Helium-3 Alternatives: Every Exit From the Shortage, Assessed

Table of ContentsThree Ways Out of a ShortageRoute One: Make More Helium-3Harvest the Tritium Already DecayingBreed Tritium on PurposeLet Fusion Feed ItselfSift It Out of Ordinary HeliumThe Russian WildcardThe Moon, BrieflyRoute Two: Need Less Helium-3Treat the Gas as Inventory, Not FuelThe One-Kelvin Escape HatchQubits That Run HotWhat the Last Shortage TeachesRoute Three: Replace the Millikelvin StageMagnetic Cooling: The State of PlayCooling From Inside the ChipDead Ends Worth NamingThe ScoreboardWhat I Would Do With This

In September 2011, the Government Accountability Office handed Congress a report with a bureaucratic title and a quietly triumphant conclusion. Three years earlier, the United States had burned through roughly 79,000 liters of helium-3 in a single year, most of it inside radiation portal monitors scanning cargo for smuggled nuclear material, and had nearly emptied its strategic reserve of the rarest stable gas on Earth. GAO-11-753 reported the way out: boron-10 lined proportional detectors had passed field testing and, in the GAO’s estimation, could be acquired and deployed with confidence. The world’s largest consumer of helium-3 did not find more helium-3. It redesigned the detector so it no longer needed the gas at all.

Fifteen years later, quantum computing is the demand spike, and the detector trick does not transfer. A dilution refrigerator uses helium-3 not for a convenient nuclear cross-section, which boron-10 could imitate, but for its quantum statistics: helium-3 is the only stable fermionic working fluid in cryogenics, and the phase-boundary physics that cools superconducting processors to 10 millikelvin has no substitute species, as I explained in my helium-3 explainer. So instead of one clean substitution, the industry is running every other play at once: harvesting more tritium, proposing to breed it deliberately, filtering helium-3 out of ordinary helium, moving qubits to warmer operating p…