Negative thermodynamic pressure: no-go theorem and yes-go examples

TL;DR

This paper investigates the microscopic origins of negative thermodynamic pressure states using quantum thermodynamics, establishing a no-go theorem for boundary-exerted pressure and providing examples where negative pressure occurs due to boundary coupling.

Contribution

It introduces a no-go theorem proving positive boundary pressure in quantum states without boundary interaction and offers examples of stable negative pressure states via boundary coupling.

Findings

Boundary pressure is positive without boundary interaction.

Negative pressure states can exist with specific boundary couplings.

A general formula for quantum non-equilibrium pressure is derived.

Abstract

Theory and experiment have long discussed negative thermodynamic pressure states, but their microscopic origins are unclear. I address this problem within the framework of quantum thermodynamics. I show that the pressure exerted on the boundary is positive when there is no interaction with the boundary. This is formalized by a no-go theorem that holds for any quantum state with finite motion. As a consequence of this analysis, I deduce a general formula for quantum non-equilibrium pressure. It is believed that stable negative pressure states cannot exist in gases. I provide solvable examples of quantum and classical gases, where negative pressure is achieved due to a suitable coupling with the boundary walls.