  We present results of high-cadence monitoring of the optical light curve of
the nearby, Type Ia SN 2014J in M82 using the 2.3m Aristarchos telescope. $B$
and $V$-band photometry on days 15-18 after $t_{max}(B)$, obtained with a
cadence of 2 min per band, reveals evidence for rapid variability at the
0.02-0.05 mag level on timescales of 15-60 min on all four nights, taking the
red noise estimation at face value. The decline slope was measured to be
steeper in the $B$-band than in $V$-band, and to steadily decrease in both
bands from 0.15 mag/day (night 1) to 0.04 mag/day (night 4) in V and from 0.19
mag/day (night 1) to 0.06 mag/day (night 4) in B, corresponding to the onset of
the secondary maximum. We propose that rapid variability could be due to one or
a combination of the following scenarios: the clumpiness of the ejecta, their
interaction with circumstellar material, the asymmetry of the explosion, or the
mechanism causing the secondary maximum in the near-infrared light curve. We
encourage the community to undertake high-cadence monitoring of future, nearby
and bright supernovae to investigate the intraday behavior of their light
curves.

Solar and Stellar Astrophysics;Cosmology and Nongalactic Astrophysics