  In this work, we demonstrate that making a cut (a narrow vacuum regime) in
the bulk of a quantum anomalous Hall insulator (QAHI) creates a topologically
protected single helical channel with counter-propagating electron modes, and
inducing superconductivity on the helical channel through proximity effect will
create Majorana zero energy modes (MZMs) at the ends of the cut. In this
geometry, there is no need for the proximity gap to overcome the bulk
insulating gap of the QAHI to create MZMs as in the two-dimensional
QAHI/superconductor (QAHI/SC) heterostructures. Therefore, the topological
regime with MZMs is greatly enlarged. Furthermore, due to the presence of a
single helical channel, the generation of low energy in-gap bound states caused
by multiple conducting channels is avoided such that the MZMs can be well
separated from other in-gap excitations in energy. This simple but practical
approach allows the creation of a large number of MZMs in devices with
complicated geometry such as hexons for measurement-based topological quantum
computation. We further demonstrate how braiding of MZMs can be performed by
controlling the coupling strength between the counter-propagating electron
modes.
