We carry out an extensive numerical study of low-temperature electronic transport in
quantum point contacts based on twisted bilayer graphene. Assuming ballistic electron
dynamics, quantized plateaus in the conductance are observed in defect-free samples when
the twisting angle is large enough. However, plateaus are smeared out and hardly
noticeable on decreasing the angle. Close to the magic angle, the conductance around the
charge neutrality point drops significantly and the quantization steps visible at higher angles …

Quantum point contacts (QPC), short one-dimensional conductors that can be
electrostatically defined or etched in two-dimensional materials, are the center of attention
for their prospective applications in spin, valley and charge nanodevices. Although
fabrication by etching generally produces defects and roughness which hinder the
properties of the pristine materia, recent cryoetching techniques overcome these problems
and have demonstrated the fabrication of low-defect graphene QPCs via etching processes …