That's true. But the sun's surface temperature is almost 6000 K. Radiative heat transfer is governed by some fairly demanding equations. At 6000 K, you can lose quite a lot of heat to the vacuum. At room temperature, the amount is a lot less (the amount radiated scales as the fourth power of absolute temperature).
Pulling one watt of thermal energy from quantum computing temperatures up to room temperature takes almost 3kW of power, with 100% mechanical efficiency. Actual practical cryocoolers are much less efficient than that, from 1 to 5%.
That means that it will take something on the order of 150kW of electrical power to remove one watt of thermal energy from a quantum computer.
Of course, that 150 kW has to be generated, stored, converted from one form to another, etc. That all generates more heat.
But, as I said, what do I know.
The cryocooler on the James Webb Space Telescope needs around 300 watts of power to lift 55 mW of heat from 6.2K to a hot side temperature of around 300 K, which is about 80° F.
Lifting the same amount of heat from 0.1 K would require much more power. And 0.1 K is the high limit for present day quantum computing circuitry.
But what do I know.
But what do I know.
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I have no idea what you know. But I’m willing to bet that the people who will invest tens of billions in something will make sure to employ scientists and engineers who do know their areas of expertise well. And those scientists/engineers would also be required to extensively test that knowledge and all equipment to ensure it’s scalable and durable in the intended environment.
“The cryocooler on the James Webb Space Telescope needs around 300 watts of power to lift 55 mW of heat from 6.2K to a hot side temperature of around 300 K, which is about 80° F.”
I see you did some reading but the above statement shows you didn’t understand what you read.
“At 6000 K, you can lose quite a lot of heat to the vacuum”
You can’t lose any heat to a vacuum.
“Pulling one watt of thermal energy from quantum computing temperatures up to room temperature takes almost 3kW of power, with 100% mechanical efficiency. Actual practical cryocoolers are much less efficient than that, from 1 to 5%.
That means that it will take something on the order of 150kW of electrical power to remove one watt of thermal energy from a quantum computer
But what do I know.”
You misunderstand. On the moon room temperature VERY VERY VERY VERY cold.
“Lifting the same amount of heat”
You don’t “lift” heat.
You transfer energy. Heat is a measure of the energy tranferred.
“That all generates more heat.”
Which is of no concern since it would be removed by passive cooling.
“Of course, that 150 kW has to be generated, stored, converted from one form to another, etc”
Set up a few solar cells up on the ridge.
“The cryocooler on the James Webb Space Telescope needs around 300 watts of power to lift 55 mW of heat from 6.2K to a hot side temperature of around 300 K, which is about 80° F.”
As before, that statement shows your misunderstanding of the material you just googled.
The JWST cryocooler does not raise the helium temperature to 300 K.
The JWST helium shroud uses passive cooling to bring temperatures downt to less than 40 K. Some sources say 32 K.
The cryocooler only has do work below 40 K.