Spin Polarization via Adiabatic and Counterdiabatic Engineering

A spin filter is a device that allows only a single spin state to pass, equivalent to a polarizing filter for a beam of light. Here, taking inspiration from shortcuts to adiabaticity, I demonstrate that the potential landscape of a typical quantum point contact can be tuned to act as a two terminal spin filter or to generate a spin-polarized beam. The effect presented is sufficiently robust that rough engineering yields a significant effect, as demonstrated by experiments on asymmetrically biased quantum point contacts in InAs quantum wells.