  One of the most formidable challenges of scaling up quantum computers is that
of control signal delivery. Today's small-scale quantum computers typically
connect each qubit to one or more separate external signal sources. This
approach is not scalable due to the I/O limitations of the qubit chip,
necessitating the integration of control electronics. However, it is no small
feat to shrink control electronics into a small package that is compatible with
qubit chip fabrication and operation constraints without sacrificing
performance. This so-called "wiring challenge" is likely to impact the
development of more powerful quantum computers even in the near term. In this
paper, we address the wiring challenge of trapped-ion quantum computers. We
describe a control architecture called WISE (Wiring using Integrated Switching
Electronics), which significantly reduces the I/O requirements of ion trap
quantum computing chips without compromising performance. Our method relies on
judiciously integrating simple switching electronics into the ion trap chip -
in a way that is compatible with its fabrication and operation constraints -
while complex electronics remain external. To demonstrate its power, we
describe how the WISE architecture can be used to operate a fully connected
1000-qubit trapped ion quantum computer using ~ 200 signal sources at a speed
of ~ 40 - 2600 quantum gate layers per second.
