Shunt-Controlled Resistive State of Superconducting Wires

The use of resistive shunts in superconducting electronics is vast and versatile, to dampen oscillations in junctions, stabilize switching behavior, aid current sensing, divert current during quenches, and protect both the superconductor and the circuit from damage. In single-photon detection by superconducting nanowires, the shunt is crucial for the timely relaxation of the sensor between the events to detect. Here we step out from the superconducting state and discuss the effect of the shunt resistor on the resistive state of a superconducting wire, at elevated currents still below the critical current for the transition to the normal state. We reveal how the shunt resistance controls the system dynamics and the onset of different resistive phases that include hot-spot and phase-slippage events. The accompanying dynamic current redistribution in the circuit also affects the local heating properties and additionally contributes to the control of the resistive state, particularly important at the elevated operation temperatures.