High-Efficiency Three-Stroke Quantum Isochoric Heat Engine: From Infinite Potential Wells to Magic Angle Twisted Bilayer Graphene

TL;DR

This paper presents a highly efficient three-stroke quantum heat engine cycle, implemented in various graphene systems, notably achieving maximum efficiency in magic-angle twisted bilayer graphene, with implications for nanoscale thermodynamics.

Contribution

It introduces a novel three-stroke quantum isochoric cycle that outperforms classical and other quantum cycles, and demonstrates its implementation in graphene-based systems, especially at magic angles.

Findings

Quantum cycle surpasses classical engine efficiencies.

Magic-angle twisted bilayer graphene achieves highest efficiency.

Reduced stroke number simplifies nanoscale device control.

Abstract

We introduce a three-stroke quantum isochoric cycle that functions as a heat engine operating between two thermal reservoirs. Implemented for a particle confined in a one-dimensional infinite potential well, the cycle's performance is benchmarked against the classical three-stroke triangular and isochoric engines. We find that the quantum isochoric cycle achieves a higher efficiency than both classical counterparts and also surpasses the efficiency of the recently proposed three-stroke quantum isoenergetic cycle. Owing to its reduced number of strokes, the design substantially lowers control complexity in nanoscale thermodynamic devices, offering a more feasible route to experimental realization compared to conventional four-stroke architectures. We further evaluate the cycle in graphene-based systems under an external magnetic field, including monolayer graphene (MLG), AB-stacked bilayer graphene (BLG), and twisted bilayer graphene (TBG) at both magic and non-magic twist angles. Among these platforms, magic-angle twisted bilayer graphene (MATBG) attains the highest efficiency at fixed work output, highlighting its promise for quantum thermodynamic applications.