Emulating a quantum Maxwell's demon with non-separable structured light

TL;DR

This paper demonstrates a classical light-based emulation of a quantum Maxwell's demon using non-separable structured light, confirming entropy exchange and enabling work extraction, thus providing a scalable platform for studying information thermodynamics.

Contribution

It introduces a classical vectorial light setup to emulate a quantum Maxwell's demon, simplifying experimental challenges and enabling scalable studies of information-driven thermodynamics.

Findings

Entropy increases in the demon while decreasing in the system, conserving total entropy.

The demon extracts orbital angular momentum as useful work.

Structured light can emulate quantum thermodynamic processes.

Abstract

Maxwell's demon (MD) has proven an instructive vehicle by which to explore the relationship between information theory and thermodynamics, fueling the possibility of information driven machines. A long standing debate has been the concern of entropy violation, now resolved by the introduction of a quantum MD, but this theoretical suggestion has proven experimentally challenging. Here, we use classical vectorially structured light that is non-separable in spin and orbital angular momentum to emulate a quantum MD experiment. Our classically entangled light fields have all the salient properties necessary of their quantum counterparts but without the experimental complexity of controlling quantum entangled states. We use our experiment to show that the demon's entropy increases during the process while the system's entropy decreases, so that the total entropy is conserved through an exchange of information, confirming the theoretical prediction. We show that our MD is able to extract useful work from the system in the form of orbital angular momentum, opening a path to information driven optical spanners for the mechanical rotation of objects with light. Our synthetic dimensions of angular momentum can easily be extrapolated to other degrees of freedom, for scalable and robust implementations of MDs at both the classical and quantum realms, enlightening the role of a structured light MD and its capability to control and measure information.