Proton-Proton Correlations in Condensed Matter

Abstract

Certain neutron scattering experiments indicate that protons pairs, or larger clusters, may stay quantum entangled in condensed matter for measurable times. This was first observed in Compton scattering of neutrons, a method which has a time-window of 10^-16 - 10^-15 s, but recent experiments with slow neutrons have given supporting evidence that isolated proton dimers in a crystalline material may stay quantum coherent for considerably longer times. Mechanisms leading to local proton entanglement are discussed briefly and a model for neutron scattering on correlated proton pairs is presented, which explains the observed decrease of cross-section as a result of destructive interferences for the particular case when a neutron scatters on two indistinguishable particles. The loss of interference, and the return of the cross-section to its normal value at longer times, is described by a quantitative decoherence model for the protons in water when perturbed by the fluctuating hydrogen bonds.