The important practical achievement that enabled these measurements is that they have fabricated some custom photoconductive switches, which can generate extremely short electrical pulses, of a few picoseconds, when receiving laser pulses.
The technology to generate ultrashort laser pulses is rather old, but it is difficult to generate electrical pulses at a similar time scale.
They have also made a custom amplifier for the signals measured from the superconductor.
Photoconductive switches function in the same way as a classic photoresistor, but they are designed in such a way to enable switching times that are many orders of magnitude lower and they are biased with voltages high enough to cause avalanche multiplication of the mobile charge carriers generated by the incoming laser pulse.
The technology to generate ultrashort laser pulses is rather old, but it is difficult to generate electrical pulses at a similar time scale.
They have also made a custom amplifier for the signals measured from the superconductor.
Photoconductive switches function in the same way as a classic photoresistor, but they are designed in such a way to enable switching times that are many orders of magnitude lower and they are biased with voltages high enough to cause avalanche multiplication of the mobile charge carriers generated by the incoming laser pulse.