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arXiv · 2605.23528

Vacuum-Triggered Instability in Paired Superradiance

Zhan Bai·Ningqiang Song·Min Chen·Xiangyan An·Baifei Shen·Liangliang Ji·Ruxin Li
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Abstract

Paired superradiance (PSR) is a macro-coherent two-photon process capable of very large gain, making it promising for detecting ultra-weak signals induced by neutrinos or dark matter. A major goal has been to increase the system volume $V$ and density $n$, since the signal intensity scales as $(nV)^2$. We recast finite PSR as a parametric amplifier driven by the electromagnetic vacuum. The usual zero-field semiclassical initial condition is replaced by vacuum inputs fixed by the quantum two-point function. Combining this formulation with Maxwell--Bloch evolution and finite-length stability analysis, we find that PSR produces an irreducible vacuum background that can develop into macroscopic bursts once the gain-length product exceeds \(\Gamma L=\pi/2\) for a sufficient coherence time. These results, together with a closed-form formula for estimating the vacuum-seeded photon yield, establish a previously overlooked constraint for high-gain PSR, with direct implications for proposed neutrino and dark-matter studies.

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Zhan Bai, Ningqiang Song, Min Chen, Xiangyan An, Baifei Shen, Liangliang Ji, Ruxin Li. 2026-05-22. Vacuum-Triggered Instability in Paired Superradiance. https://arxiv.org/abs/2605.23528

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