Resonance interaction due to quantum coherence

TL;DR

This paper demonstrates that a steady resonance interaction energy exists between two atoms in a specific coherent superposition state, influenced by quantum coherence, and introduces a new measure called quantum classicality.

Contribution

It introduces the concept of quantum classicality and shows that resonance interaction depends on the quantum state of the two-atom system, with potential experimental tests using Rydberg atoms.

Findings

Resonance interaction exists in certain coherent superpositions.

Quantum classicality determines the presence of interaction.

Interaction can be tested with Rydberg atoms.

Abstract

The interaction energy between two atoms is crucially dependent on the quantum state of the two-atom system. In this paper, it is demonstrated that a steady resonance interaction energy between two atoms exists when the atoms are in a certain type of coherent superposition of single-excitation states. The interaction is tree-level classical in the sense of the Feynman diagrams. A quantity called quantum classicality is defined in the present paper, whose nonzero-ness ensures the existence of this interaction. The dependence of the interatomic interaction on the quantum nature of the state of the two-atom system may potentially be tested with Rydberg atoms.