Thermodynamics of genuine non-equilibrium states under feedback control

TL;DR

This paper extends the Hatano-Sasa equality to genuine non-equilibrium states with feedback control, providing sharper bounds on work extraction and showing that power can surpass driving costs in certain conditions.

Contribution

It introduces a new theoretical framework for non-equilibrium states under feedback, improving bounds on work extraction beyond previous equalities.

Findings

Extended Hatano-Sasa equality for feedback-controlled non-equilibrium states

Derived sharper bounds on maximal extractable work

Demonstrated power exceeding driving cost in a solvable example

Abstract

For genuine non-equilibrium states that even at fixed external control parameter exhibit dissipation, we extend the Hatano-Sasa equality to processes with feedback control. The resulting bound on the maximal extractable work is substantially sharper than what would follow from applying the Sagawa-Ueda equality to transitions involving such states. For repeated measurements at short enough intervals, the power thus extracted can even exceed the average cost of driving as demonstrated explicitly with a simple, analytically solvable example.