Photonic Maxwell's demon

Understand

We report an experimental realisation of Maxwell's demon in a photonic setup.

• We show that a measurement at the single-photon level followed by a feed-forward operation allows the extraction of work from intense thermal light into an electric circuit.
• The interpretation of the experiment stimulates the derivation of a new equality relating work extraction to information acquired by measurement.
• We derive a bound using this relation and show that it is in agreement with the experimental results.