Neutron Compton scattering by proton and deuteron systems with entangled spatial and spin degrees of freedom - art. no. 062714

Several recent experiments on liquid and solid samples containing protons o r deuterons have shown an interesting anomaly, which is apparently absent w hen the hydrogen isotopes are replaced by heavier particles. The anomaly is a shortfall in the intensity of energetic neutrons scattered by the sample s; specifically, the intensity per hydrogen isotope in bulk samples is smal ler than the intensity for total scattering by an isolated hydrogen isotope . Short-lived correlations in the spatial and spin degrees of freedom of th e hydrogen isotopes have been proposed as an explanation of the anomaly. Th e correlations involve entanglements of the degrees of freedom created by t he requirements of quantum mechanics applied to identical particles. By usi ng energetic neutrons to perform Compton scattering experiments on the hydr ogen isotopes, the time scale of the experimental probe covers the region o f 10(-16)-10(-15) s where entangled states might still be expected to survi ve. The proposed explanation is pursued here by reporting the cross section for Compton scattering, also known as deep inelastic scattering, by two id entical nuclei occupying nonequivalent states. The model reproduces the obs erved dependence of the cross section on energy transfer, in which intensit y accumulates at the recoil energy of a single nucleus. Several features of the model demand that the intensity at the recoil energy is indeed less th an the intensity for total scattering by an isolated nucleus. Although the pair approximation used here is unquestionably a first approximation to rea l many-body entanglements, it is a compelling explanation of all the observ ations, including the restoration of the normal cross section at longer obs ervation times achieved by moving to longer scattering times.