Superconducting circuits and methods for detecting a rising edge of an input signal are described. An example superconducting circuit includes an input terminal for receiving an input signal comprising both positive pulses and negative pulses. The superconducting circuit further includes a first stage, coupled to the input terminal and a first node, configured to suppress both any backward propagating negative pulses and any forward propagating negative pulses, and allow propagation of any forward propagating positive pulses. The superconducting circuit further includes a second stage, coupled to the first node, configured to store a forward propagating positive pulse and reflect a stored positive pulse back to the first node as a negative pulse such that in response to each rising edge of the input signal a return-to-zero signal comprising both a rising edge and a falling edge is provided as an output at the first node.