  The development of superconducting electronics based on nanocryotrons has
been limited so far to few-device circuits, in part due to the lack of standard
and robust logic cells. Here, we introduce and experimentally demonstrate
designs for a set of nanocryotron-based building blocks that can be configured
and combined to implement memory and logic functions. The devices were
fabricated by patterning a single superconducting layer of niobium nitride and
measured in liquid helium on a wide range of operating points. The tests show
$10^{-4}$ bit error rates with above $20\,\%$ margins up to $50\,$MHz and the
possibility of operating under the effect of a perpendicular $36\,$mT magnetic
field, with $30\,\%$ margins at $10\,$MHz. Additionally, we designed and
measured an equivalent delay flip-flop made of two memory cells to show the
possibility of combining multiple building blocks to make larger circuits.
These blocks may constitute a solid foundation for the development of
nanocryotron logic circuits and finite-state machines with potential
applications in the integrated processing and control of superconducting
nanowire single-photon detectors.
