Deuteron photo-decay with subsequent proton detection represents an experiment similar to Bohm’s version of the EPR arrangement replacing the entangled spin singlet state of the two-fermion system by entangled isospin states. Dropping the conception of truth, the detection as charge symmetry breaking event a posteriori leads up to a pre-existing proton identifying the second possibly far apart nucleon as neutron. That explains what the entangled isospin state predicts without assumption of a superluminal correlation.
Deuteron photo-decay with subsequent proton detection represents an experiment similar to Bohm’s version of the EPR arrangement replacing the entangled spin singlet state of the two-fermion system by entangled isospin states. Dropping the conception of truth, the detection as charge symmetry breaking event a posteriori leads up to a pre-existing proton identifying the second possibly far apart nucleon as neutron. That explains what the entangled isospin state predicts without assumption of a superluminal correlation.
It is pointed out that ordinary quantum mechanics as a phenomenological theory cannot account for the wave function collapse if it is not seen within the frame work of free field quantization which is needed to understand the particle structure of matter during wave packet evolution and to explain the collapse as symmetry breakdown by detection. Deuteron photo decay and the decay of a two-fermion spin singlet state (Bohm's version of EPR) with subsequent detection of one fermion serve as examples. A projection postulate and superluminal signals are not necessary to understand what entangled states predict.
Abstract Quantum entanglement in scattering processes has most often been treated in general terms only. A few examples of detailed calculations exist for atomic systems but for nuclear processes it is an almost unexplored area, although it may be important for interpretation of some measured quantities. The present treatment is a study of the time-development of the deuteron-like compound state created in the n – p scattering process. The increase and decay of neutron–proton entanglement in this state is calculated for low transferred momenta over the atto-second range. It is well known that the very high value for the bound proton cross sections ( σ = 81.9 barns) is caused by a specific feature in the deuteron, a virtual 0+ state close to its binding level. In scattering this state causes a negative phase shift δ s in the outgoing neutron wave function, increasing linearly with the transferred momentum. This phase shift is produced during a short-lived virtual energy transfer Δ E in exciting the 0+ state and Δ E is estimated here from the ratio of the phase shift δ observed and the time Δ t it takes to create the entanglement. It is further argued that the nuclear excitation decreases after the n – p encounter in proportion to the degree of n – p entanglement calculated, i.e. as long as the scattering state has deuteron characteristics. This phase shift is neglected in low energy neutron scattering text-books (which are based on the Fermi pseudo potential) and may be negligible for thermal neutron scattering, but will be important already at epithermal energies (0.1–1 eV). The phase shift has measurable consequences in interpretation of INS (inelastic neutron scattering) since its associated energy shift increases quadratically with the transferred momentum. It explains quantitatively certain anomalies found in scattering on water, where water vibration modes are excited far below the expected transferred momentum limit. This paper ends with a short discussion about quantum entanglement in scattering processes in general, with the present example as a starting point.
We investigate the spin entanglement in few-nucleon scattering processes involving nucleons and deuterons. For this purpose, we consider the entanglement power introduced by Beane et al. We analyze different entanglement entropies as a basis to define the entanglement power of the strong interaction and calculate the corresponding entanglement powers for proton-neutron, neutron-deuteron, proton-deuteron, and deuteron-deuteron scattering. For the latter two processes, we also take into account the modification from the Coulomb interaction. In contrast to proton-neutron scattering, no universal low-energy features are evident in the spin entanglement in neutron-deuteron, proton-deuteron, and deuteron-deuteron scattering.