  The long-standing paradigm of Maxwell's demon is till nowadays a frequently
investigated issue, which still provides interesting insights into basic
physical questions. Considering a single-electron transistor, where we
implement a Maxwell demon by a piecewise-constant feedback protocol, we
investigate quantum implications of the Maxwell demon. To this end, we harness
a dynamical coarse-graining method, which provides a convenient and accurate
description of the system dynamics even for high measurement rates. In doing
so, we are able to investigate the Maxwell demon in a quantum-Zeno regime
leading to transport blockade. We argue that there is a measurement rate
providing an optimal performance. Moreover, we find that besides building up a
chemical gradient, there can be also a regime where additionally the system
under consideration provides energy to the demon due to the quantum
measurement.
