On-chip laser-driven free-electron spin polarizer

Spin-polarized electron beam sources enable studies of spin-dependent electric and magnetic effects at the nanoscale. We propose a method of creating spin-polarized electrons on an integrated photonics chip by laser-driven nanophotonic fields. A two-stage interaction separated by a free-space drift length is proposed, where the first stage and drift length introduces spin-dependent characteristics into the probability distribution of the electron wave function. The second stage uses an adjusted optical near field to rotate the spin states utilizing the spin-dependent wave-packet distribution to produce electrons with high ensemble average spin expectation values. This platform provides an integrated and compact method to generate spin-polarized electrons, implementable with millimeter scale chips and tabletop lasers.