Open Problems on Information and Feedback Controlled Systems

TL;DR

This paper reviews the current understanding and open problems in the thermodynamics of feedback-controlled systems, emphasizing the role of information theory and the challenges in establishing comprehensive formal frameworks.

Contribution

It highlights the main open problems in the thermodynamics of feedback systems, including issues of redundancy, continuous operation, and implications for nanotechnology and biological systems.

Findings

Identifies key open problems in feedback thermodynamics.

Discusses the importance of information theory in system performance.

Highlights the need for complete formal answers to advance the field.

Abstract

Feedback or closed-loop control allows dynamical systems to increase their performance up to a limit imposed by the second law of thermodynamics. It is expected that within this limit, the system performance increases as the controller uses more information about the system. However, despite the relevant progresses made recently, a general and complete formal development to justify this statement using information theory is still lacking. We present here the state-of-the-art and the main open problems that include aspects of the redundancy of correlated operations of feedback control and the continuous operation of feedback control. Complete answers to these questions are required to firmly establish the thermodynamics of feedback controlled systems. Other relevant open questions concern the implications of the theoretical results for the limitations in the performance of feedback controlled flashing ratchets, and for the operation and performance of nanotechnology devices and biological systems.