  The realization of a topological qubit calls for advanced techniques to
readily and reproducibly engineer induced superconductivity in semiconductor
nanowires. Here, we introduce an on-chip fabrication paradigm based on shadow
walls that offers substantial advances in device quality and reproducibility.
It allows for the implementation of novel quantum devices and ultimately
topological qubits while eliminating many fabrication steps such as lithography
and etching. This is critical to preserve the integrity and homogeneity of the
fragile hybrid interfaces. The approach simplifies the reproducible fabrication
of devices with a hard induced superconducting gap and ballistic
normal-/superconductor junctions. Large gate-tunable supercurrents and
high-order multiple Andreev reflections manifest the exceptional coherence of
the resulting nanowire Josephson junctions. Our approach enables, in
particular, the realization of 3-terminal devices, where zero-bias conductance
peaks emerge in a magnetic field concurrently at both boundaries of the
one-dimensional hybrids.
