Informational work storage in quantum thermodynamics

TL;DR

This paper explores informational work storage in quantum thermodynamics, proposing a model based on maximally mixed qubits that better aligns with thermodynamic principles than traditional mechanical models.

Contribution

It introduces an informational work storage concept using maximally mixed qubits, addressing issues with quantum weight models and clarifying work extraction limits.

Findings

Maximal extractable work is scheme-independent, consistent with the second law.

The informational storage model avoids acting as an entropy sink.

The approach distinguishes work from heat in quantum systems.

Abstract

We present a critical examination of the difficulties with the quantum versions of a lifted weight that are widely used as work storage systems in quantum thermodynamics. To overcome those difficulties, we turn to the strong connections between information and thermodynamics illuminated by Szilard's engine and Landauer's principle, and consider the concept of informational work storage. This concept is in sharp contrast with the usual one of mechanical work storage underlying the idealization of a quantum weight. An informational work storage system based on maximally mixed qubits that does not act as an entropy sink and is capable of truly distinguishing work from heat is studied. Applying it to the problem of single-shot work extraction in various extraction schemes, we show that for a given system state the maximum extractable work is independent of extraction scheme, in accordance with the second law of thermodynamics.