  Based on the investigation of the multi-terminal conductance of a system
composed of two graphene nanoribbons, in which one is on top of the other and
rotated by 60 degrees, we propose a setup for a 50/50 electronic beam splitter
that neither requires large magnetic fields nor ultra low temperatures. Our
findings are based on an atomistic tight-binding description of the system and
on the Green's function method to compute the Landauer conductance. We
demonstrate that this system acts as a perfect 50/50 electronic beam splitter,
in which its operation can be switched on and off by varying the doping (Fermi
energy). We show that this device is robust against thermal fluctuations and
long range disorder, as zigzag valley chiral states of the nanoribbons are
protected against backscattering. We suggest that the proposed device can be
applied as the fundamental element of the Hong-Ou-Mandel interferometer, as
well as a building block of many devices in electron optics.
