An invitation to Quantum Thermodynamics

Thermodynamics consolidated itself during the Industrial Revolution, establishing a theoretical and practical framework to describe how energy can be transformed and used. The advent of Information Theory drew one of the first connections between information and energy, leading to the reformulation of several thermodynamic concepts from this perspective. Quantum Thermodynamics then emerges from the need to describe energy exchanges in systems governed by the laws of Quantum Mechanics. The second quantum revolution further drives this scenario, in which technologies are increasingly miniaturized, making it essential to understand the role of quantum laws for optimized devices. In this article, we revisit the ideas that gave rise to Quantum Thermodynamics and present an introduction to its theoretical foundations. We discuss the definitions of work, heat, and entropy in quantum systems, reinterpret the first and second laws in this context, and illustrate these concepts through the example of a single-qubit system. We also explore how quantum resources can provide thermodynamic advantages. Next, we address two central applications: thermal machines and quantum batteries, discussing their theoretical models and experimental implementations. We conclude by highlighting the current challenges and the potential advances in this rapidly growing field. Our aim is to offer a concise introduction to the field for undergraduate and graduate students from different STEM backgrounds.

Keywords
Quantum information; quantum thermodynamics; quantum technologies