Helium-3 and the Dilution Refrigerators That Cool Qubits
Superconducting and many other qubits run at millikelvin temperatures reached only with helium-3, a physical link between fusion byproducts and quantum hardware.
Why quantum hardware needs helium-3
Superconducting qubits, and several other leading modalities, operate at temperatures around 10-20 millikelvin. The only practical continuous cooling technology to reach that regime is the dilution refrigerator, which exploits the finite solubility of helium-3 in helium-4 near absolute zero. Cooling power comes from moving He-3 atoms across the phase boundary; without He-3 there is no dilution fridge.
# Dilution refrigerator cooling power (mixing chamber):
Q_dot ~= 84 * n_dot3 * T^2 [watts, SI-ish scaling form]
# n_dot3 = molar circulation rate of helium-3
# T = mixing-chamber temperature
# cooling power falls as T^2 -> He-3 circulation is the scarce lever
# below ~0.7 K, He-3 dissolving into superfluid He-4 provides coolingThe isotope, not the compute
This is a hardware-supply link, not a computational one. Terrestrial He-3 is scarce: it comes chiefly from tritium decay (tritium beta-decays to He-3 with a 12.3-year half-life). The breeder (Hyperion) is designed to produce a tritium-class product on the order of 4 kg/yr and, directly, on the order of 1.97 kg/yr of helium-3. That places Kronos on the supply side of the same isotope quantum computing depends on.
The demand context, honestly
- Each dilution fridge holds only a modest He-3 charge, but a scaling quantum sector means many thousands of fridges.
- Other He-3 demands (neutron detection, medical imaging, national security) already strain supply.
- He-3 is a genuinely constrained isotope; new primary production sources are strategically significant.
The connection to the burner is instructive and cuts the other way: the burner (Aegis / MetroVolt) would consume He-3 as fuel at roughly 400x domestic supply per commercial unit, one of the four honest burner gates, which is exactly why breeder-bred He-3 and, longer term, lunar He-3 matter. The overlap of these demands is the subject of the isotope-demand flywheel.