[YakBizzarro]

The claim that traditional electronics can't work at deep cryogenic temperatures is vastly exaggerated. Of course you can't take something as complex as a modern microprocessor and hope it works at 4K, but modern fully-depleted MOSFETs typically works. Their electrical characteristic will be different, so a tailored design it's often needed

[generuso]

Exactly. In physics, when people measured things at 4K, there were many examples of active circuits built to measure or amplify things in situ at 4K, and only send the results out, often by the same wire that was used to power the circuit.