  Josephson diodes are superconducting elements that show an asymmetry in the
critical current depending on the direction of the current. Here, we
theoretically explore how an alternating current bias can tune the response of
such a diode. We show that for slow driving there is always a regime where the
system can only carry zero-voltage dc current in one direction, thus
effectively behaving as an ideal Josephson diode. Under fast driving, the diode
efficiency is also tunable, although the ideal regime cannot be reached in this
case. We also investigate the residual dissipation due to the time-dependent
current bias and show that it remains small. All our conclusions are solely
based on the critical current asymmetry of the junction, and are thus
compatible with any Josephson diode.
