  In any general cycle of measurement, feedback and erasure, the measurement
will reduce the entropy of the system when information about the state is
obtained, while erasure, according to Landauer's principle, is accompanied by a
corresponding increase in entropy due to the compression of logical and
physical phase space. The total process can in principle be fully reversible. A
measurement error reduces the information obtained and the entropy decrease in
the system. The erasure still gives the same increase in entropy and the total
process is irreversible. Another consequence of measurement error is that a bad
feedback is applied, which further increases the entropy production if the
proper protocol adapted to the expected error rate is not applied. We consider
the effect of measurement error on a realistic single-electron box Szilard
engine. We find the optimal protocol for the cycle as a function of the desired
power $P$ and error $\epsilon$, as well as the existence of a maximal power
$P^{\max}$.
