  One of the most primitive but elusive current-voltage (I-V) responses of a
superconductor is when its supercurrent grows steadily after a voltage is first
applied. The present work employed a measurement system that could
simultaneously track and correlate I(t) and V(t) with sub-nanosecond timing
accuracy, resulting in the first clear time-domain measurement of this
transient phase where the quantum system displays a Newtonian like response.
The technique opens doors for the controlled investigation of other time
dependent transport phenomena in condensed-matter systems.
