  Although superconducting nanowire single-photon detectors (SNSPDs) are a
promising technology for quantum optics, metrology, and astronomy, they
currently lack a readout architecture that is scalable to the megapixel regime
and beyond. In this work, we have designed and demonstrated such an
architecture for SNSPDs, called the thermally-coupled imager (TCI). The TCI
uses a combination of time-of-flight delay lines and thermal coupling to create
a scalable architecture that can scale to large array sizes, allows neighboring
detectors to operate independently, and requires only four microwave readout
lines to operate no matter the size of the array. We give an overview of how
the architecture functions, and demonstrate a proof-of-concept $32\times32$
imaging array. The array was able to image a free-space focused spot at 373 nm,
count at 9.6 Mcps, and resolve photon location with greater than 99.83\%
distinguishability.
