On the realization of a Q-state neuron

Q-state associative memories find use in color or gray scale image processing where each pixel can assume one of Q different intensities. In this paper, the authors present the realization of a Q-state neuron, for use in such memories, using a radio frequency driven superconducting Wheatstone bridge. The Q-states are obtained in the form of Shapiro steps observed in the transverse voltage of such bridges for large values of DC biasing currents. If low temperature semiconductors are used variable synapses can be realized using superconducting field effect transistors whose normal resistance and supercurrent vary with the applied gate voltage. Wheatstone bridges made of cuprate superconductors with synapses consisting of flux flow transistors or DC-SQUIDs could be used for neural chip operation at 77 K. Low power dissipation makes the proposed neuron implementation attractive for use in the fabrication of large scale neural circuits