2026-07-072026-07-07http://salesiana.dossiersoluciones.com/handle/123456789/141955We present a simple microscopic model to show how fluctuating two--level systems in the Josephson junction tunnel barrier of thickness $L$ can modify the potential energy of the barrier and produce critical current noise spectra. We find low frequency $1/f$ noise that goes as $L^5$. Our values are in good agreement with recent experimental measurements of critical current noise in Al/AlO$_{x}$/Al Josephson junctions. We also investigate the sensitivity of the noise on the nonuniformity of the tunnel barrier.4 pages, 3 figuresSuperconductivityMesoscale and Nanoscale Physicstext