Nuclear spin decoherence fundamentally limits quantum coherence times T2* in solid- state topological quantum devices. All leading Majorana platforms — InSb nanowires (In- 115, I=9/2; Sb-121, I=5/2), InAs nanowires (In-115, I=9/2; As-75, I=3/2), and proposed Bi-209 chains (I=9/2, 100%) — suffer from large, irreducible nuclear spin baths. We show that isotopically enriched Pb-208 (I=0) atomic chains confined in Silicalite-1 (pure-silica MFI zeolite) eliminate nuclear spin noise from both the chain atoms and the crystalline host framework. Computed T2* improves by 45x (natural Pb) to 669x (99.9% Pb-208) over Bi-209. The coherence advantage is parameter-independent — it follows from nuclear physics, not material modeling. Using the BHZ model adapted for zeolite confinement, we predict that Pb chains in MFI are topological (Z2=1, M/(2t)=0.92), with intrinsic superconductivity (Tc=7.1 K) and Kitaev-criterion topological gaps of 1.2-1.5 meV when combined with magnetic partners. We identify the Silicalite-1 framework as essential for avoiding Al-27 framework nuclear spins and present a complete decoherence budget for the platform.
Bradley John Hart (Sat,) studied this question.