  By studying the time-dependent axial and radial growth of InSb nanowires, we
map the conditions for the synthesis of single-crystalline InSb nanocrosses by
molecular beam epitaxy. Low-temperature electrical measurements of InSb
nanocross devices with local gate control on individual terminals exhibit
quantized conductance and are used to probe the spatial distribution of the
conducting channels. Tuning to a situation where the nanocross junction is
connected by few-channel quantum point contacts in the connecting nanowire
terminals, we show that transport through the junction is ballistic except
close to pinch-off. Combined with a new concept for shadow-epitaxy of patterned
superconductors on nanocrosses, the structures reported here show promise for
the realization of non-trivial topological states in multi-terminal Josephson
Junctions.
