Short-lived ‘Schrödinger’s cat’ states of protons in metal–hydrogen systems: a new effect

Abstract

Recent neutron Compton scattering (NCS) investigations on niobium and palladium hydrides at ambient temperatures are reviewed. These experiments were motivated by (i) our previous theoretical work on short-lived quantum entanglement (QE) of protons in condensed matter, and (ii) our first experimental verification of this new effect with NCS from liquid H 2O/D 2O mixtures. All these NCS experiments revealed a striking anomalous behaviour of the total neutron scattering cross-section densities of protons, in the sub-femtosecond time scale. Whereas at small scattering angles the ratio of the cross-section of protons with respect to that of the metals corresponded to conventional theory, an ‘anomalous’ decrease was observed for increasing angles. Based on the fundamental van Hove theory, a first-principles theoretical interpretation of this novel effect is presented which takes explicitly into account QE of protonic states and its decoherence.