Existing superconducting quantum computers need to be cooled near absolute zero. For example, some of D-Wave's machines are cooled to about $20 \ \mathrm {mK}$. Their design uses a dilution refrigerator.

Are there any other cooling methods for superconducting quantum computers besides dilution refrigerators which are capable of achieving such low temperatures?

Are there any specific commercial quantum computer designs or research projects using these other cooling methods?

  • $\begingroup$ "You must have 50 reputation to comment". Does anyone know how to add a "bounty" on this un-answered question about D-Wave? $\endgroup$ – user5115 Nov 15 '18 at 19:23
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    $\begingroup$ You will need at least 50 reputation for a bounty: stackoverflow.com/help/bounty $\endgroup$ – user820789 Nov 15 '18 at 19:30
  • $\begingroup$ As far as I know there are no practical alternatives to pulse tube dilution refrigerators. There are very few physical processes that avoid cooling power converging to zero as T -> 0. $\endgroup$ – psitae Nov 21 '18 at 22:15