Probing picosecond depairing currents in type-II superconductors

https://www.nature.com/articles/s41567-026-03469-z

Comments

oliculipoliculaSep 25, 2026, 11:50 PM
"Insiders" (ahem why does OP think this is interesting ) chip in on the following and others? They could also be standard, but I an likely much more wrong about how interesting they are?

1) frequency upconverted light with BBO generates photocurrents (But it doesn't seem like the measurement itself is "quantum-enhanced"? As I understand it the process generates entangled photon pairs?)

2)etching gold with very mild chemicals (KI would be a health supplement after your nuclear apocalypse. YBCO in your cup of phosphoric acid doesn't seem so bad either)

3) https://www.colorado.edu/conference/bss/media/4149

hakken306Sep 26, 2026, 10:50 PM
Found a much more readable summary for people who aren't already physics grad students, but have some minor knowledge of superconductors.

https://www.cui-advanced.uni-hamburg.de/en/research/wissensc...

adrian_bSep 27, 2026, 7:06 AM
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.

pixelpoetSep 26, 2026, 10:16 PM
I use mathematical jargon all the time, but I gotta admit, getting major Turbo Encabulator[0] vibes here :D

[0] https://www.youtube.com/watch?v=Ac7G7xOG2Ag

orbital-decaySep 26, 2026, 10:50 PM
Electrons in superconductors form Cooper pairs that are theoretically predicted to break (depair) at a certain current. However it's hard to observe because the other effects break superconductivity before you reach that current. They managed to circumvent this by sending the current in picosecond pulses, which is the novel part, and confirm the prediction. They did it for two types of superconductors with different mechanisms of action: classic low-temperature superconductors and modern high-temperature (YBCO).