Quantum Control of Current Partition at Trifurcating Topological Channels

Topological channels can emerge a network along the domain walls that separate AB and BA stacking regions in minimally twisted bilayer graphene, which have been imaged by using scanning tunneling microscope recently. Here, we design a six-terminal graphene device to study how the incoming valley-polarized current will partition at the topological crossing point. We find that the incoming current not only can be partitioned into the two adjacent topological channels, but also goes straight along the incoming topological channel, which together form a trifurcating beam splitter. We provide a further systematic study on how to externally tune the trifurcating current partition by means of manipulating the system size, Fermi-energy, magnetic field, relative masses.