Extracting work from a single heat bath - A case study on Brownian particle under external magnetic field in presence of information

TL;DR

This paper investigates how work can be extracted from a single heat bath using measurement and information, focusing on a Brownian particle under magnetic field, and finds that magnetic fields influence the work extraction process.

Contribution

It provides explicit optimal protocols for work extraction in a Brownian system under magnetic field, revealing the magnetic field's effect on work and protocols.

Findings

Optimal protocols depend on the magnetic field.

Work extraction is independent of magnetic field in one case.

Magnetic field reduces the amount of work that can be extracted.

Abstract

Work can be extracted from a single bath beyond the limit set by the second law by performing measurement on the system and utilising the acquired information. As an example we studied a Brownian particle confined in a two dimensional harmonic trap in presence of magnetic field, whose position co-ordinates are measured with finite precision. Two separate cases are investigated in this study - (A) moving the center of the potential and (B) varying the stiffness of the potential. Optimal protocols which extremise the work in a finite time process are explicitly calculated for these two cases. For Case-A, we show that even though the optimal protocols depend on magnetic field, surprisingly, extracted work is independent of the field. For Case-B, both the optimal protocol and the extracted work depend on the magnetic field. However, the presence of magnetic field always reduces the extraction of work.