  To design and construct hardware for general intelligence, we must consider
principles of both neuroscience and very-large-scale integration. For large
neural systems capable of general intelligence, the attributes of photonics for
communication and electronics for computation are complementary and
interdependent. Using light for communication enables high fan-out as well as
low-latency signaling across large systems with no traffic-dependent
bottlenecks. For computation, the inherent nonlinearities, high speed, and low
power consumption of Josephson circuits are conducive to complex neural
functions. Operation at 4\,K enables the use of single-photon detectors and
silicon light sources, two features that lead to efficiency and economical
scalability. Here I sketch a concept for optoelectronic hardware, beginning
with synaptic circuits, continuing through wafer-scale integration, and
extending to systems interconnected with fiber-optic white matter, potentially
at the scale of the human brain and beyond.
