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Shunt-controlled resistive state of superconducting wires

Khalil Harrabi, Zain Alzoubi, Leonardo Cadorim, Milorad Milosevic

Abstract

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.

Shunt-controlled resistive state of superconducting wires

Abstract

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.
Paper Structure (5 sections, 4 equations, 3 figures)

This paper contains 5 sections, 4 equations, 3 figures.

Table of Contents

  1. Introduction
  2. Experimental Setup
  3. Theoretical Formalism
  4. Results and Discussion
  5. Conclusion

Figures (3)

  • Figure 1: Experimental setup and measured resistance of a shunted superconducting wire. (a) Schematic depiction of the sample and the measurement setup, showing a lateral voltage probe for the superconducting wire shunted by a resistor. The sample is current biased, using a pulse generator, a series of calibrated attenuators, and a delay line essential for isolating the incident pulse from the reflected pulse, all connected via 50 $\Omega$ coaxial cables. (b) The current-voltage characteristics of a superconducting stripe (width 10$\mu$m, $T=9$K) in the resistive state, for different shunt resistances. Two stages are visible in the resistive state for all shunts used, with a negative differential resistance transition between them.
  • Figure 2: Simulated I-V curves and visualization of the resistive states. (a) I-V curves as calculated from TDGL for different values of the shunt resistance. Panel (b) is a zoom on the panel (a), for better visibility of the transitions in the resistive state. The representative snapshots 1-4 of the selected dynamic states are shown below as the plots of the condensate density.
  • Figure 3: Temporal characterization of the resistive states. Voltage and supercurrent versus time, corresponding to state $2$ from Fig. \ref{['fig2']} (applied current density $J=1.06J_{GL}$), for two values of the shunt resistance: $R_s=0.5R_{GL}$ (a,b) and $R_s=10R_{GL}$ (c,d). The observed temporal features and characteristic times are in direct correlation with condensate dynamics shown through selected snapshots on the right.