to the decoherence process.

Findings

Thermalized ultracold atoms accelerate decoherence of the coupled atom.

Chaotic eigenstates emerge in the thermalized system.

Decoherence correlates with the onset of chaos in the environment.

Abstract

Decoherence of a quantum state coupled to an exterior environment is at the foundation of our understanding of the emergence of classical behavior from the quantum world, but how does it emerge in a finite closed quantum system? Here this is studied by modeling an isolated quantum system of a handful of ultracold atoms confined to a double well potential and coupled to a single atom of a different type. The ultracold atoms thermalize and serve as an environmental bath for the single atom. We observe accelerated decoherence of the single atom when ultracold atoms have thermalized. This is explained by the emergence of chaotic eigenstates in the thermalized system.