Yup. Originally it was cryotrons (not to be confused with krytrons),
which switched between normal and superconducting when a magnetic field
was applied. Dudley Buck and his collaborators got fairly far down that
road before his untimely death in 1959.
<
https://spectrum.ieee.org/dudley-bucks-forgotten-cryotron-computer>
(The writer doesn't know the difference between a cryotron and a
Josephson junction, which are about as alike as chalk and cheese, but
never mind.)
Then IBM spent many years and a whole bunch of money on trying to make
Josephson junction computers. Their first try was a Pb overlap junction
technology, which failed because iirc it wouldn't survive much
temperature cycling and was too slow anyway. Their second try (which a
couple of my pals worked on BITD) was based on niobium edge junctions,
which worked pretty well but never overcame the power and cost
disadvantages of a LHe technology.
<
http://www.w2agz.com/Library/Superconductivity/Anacker,%20IBM%20Josephson%20Project%20IBMJ.Res.Dev.24-2-107-112.pdf>
The program had been closed down well before I arrived in 1987, but I
heard lots of stories.
Cheers
Phil Hobbs
--
Dr Philip C D Hobbs
Principal Consultant
ElectroOptical Innovations LLC / Hobbs ElectroOptics
Optics, Electro-optics, Photonics, Analog Electronics
Briarcliff Manor NY 10510
http://electrooptical.net
http://hobbs-eo.com