[volt-nuts] Low-cost Josephson Junction Array

Attila Kinali attila at kinali.ch
Wed Oct 19 19:56:40 EDT 2016

On Wed, 19 Oct 2016 12:15:56 -0700
Ken Peek <ken.peek at diligentminds.com> wrote:

> Well, I already have a 3458A, a 34420A, a GPSDO (with 10Mhz output), and so
> all I need is something that produces a fixed 10V (and 1V would be OK too).
> I was thinking of something like the "Compact Josephson Junction Array"
> [CJJA] that is used for inter-comparisons, etc.  This unit has an SIS
> array, and is very "finicky" to get working-- so something based on a SINIS
> array (highly damped) or something similar that can be used without having
> a PhD...
> It is already understood that NIST has the best solution for this if you
> want the "Cadillac" version, (and have virtually unlimited funds)-- but I
> don't have unlimited funds, and I don't need a programmable output, and I
> don't need to generate AC waveform, and I don't need or want all of the
> complexity.  $400K is *WAY* out of my budget.  I was looking more for
> something on the surplus market-- or some "cast away" JJA that someone is
> getting ready to throw into the dumpster-- something that nobody wants
> anymore that I can get working on a _very_limited_ budget...  That's why I
> mentioned the CJJA, because that has the RF source and everything built-in
> (well, except for the programmable current source, but I can build those
> all day long in my sleep).

Uhmm.. you are aware that any Josephson junction based system requires
cryogenic temperatures. Even the "high temperature" JJA still need liquid
helium, which is, as other have said, nothing that you can just buy.
Even the gear you need to keep liquid helium costs several 10k at least
on the surplus market... if you can get your hands on that stuff anyways
(that's lab equipment and lab equipment is usually used until it breaks
and cannot be repaired anymore). Even the microwave gear will cost
you at least a couple of thousand. If you want to get an idea how much
gear you need to run a JJA, have a look at page 30 of [1].

But don't worry, none of these systems need a PhD to use. Even though
the theory behind them is quite complicated and involves some heavy
math and physics, their use is pretty straight forward (at least for
a quantum physical system).

			Attila Kinali

[1] http://www.wmi.badw.de/teaching/Lecturenotes/AS/AS2013_Chapter6_Slides.pdf

Malek's Law:
        Any simple idea will be worded in the most complicated way.

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