Quantum coherence and the invisible Universe: Subradiance as a dark matter mechanism

TL;DR

This paper proposes that quantum coherence and entanglement among atomic hydrogen in galactic halos can cause subradiance, making the gas effectively dark and transparent, potentially explaining dark matter.

Contribution

It introduces a quantum mechanical mechanism involving Dicke states that could account for dark matter properties in galactic halos.

Findings

Hydrogen gas can naturally exhibit subradiance at thermal equilibrium.

Conditions in galactic halos place hydrogen in the subradiance regime, suppressing emission.

High-velocity clouds' properties are consistent with this quantum dark matter model.

Abstract

The origin of dark matter in galactic halos, one of the deepest unsolved problems in astrophysics, may find an unexpected contribution from the quantum mechanics of ordinary atomic hydrogen. We show that quantum entanglement and coherence among hydrogen atoms in a gas at thermal equilibrium can naturally lead to subradiance, a cooperative suppression of radiation that renders the gas simultaneously dark in emission, transparent to incident radiation, and effectively collision-less. These three properties, precisely those associated with dark matter, emerge from a single underlying physical mechanism: the entangled structure of Dicke states in the gas. Applying this framework to the 21 cm line of atomic hydrogen in galactic dark matter halos, we find that conditions there place the gas deep in the asymptotic subradiance regime, where the strongly suppressed spontaneous and stimulated intensities cancel exactly. The cold neutral cores of high-velocity clouds, with their observed temperatures near 100 K and inferred dark-to-visible mass ratios of ~100:1, are consistent with this picture. Our results suggest that a significant fraction of the non-luminous matter pervading galactic halos may be familiar atomic hydrogen whose quantum cooperative behavior hides it from view; a solution that may have been hiding in plain sight.