Superconducting Microprocessors? Turns Out They're Ultra-Efficient (2021)

: The research group in Japan sought to create a superconductor microprocessor that’s adiabatic, meaning that, in principle, energy is not gained or lost from the system during the computing process.

I thought that there was a law of information theory that requires expending energy, I think it's Landauer's principle. It seems to be disputed though.

https://en.wikipedia.org/wiki/Landauer%27s_principle

Interesting. To give some context to the current problem: the classical (CMOS) logic gates energy is expended to charge or discharge the load capacitance of each electrical node during a state change. Charging a capacitor to a certain voltage requires E=CV^2 amount of (Joules) energy (C in Farads, V in volts). From this, half of it is the energy stored at the capacitor, other half is the energy converted to heat on the transistors. This is so far the most efficient way we can build large scale integrated logic, and at best it is 50% efficient. In reality there is also unwanted inefficiencies, making it close to 30% or so. Good to keep in mind: 100% of the energy becomes heat because the charged capacitor needs to be discharged at some point to change its state. This is becoming a huge thermal management nightmare.

4 bit CPU, about 10,000 gates, 5 GHz. So just a proof of concept at this point.

Cyrogenic computing has been too far outside the mainstream. The mainstream technology improved faster than the cyrogenic stuff.

NSA put large amounts of money into cyrogenic computing, from the 1960s on. "I want a thousand-megacycle computer. I'll get you the money!" - an NSA director. It never really worked out, although at one point some special purpose device, probably a key tester, was actually built. The first round of that cyrogenic technology used cyrotrons. Cyrotrons were fast, but, being magnetic devices, not small enough. The second round used Josephson junctions. NSA finally gave up on that around the time ordinary CMOS passed 1GHz. Lately there's been some interest again.[1]

[1] https://spectrum.ieee.org/will-the-nsa-finally-build-its-sup...

Pardon my ignorance, but would this then be a semisuperconductor or a supersemiconductor?

A more recent take on this subject:

https://diginomica.com/superconducting-chips-could-pack-data...

Great, I can make my software even more shitty, and nobody will notice.

According to the paper, their demonstration chip MANA has 21k of JJ units, which according to their estimates correspond to around 5k transistors. To compare, a single Nvidia GA100 has 54 * 10^9 transistors.

This is the future. As we try to go 3D and start stacking dies, the limiting factor of heat is getting even more blocking.

It's not about consuming less electricity. It's about dissipating less of it as heat inside the microprocessor. The future will made of tiny porous cubes that are tall sandwiches of RAM and CPU/GPU/etc

I worked on a team (at a Company) that built a Scanning SQUID Microscope (SSM) to image magnetic flux trapping in superconducting circuits. The organization that bought the SSM is working on these kinds superconducting microprocessors. A SSM uses a SQUID (superconducting quantum inference device) as an extremely sensitive magnetic flux sensor; SQUID sensor requires further amplification which is also typically a SQUID-based low-noise amplifier (long story). Same Company (I worked for) built cryostats for quantum computing research and all kinds of other cryogenic needs.

There are a lot of issues with designing, fabricating, operating these sort of circuits at large scale... hence the need for a microscope to study flux trapping and other phenomena of operating circuits. But, overall, I'm optimistic that this technology can work.

A note about energy consumption of this technology. Niobium thin film superconducting circuits have to be cooled to about 4 Kelvin to be 'properly 'operational'. Heat leaks from higher temperature stages into the 4 Kelvin cooling zone via conduction of thermal insulating supports, electrical signal lines, and thermal blackbody radiation. Several kW of power are required to provide 1 Watt of cooling power at 4 Kelvin.

There are also small resistive/impedance losses in electrical signal lines connecting room temperature electronics to the superconducting chip. So... I think calling the microprocessor 'adiabatic' is a little disingenuous. Small amounts of power, in the form of many nano-amp and micro-amp currents are required to operate and interface with the chip... the chip cannot operate without this electrical interface.

In additional, in a test environment where researchers are only running one chip... the overall cryogenic system, electronics, and superconducting chip are wildly energy inefficient compared to current microprocessors. But the "forward looking statement" is that hundreds of microprocessors could be run in one cryostat and the 5kW cooling budget would replace the power draw of 100's of classical microprocessors while also provide higher equivalent FLOPS per process processor. But this "forward looking statement" is NOT true today, as far as I am aware.

This will be incredible when the cooling at consumer-level has been figured out. I do wonder what kind of material requirements/availability there will be though. Even things like touchscreens and other rare earth metals are either getting scarce or controlled by one or two countries.

Regardless, exciting news here for all of us

How much energy was needed for the cryostat? I haven't found anything on that in the article.

Relevant video about some of the history of superconducting computers: https://www.youtube.com/watch?v=14r2oMsAaE8

I'm surprised that this wasn't done earlier. An experiment like this seemed like an obvious useful thing to try the first time I heard about superconductors, some decades ago.

Perhaps it is due to the technical difficulty of the experiment.

Is there any company trying to bring this to market?

Another notch on the belt for a cryocooler boom.

Oh “superconducting is hard”, “if only we had high temperature superconductors”. All valid, but if we work with what we got and disrupt cyrocoolers make them a commodity like magnetrons all those laments become moot.

Prove me wrong.

To quote Norm MacDonald:

... according to a report in the medical journal "DUH"

unfortunately the title says 'superconducting' when it should say 'reversible'