Dynamics and quantum entanglement of two-level atoms in de Sitter spacetime

TL;DR

This paper investigates how two-level atoms in de Sitter spacetime experience thermalization and entanglement decay, revealing the spacetime's intrinsic thermal nature and potential for experimental simulation.

Contribution

It demonstrates the thermalization of atomic states and entanglement decay due to de Sitter spacetime effects, providing insights into quantum field behavior in curved spacetime.

Findings

Atoms reach thermal equilibrium regardless of initial states.

Entanglement between atoms undergoes sudden death.

Thermalization and disentanglement can be simulated experimentally.

Abstract

In the framework of open quantum systems, we study the internal dynamics of both freely falling and static two-level atoms interacting with quantized conformally coupled massless scalar field in de Sitter spacetime. We find that the atomic transition rates depend on both the nature of de Sitter spacetime and the motion of atoms, interestingly the steady states for both cases are always driven to being purely thermal, regardless of the atomic initial states. This thermalization phenomenon is structurally similar to what happens to an elementary quantum system immersed in a thermal field, and thus reveals the thermal nature of de Sitter spacetime. Besides, we find that the thermal baths will drive the entanglement shared by the freely falling atom (the static atom) and its auxiliary partner, a same two-level atom which is isolated from external fields, to being sudden death, and the proper time for the entanglement to be extinguished is computed. We also analyze that such thermalization and disentanglement phenomena, in principle, could be understood from the perspective of table-top simulation experiment.