Seminarium Optyczne

When an electron or photon propagates in a cylindrically symmetricwaveguide, its spin angular momentum (SAM) and its orbital angularmomentum (OAM) interact. Remarkably, we find that the dynamics resultingfrom this spin-orbit interaction are quantitatively described by a singleexpression applying to both electrons and photons. This leads to theprediction of several rotational effects: the spatial or time evolution ofeither particle's spin/polarization vector is controlled by the sign ofits OAM quantum number, or conversely, its spatial wave function iscontrolled by its SAM. We show that the common origin of these effects inelectrons and photons is a universal geometric phase, which implies thatthey occur for any particle with spin and thereby exist independently ofwhether or not the particle has mass, charge, or magnetic moment. Wedescribe current experimental progress towards characterizing thesephenomena for photons propagating in optical fibers, and demonstrate howthey can be used to reversibly transfer entanglement between the SAM andOAM degrees of freedom of two-particle states.