  A half-mirror that divides a spin-polarized electron into two parallel
copropagating spin-resolved quantum Hall edge channels one half each is
presented in this study. The partition process was coherent, as confirmed by
observing the Aharonov-Bohm oscillation at a high visibility of up to 60% in a
Mach-Zehnder interferometer, which comprised two such half-mirrors. The device
characteristics were highly stable, making the device promising in the
application of quantum information processing. The beam-splitting process is
theoretically modelled, and the numerical simulation successfully reproduces
the experimental observation. The partition of the electron accompanied by the
spin rotation is explained by the angular momentum transfer from the orbital to
the spin via spin-orbit interactions.
