Quantum Phase Space Approach to the Ideal Fermi and Bose Gases

TL;DR

This paper introduces quantum phase space-based models for ideal Fermi and Bose gases, incorporating quantum uncertainty to improve thermodynamic predictions, especially at low temperatures and confined geometries.

Contribution

The work develops new models of quantum gases using quantum phase space, providing analytic thermodynamic expressions that include quantum corrections and recover classical limits.

Findings

Quantum corrections are significant at low temperatures.

Derived thermodynamic quantities include entropy and pressure.

Models recover classical relations at high temperatures.

Abstract

In this work, improvements are introduced to the current models of the ideal Fermi gas and the ideal Bose gas by incorporating the quantum nature of phase space, which is directly linked to the uncertainty principle. These improved models build upon the recently developed concepts of quantum phase space (QPS) and the QPS representation of quantum mechanics. The Hamiltonian operator for a gas particle and its eigenstates are first determined, and quantum statistical mechanics is used to derive the thermodynamic properties of the ideal gas. Analytic expressions for thermodynamic quantities—including the grand canonical potential, particle number, internal energy, von Neumann entropy, and pressure—are derived, along with the corresponding thermodynamic equations of state for both bosons and fermions. These corrections are particularly significant at low temperatures and in confined volumes, where quantum effects related to system geometry, such as shape and size, become significant. The results also establish a direct link between thermodynamic functions and the quantum statistical variances of momentum. Importantly, the improved models recover well-known classical relations of the ideal gas in the high-temperature and large-volume limits, ensuring consistency with classical physics. By addressing quantum corrections and their thermodynamic implications, this work provides a foundation for further applications in nanoscale systems, quantum gases, low-temperature physics, ultracold physics, and astrophysics.