Bit-driven active matter: measurement turns noise into motive power

Active matter is material driven out of equilibrium at small scales by internal dissipation. Typically, this driving takes the form of a mechanical force exerted by constituents. What are the consequences when local driving instead originates from information processing and erasure? The result is a fluid comprised of microscopic controllers carrying out feedback loops that can use environmental noise as a source of motive power. We demonstrate how such a system, when simulated, can create patterns that are immune to noise. Furthermore, actions taken because of local measurements can drive global spontaneous symmetry breaking. We discuss the informational origin of the thermodynamic driving force behind such behaviors with a Markov Chain model, as well as develop a kinetic theory of the controller gas in the thermal setting that highlights the connection between symmetries of agent behavior and macroscopic properties. These connections are robust enough to explain controller gas behavior even when the noisy environmental fluctuations do not follow a thermal distribution. This work explores a model system that highlights the informational aspect of recent feedback-controlled colloidal active matter and biological experiments.