Van der Waals Anomaly

TL;DR

This paper reveals a van der Waals anomaly in inhomogeneous media where the usual stress-divergence relationship is violated, and proposes an experiment with ultracold atoms to explore this quantum anomaly and its analogy to dark energy.

Contribution

It identifies a novel van der Waals anomaly arising from renormalization in electromagnetic vacuum forces and suggests an experimental test using ultracold atoms.

Findings

Discovered anomalous pressure in electromagnetic vacuum forces.

Linked the anomaly to renormalization and subtraction of infinities.

Proposed an experimental setup to observe the effect.

Abstract

In inhomogeneous dielectric media the divergence of the electromagnetic stress is related to the gradients of \varepsilon and \mu, which is a consequence of Maxwell's equations. Investigating spherically symmetric media we show that this seemingly universal relationship is violated for electromagnetic vacuum forces such as the generalized van der Waals and Casimir forces. The stress needs to acquire an additional anomalous pressure. The anomaly is a result of renormalization, the need to subtract infinities in the stress for getting a finite, physical force. The anomalous pressure appears in the stress in media like dark energy appears in the energy-momentum tensor in general relativity. We propose and analyse an experiment to probe the van der Waals anomaly with ultracold atoms. The experiment may not only test an unusual phenomenon of quantum forces, but also an analogue of dark energy, shedding light where nothing is known empirically.