Half-Mirror for Electrons in Quantum Hall Copropagating Edge Channels in a Mach-Zehnder Interferometer

A half-mirror that divides a spin-polarized electron into two parallel copropagating spin-resolved quan-tum Hall edge channels one half each is presented in this study. The partition process is coherent, as confirmed by observing the Aharonov-Bohm oscillation at high visibility of up to 85% in a Mach-Zehnder interferometer, which comprises two such half-mirrors. The coherence length of the interferometer exceeds 200 mu m, which reflects the robust nature of the copropagating channels against the decoher-ence caused by the coupling to the environment. In addition, the device characteristics are highly stable, making the device promising in the application of quantum information processing. The beam-splitting process is theoretically modeled, 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.