Quantum Collapse and the Second Law of Thermodynamics

TL;DR

This paper explores how quantum effects can enhance heat engine efficiency but also generate entropy through wavefunction collapse, linking quantum measurement to the second law of thermodynamics and suggesting potential violations if collapse isn't inherently random.

Contribution

It provides a quantitative analysis of the trade-off between quantum efficiency gains and entropy production, connecting quantum measurement postulates to thermodynamic laws.

Findings

Quantum superpositions can improve engine efficiency.

Wavefunction collapse generates excess entropy.

Inherent randomness of collapse is crucial to uphold the second law.

Abstract

A heat engine undergoes a cyclic operation while in equilibrium with the net result of conversion of heat into work. Quantum effects such as superposition of states can improve an engine's efficiency by breaking detailed balance, but this improvement comes at a cost due to excess entropy generated from collapse of superpositions on measurement. We quantify these competing facets for a quantum ratchet comprised of an ensemble of pairs of interacting two-level atoms. We suggest that the measurement postulate of quantum mechanics is intricately connected to the second law of thermodynamics. More precisely, if quantum collapse is not inherently random, then the second law of thermodynamics can be violated. Our results challenge the conventional approach of simply quantifying quantum correlations as a thermodynamic work deficit.