  In this work, a novel method for using a set of electromagnetic quadrupole
fields is presented to implement arbitrary unitary operators on a two-state
quantum system of electrons. In addition to analytical derivations of the
required quadrupole and beam settings which allow an easy direct
implementation, numerical simulations of realistic scenarios show the
feasibility of the proposed setup. This is expected to pave the way not only
for new measurement schemes in electron microscopy and related fields but even
one day for the implementation of quantum computing in the electron microscope.
