2026-07-072026-07-07http://salesiana.dossiersoluciones.com/handle/123456789/92026We show that efficient quantum computation is possible using a disordered Heisenberg spin-chain with `always-on' couplings. Such disorder occurs naturally in nanofabricated systems. Considering a simple chain setup, we show that an arbitrary two-qubit gate can be implemented using just three relaxations of a controlled qubit, which amounts to switching the on-site energy terms at most twenty-one times.To appear in Phys. Rev. AQuantum PhysicsMaterials Sciencetext