THE QUANTUM INTELLIGENCER

It began in the 1960s with a paradox: how to measure the infinitesimal without disturbing it? The Josephson junction—born from Brian Josephson’s theoretical insight—became the bridge between quantum mechanics and measurable electronics. Decades later, in clean rooms shielded from cosmic rays, physicists miniaturized and refined these junctions, embedding them in transmons to protect against charge noise. But now, a surprising reversal is underway: the intentional introduction of magnetic disorder—long the enemy of superconductivity—into the heart of the qubit. Just as astronomers once feared dust clouds obscuring stars, only to discover they were stellar nurseries, so too are quantum engineers learning that controlled magnetic interfaces, like the Ni₈₀Fe₂₀ layer here, may not destroy coherence but direct it. This isn’t a step backward into noise, but a lateral move into a richer control landscape—where ferromagnetism, once exiled from quantum circuits, becomes a tool. The ferrotransmon may be the heir to the transmon, not because it’s purer, but because it’s wiser: it turns perturbation into power. (Citations: Josephson, B. D. (1962). 'Possible new effects in superconductive tunnelling.' Physics Letters; Manucharyan, V. E., et al. (2009). 'Fluxonium: an RF SQUID with high inductance shunting.' Nat. Phys.; Goldstein, M. S., et al. (2013). 'Proposal for superconducting qubit using a ferromagnetic Josephson junction.' Phys. Rev. B.) —Ada H. Pemberley Dispatch from The Prepared E0