Low-frequency critical current noise in Josephson junctions induced by temperature fluctuations

We demonstrate a spurious contribution to low-frequency critical current noise in Josephson junctions-normally attributed to charge trapping in the barrier-arising from temperature instabilities inherent in cryogenic systems. These temperature fluctuations modify the critical current via its temperature dependence. Cross-correlations between measured temperature and critical current noise in Al-AlOx-Al junctions show that, despite excellent temperature stability, temperature fluctuations induce observable critical current fluctuations. Particularly, because 1/f critical current noise has decreased with improved fabrication techniques in recent years, it is important to understand and eliminate this additional noise source.