# Stochastic thermodynamics with arbitrary interventions

## TL;DR

This paper generalizes stochastic thermodynamics to include discrete, imperfect measurements and arbitrary manipulations, providing a comprehensive framework for analyzing thermodynamic quantities along trajectories with feedback and incomplete information.

## Contribution

It introduces a unified theory of stochastic thermodynamics accommodating arbitrary interventions, measurements, and incomplete information, extending previous continuous and perfect measurement models.

## Key findings

- Verified the first and second laws at the trajectory level.
- Derived a general inequality for free energy differences in Jarzynski experiments.
- Analyzed a Maxwell demon experiment with real-time feedback control.

## Abstract

We extend the theory of stochastic thermodynamics in three directions: (i) instead of a continuously monitored system we consider measurements only at an arbitrary set of discrete times, (ii) we allow for imperfect measurements and incomplete information in the description, and (iii) we treat arbitrary manipulations (e.g. feedback control operations) which are allowed to depend on the entire measurement record. For this purpose we define for a driven system in contact with a single heat bath the four key thermodynamic quantities: internal energy, heat, work and entropy along a single `trajectory' for a causal model. The first law at the trajectory level and the second law on average is verified. We highlight the special case of Bayesian or `bare' measurements (incomplete information, but no average disturbance) which allows us to compare our theory with the literature and to derive a general inequality for the estimated free energy difference in Jarzynksi-type experiments. An analysis of a recent Maxwell demon experiment using real-time feedback control is also given. As a mathematical tool, we prove a classical version of Stinespring's dilation theorem, which might be of independent interest.