  Recent proposals using heterostructures of superconducting and either
topologically insulating or semiconducting layers have been put forth as
possible platforms for topological quantum computation. These systems are
predicted to contain Ising anyons and share the feature of having only neutral
edge excitations. In this note, we show that these proposals can be combined
with the recently proposed "sack geometry" for implementation of a phase gate
in order to conduct robust universal quantum computation. In addition, we
propose a general method for adjusting edge tunneling rates in such systems,
which is necessary for the control of interferometric devices. The error rate
for the phase gate in neutral Ising systems is parametrically smaller than for
a similar geometry in which the edge modes carry charge: it goes as $T^3$
rather than $T$ at low temperatures. At zero temperature, the phase variance
becomes constant at long times rather than carrying a logarithmic divergence.
