Quantum Thermodynamics of Non-Ideal Gases

TL;DR

This paper develops a quantum framework for thermodynamics of non-ideal gases, revealing quantum fluctuations in pressure and volume when the thermal wavelength is comparable to the system size, and introduces a thermodynamic wave function.

Contribution

It extends quantum thermodynamics to non-ideal gases by deriving a wave equation and solutions, connecting quantum fluctuations with molecular properties.

Findings

Quantum fluctuations in thermodynamic variables are significant at small scales.

A wave equation for thermodynamics of van der Waals gases is derived.

Coherent states approximate classical thermodynamic behavior.

Abstract

We show that when the thermal wavelength is comparable to the spatial size of a system, thermodynamic observables like Pressure and Volume have quantum fluctuations that cannot be ignored. They are now represented by operators; conventional (classical) thermodynamics is no longer applicable. We continue the work in earlier papers where quantization rules for thermodynamics were developed by analogy with optics and mechanics, by working out explicitly the quantum theory of van der Waals gases. We find a wave equation satisfied by the thermodynamic wave function as well as solutions ({\em coherent states}) that are centered at the classical equations of state. The probability of departure from the classical theory is dependent on a parameter $\sigma$ which is a property of the gas molecule.