Protecting quantum coherence of two-level atoms from vacuum fluctuations of electromagnetic field

TL;DR

This paper investigates how quantum coherence of two-level atoms is affected by vacuum electromagnetic fluctuations, showing that boundaries can help preserve coherence under specific conditions.

Contribution

It reveals the conditions under which quantum coherence can be protected from vacuum fluctuations, especially highlighting the role of boundaries and atomic polarizability.

Findings

Quantum coherence cannot be fully protected in non-boundary electromagnetic fields.

Boundaries can help preserve coherence when atoms are close and transversely polarizable.

Protection of coherence depends on atomic position and polarization direction.

Abstract

In the framework of open quantum systems, we study the dynamics of a static polarizable two-level atom interacting with a bath of fluctuating vacuum electromagnetic field and explore under which conditions the coherence of the open quantum system is unaffected by the environment totally. For both a single-qubit and two-qubit systems, we find that the quantum coherence can not be protected from noise when the atom interacts with a non-boundary electromagnetic field. However, with the presence of a boundary, the dynamical conditions for the insusceptible of quantum coherence are fulfilled only when the atom is close to the boundary and is transversely polarizable. Otherwise, the quantum coherence can only be protected in some degree in other polarizable direction.