Two-proton emission as source of spin-entangled proton pairs

TL;DR

This paper demonstrates that certain two-proton emitters can produce spin-entangled proton pairs with correlations exceeding classical bounds, especially when starting from a diproton-correlated initial state.

Contribution

It introduces a time-dependent three-body model showing how two-proton emission from a diproton-correlated state can generate spin-entangled pairs with measurable quantum correlations.

Findings

Emitted protons exhibit strong spin correlations surpassing local-hidden-variable bounds.

Sequential emission or absence of initial diproton correlation diminishes the spin-entanglement.

The initial diproton correlation is crucial for producing entangled proton pairs.

Abstract

We show that a two-proton emitter with a diproton-correlated initial state can act as a source of spin-correlated proton pairs. Using a time-dependent three-body model, we investigate the two-proton emission of $^{16}$Ne ($^{14}$O$+2p$) and analyze the spin correlation of the emitted protons. We find that, when the emission proceeds as a democratic three-body process from an initial state containing a spin-singlet diproton correlation, the emitted protons exhibit a pronounced spin-correlation pattern exceeding the local-hidden-variable bound. This spin correlation closely resembles that of a pure spin-singlet pair. In contrast, this pattern is lost when the process is dominated by the sequential emission or when the initial diproton correlation is absent. These results demonstrate that a certain class of two-proton emitters can deliver spin-entangled proton pairs, and their spin correlation reflects the diproton correlation embedded in the initial state.