Spin-Textured Neutron Beams with Orbital Angular Momentum

Abstract

We present an experimental protocol that generates spin-textured neutron beams with definite states of orbital angular momentum (OAM) via birefringent neutron spin-polarization devices known as magnetic Wollaston prisms. Neutron OAM beams are mathematically characterized by a "corkscrew" phase singularity e i φ about the propagation axis where is the OAM quantum number. To understand the precise relationship between the emergent OAM state and the variety of spin textures realized by our setup, we have developed a path integral approach that in the interferometric limit makes a judicious use of magnetic Snell's law. Our formalism provides an intuitive and mathematically straightforward way of estimating both the transverse and longitudinal intrinsic coherence lengths of the neutron. We compare our approach to the well-known single-path Larmor precession model, and also discuss potential uses of such spin-textured beams.