Spin - Orbital Angular Momentum Entanglement with Neutrons

It has been long known that Orbital Angular Momentum (OAM) of bound massive particles and free photons is quantized. However, in recent years stable OAM has also been observed in free massive particles, namely electrons. Even more recently it was demonstrated that OAM states can be prepared in free thermal neutrons using a spiral phase plate. This type of OAM is characterized as extrinsic OAM, which refers to the fact that each neutron in the beam has the same OAM with respect to the optical axis of the beam, but has a different intrinsic OAM, that is to say OAM with respect to their respective momentum vector. Thus new methods for generating OAM in neutrons were developed theoretically. It is predicted that a magnetic quadrupole can be used to create neutron OAM, entangled to the neutron spin (spin-orbit states). In addition to this existing theoretically method, we propose to apply static homogeneous electric field to generate OAM. Field polarization along the direction of particle propagation induces longitudinal spin orbit states, while a transversely polarized electric field generates transverse spin orbit states. Transversal OAM, induced by static electric fields, has not yet been observed in massive free particles. To sum up, the aim of the project is to prepare and identify longitudinal and transversal entangled spin orbit states with neutrons.