  We discuss a self-contained spin-boson model for a measurement-driven engine,
in which a demon generates work from thermal excitations of a quantum spin via
measurement and feedback control. Instead of granting it full direct access to
the spin state and to Landauer's erasure strokes for optimal performance, we
restrict this demon's action to pointer measurements, i.e. random or continuous
interrogations of a damped mechanical oscillator that assumes macroscopically
distinct positions depending on the spin state. The engine can reach
simultaneously the power and efficiency benchmarks and operate in temperature
regimes where quantum Otto engines would fail.
