Josephson Junction DAC

Currently being used in calibration standards and other spendy research shenanigans.

http://ieeexplore.ieee.org/Xplore/login.jsp?url=/iel4/5667/15175/00700136.pdf?arnumber=700136

Someone must be out there already, just waiting for the technology to get cheap enough to allow this to be used for an audio DAC. Probably best to wait till then to try to figure out how to convert PCM or DSD directly to the necessary RF signal.

It's impressive that JJ's have gotten sufficiently reproducible as to be practical (if one can live with the necessary cryogenics).

A dear friend did some "undergrad thesis" work at Reed College on JJ's. He said it was quite frustrating---one day they would work and another not. But that was a long time ago.

The stories about Brian Josephson's relatively early days are also quite amusing. I believe he was taking heavy-hitter Phil Anderson's solid-state physics course, and Anderson said he would come up to him after a lecture to tell him how he should have explained the material, and in some cases where he had made mistakes.

Most hard-physics types think he "went off the deep end" in later life as he began to study metaphysics/spirituality. I'd like to know what he thinks now :green:

EDIT: He's still going strong evidently at the age of 67, see: http://www.google.com/search?hl=en&q=%22Brian+Josephson%22&btnG=Search

I was reading an HP paper the other night about the lengths they went to to verify the performance of their recent DMMs and they state that there has been a JJ based voltage standard in use in HP's standards lab since late 1988. almost 20 years ago.

http://www.agilent.com/metrology/pdf/msc1989_3458a.pdf

Yeah the cool thing is that JJs link voltage standards directly to frequency standards.