Scattering by Entangled Spatial and Spin Degrees of Freedom

Abstract

Several recent experiments on liquid and solid samples containing protons or deuterons show an interesting anomaly, which is a shortfall in the intensity of energetic neutrons scattered by the samples. Previously we demonstrated that quantum correlations in the spatial and spin degrees of freedom of the hydrogen isotopes lead to entanglement in scattering and a reduction in the scattered intensity. The viability of short-lived quantum correlations as the cause of the observed anomalies is further explored and found to be entirely feasible. General features of the basic premiss, that quantum entanglement reduces the scattered signal, are discussed and the interpretation of the neutron scattering experiments is set in context to related work on other systems. For the experiments in question, the duration of a scattering event, τs, is a fraction of a femtosecond which is extremely short compared to solid-state relaxation times. Increasing τs, by suitably changing experimental conditions, restores the intensity to the standard value calculated from the single atom cross-section and concentration of particles. Our physical picture of the restoration is evolution with increasing τs from a pure state of the particles (described by a wavefunction) to a mixed state (described by a density matrix) that is created, through decoherence, by steadily engaging the solid-state environment of the particles.

Interpretation of the hydrogen anomaly in neutron and electron compton scattering

“…It is noted here that in contrast to earlier formulations [9,10] Eq. (12) does not contain any spindependence of the cross section (except for the one inherent in the exchange interaction).…”

“…The present interpretation of the hydrogen anomalies in Compton scattering is a further development of ideas presented in earlier publications [9,10], but with some essential modifications: (a) a deeper analysis of the temporal development of the neutron (or electron)-proton interactions during the scattering process and (b) a quantitative description of the coherence volume for the actual instrument used and of the probability for the scattering particle to interact coherently with two or more protons or deuterons. Furthermore, it has been found possible to interpret all data without introducing any spin-dependence of the neutron cross-section anomalies.…”

“…The mechanism for intensity loss considered here is the same as the one proposed earlier [9]: scattering on undistinguishable particles, in combination with large H-zero-point motion of the scatterers, reduces the scattering amplitude for H-pairs which fall within the coherence volume. The present treatment is extended to situations where more than two protons are interacting and includes also an explicit expression for the effect of decoherence on the scattering amplitudes.…”

“…The proposed explanations fall into two classes: In one of these (called non-BornOppenheimer), it is assumed that the recoil energy and momentum are shared between the proton and an electron in the eV range, which leads to intensity reduction at the normal position of the Compton peak [6,7]. The other class of theories is based on quantum entanglement between the protons, either caused by interaction with a common electronic field [3 (p 555), 8] during scattering or through the antisymmetrization rules valid for scattering on identical particles [9,10]. Destructive interference then leads to cross-section reductions.…”

Search for isotope effects in projectile and target ionization in swiftHe+onH2orD2Trinter1, Waitz2, Schöffler3 et al. 2014Phys. Rev. A2010View full textAdd to dashboardCite

“…All these results represent a challenge for conventional scattering theory as well as for molecular spectroscopy. No quantitative theory so far could explain all these anomalies, but all suggested approaches today contain quantum entanglement [6][7][8][9][10][11]. There is also criticism of the measurements by Cooper et al, see [12] and references therein.…”