  We have studied low-frequency resistance fluctuations in shadow-evaporated
Al/AlOx/Al tunnel junctions. Between 300 K and 5 K the spectral density follows
a 1/f-law. Below 5 K, individual defects distort the 1/f-shape of the spectrum.
The spectral density decreases linearly with temperature between 150 K and 1 K
and saturates below 0.8 K. At 4.2 K, the spectral density is about two orders
of magnitude lower than expected from a recent survey [D. J. Van Harlingen et
al., Phys. Rev. B 70, 064510 (2004)]. Due to the saturation below 0.8 K the
estimated qubit dephasing times at 100 mK are only about two times longer than
calculated by Van Harlingen et al.
