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

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

#21
post #11
post #5

Earlier quoted context omitted.

Is the cost of cryocoolong capex or Opex dominated?

Are you referring to the hardware cost vs operating cost? Or how the units are financed?

capex = capital expenditure; opex = operational expenditure.

There's some theorem about investments that says it doesn't matter how they are financed. A good one is good, and a bad one is bad, whether or not you use debt.

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

#22

Earlier quoted context omitted.

>The 2.5 GHz prototype uses 80 times less energy than its semiconductor counterpart, even accounting for cooling It's in the header of the article.

The way it reads though is that the chip itself uses less power but still needs to be cooled which takes a lot of energy (traditionally)

>even accounting for cooling

No.

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

#25

: 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

Energy is expended when you zero or set a bit.

If you compute reversibly you need use special logic gates to not throw any bits away during the computation, like the Toffoli gate. All your operations need to have the same number of input and output bits and needs to be able to run forwards and backwards. Effectively you set or zero no bits during the entire computation that can't be losslessly reversed.

If you structure your computation this way you can do it adiabatically.

You still however need to expend energy when you set all the bits your program requires for execution when you start a computation.

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

#27

Earlier quoted context omitted.

If the superconducting microprocessor is 80x as efficient as a normal micro, that means that it uses about 100 million times as much energy as Landauer's principle. (A normal micro uses a billion times as much, and Landauer's energy is ~1/5th at superconducting temperature).

Yes, but the quote suggests no energy transfer at all. All you need then is a cold place (somewhere in remote space perhaps, or after the heat death of the Universe) and your computation can continue forever without power. It doesn't seem intuitive that that would be possible.

Continue forever? no. Be performed once at no cost? maybe.

I'm kinda sceptical that a computation to which the 2nd law is indifferent would occur spontaneously without immediately reversing. The 2nd law is what determines the direction that things typically progress.

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

#29

Earlier quoted context omitted.

The way it reads though is that the chip itself uses less power but still needs to be cooled which takes a lot of energy (traditionally)

>even accounting for cooling No.

stuff like this makes me wonder what the distribution on human context limits is.

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

#30

: 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

Energy is expended when you zero or set a bit. If you compute reversibly you need use special logic gates to not throw any bits away during the computation, like the Toffoli gate. All your operations need to have the same number of input and output bits and needs to be able to run forwards and backwards. Effectively you set or zero no bits during the entire computation that can't be losslessly reversed. If you struct…

I think maybe we need the idea of a "bit well" to match the "bit bucket".

Then it would be possible to just borrow bits when we set bits.

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