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Entropy and the Second Law of Thermodynamics

Entropy and the Second Law of Thermodynamics

The second law of thermodynamics can be stated quantitatively using the concept of entropy. Entropy is the measure of disorder of the system.
The relation between entropy and disorder can be illustrated with the example of the phase change of ice to water. In ice, the molecules are located at specific sites giving a solid state, whereas, in a liquid form, these molecules are much freer to move. The molecular arrangement has therefore become more randomized. Although the change in average...

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In the quest to identify a property that may reliably predict the spontaneity of a process, a promising candidate has been identified: entropy. Processes that involve an increase in entropy of the system (ΔS > 0) are very often spontaneous; however, examples to the contrary are plentiful. By expanding consideration of entropy changes to include the surroundings, a significant conclusion regarding the relation between this property and spontaneity may be reached. In thermodynamic...

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A Photonic System for Generating Unconditional Polarization-Entangled Photons Based on Multiple Quantum Interference

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Quantum and Classical Ergotropy from Relative Entropies.

Akira Sone^1,2,3, Sebastian Deffner^4,5

¹Aliro Technologies, Inc., Boston, MA 02135, USA.

Entropy (Basel, Switzerland)

|September 28, 2021

Summary

This study introduces classical ergotropy, measuring extractable work from inhomogeneous distributions. It unifies quantum and classical work extraction via geometric quantum mechanics, enhancing the maximum work theorem.

Keywords:

conditional thermal state ergotropy geometric quantum mechanics

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Area of Science:

Quantum thermodynamics
Statistical mechanics
Geometric quantum mechanics

Background:

Quantum ergotropy quantifies maximal work from quantum states without entropy change.
Ergotropy relates to quantum and classical relative entropies compared to thermal states.

Purpose of the Study:

Define classical ergotropy for inhomogeneous distributions.
Develop a unified framework for quantum and classical work extraction.
Apply insights to conditional thermal states and the maximum work theorem.

Main Methods:

Defining classical ergotropy based on relative entropies.
Utilizing geometric quantum mechanics for a unified approach.
Introducing geometric relative entropy.

Main Results:

Classical ergotropy quantifies work from inhomogeneous distributions.
Geometric quantum mechanics provides a unified framework.
The maximum work theorem is refined for conditional thermal states.

Conclusions:

The concept of classical ergotropy extends work extraction principles.
Geometric quantum mechanics offers a powerful unified perspective.
Refined maximum work theorems have implications for quantum thermodynamics.