Interaction-Free Effects Between Distant Atoms

TL;DR

This paper explores how distant atoms can become entangled and exhibit nonlocal effects without exchanging photons, using quantum measurement schemes, Bell's theorem, and weak measurements, revealing novel interaction-free quantum phenomena.

Contribution

It introduces a quantum-mechanical scenario where entanglement and nonlocal effects occur without photon exchange, extending interaction-free measurement concepts.

Findings

Entanglement can be established without photon exchange.

Distant atoms can exhibit nonlocal correlations in an interaction-free manner.

Repeated interactions lead to the Quantum Zeno effect without photon exchange.

Abstract

A Gedanken experiment is presented where an excited and a ground-state atom are positioned such that, within the former's half-life time, they exchange a photon with 50% probability. A measurement of their energy state will therefore indicate in 50% of the cases that no photon was exchanged. Yet other measurements would reveal that, by the mere possibility of exchange, the two atoms have become entangled. Consequently, the "no exchange" result, apparently precluding entanglement, is non-locally established between the atoms by this very entanglement. This quantum-mechanical version of the ancient Liar Paradox can be realized with already existing transmission schemes, with the addition of Bell's theorem applied to the no-exchange cases. Under appropriate probabilities, the initially-excited atom, still excited, can be entangled with additional atoms time and again, or alternatively, exert multipartite nonlocal correlations in an interaction free manner. When densely repeated several times, this result also gives rise to the Quantum Zeno effect, again exerted between distant atoms without photon exchange. We discuss these experiments as variants of Interaction-Free-Measurement, now generalized for both spatial and temporal uncertainties. We next employ weak measurements for elucidating the paradox. Interpretational issues are discussed in the conclusion, and a resolution is offered within the Two-State Vector Formalism and its new Heisenberg framework.