Entangled protons in a solid polymer

In condensed matter systems, adjacent nuclei and their nearby electrons can all, in principle, be in a state of quantum entanglement, but the decoherence time would be exceedingly short—in the subfemtosecond realm. Still, the effect could be observable, according to Aris Chatzidimitriou-Dreismann (Technical University Berlin), because the time scale is roughly the same as the interaction time for Compton scattering. Several years ago, he performed neutron Compton scattering off water molecules and saw an anomalous shortfall of scattering from protons, which he attributed to short-lived nuclear entanglement. Now, he and his collaborators have Compton-scattered both neutrons and electrons off protons in a polymer called formvar. The electron experiments, done at the Australian National University in Canberra, showed precisely the same shortfall as the neutron experiments, done at the ISIS neutron spallation source in the UK. The similarity of the results is striking because the two projectiles interact with protons via fundamentally different forces—electromagnetic and strong. (C. A. Chatzidimitriou-Dreismann et al., Phys. Rev. Lett. 91 , 057403, 2003 http://dx.doi.org/10.1103/PhysRevLett.91.057403 .)