Measuring the Evolution of Entanglement in Compton Scattering

TL;DR

This paper investigates how entanglement evolves during Compton scattering, showing it remains non-separable, behaves similarly to classical correlations, and does not require nonlocal explanations, supported by analytical results and experiments.

Contribution

It provides the first analytical link between entanglement measures and scattering states, demonstrating entanglement persistence and clarifying decoherence puzzles.

Findings

Entanglement measure equals concurrence after scattering.

States never become separable during the process.

Experimental results confirm theoretical predictions.

Abstract

The evolution of the entanglement measure during Compton scattering is studied. Our analytical results show that the corresponding measure coincides with the concurrence of the two-qubit state arising after scattering. The state never collapses to a separable one, contrary to what was previously assumed. The behavior of quantum entanglement during scattering is identical to the behavior of initially classically correlated photons up to a constant factor equal to two. This is consistent with local quantum field theory, and "spooky action at a distance" is not required to explain the change in state of nonlocally entangled qubits during the measurement of one of them. Our dedicated experiment with annihilation photons confirms these results and explains the "Puzzle of Decoherence" observed recently.