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arXiv · 2610.20897

Casimir Sign Reversal from Finite-Range Bogoliubov Fluctuations

Fabrizio Canfora·Pablo Pais·Luigi Rosa
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Abstract

We study the zero-temperature Casimir effect of a three-dimensional Bose fluid with finite-range corrections to its Bogoliubov spectrum. Beyond the universal acoustic contribution scaling as $L^{-3}$, the long-distance expansion contains a nonuniversal $L^{-5}$ correction that can compete with the phononic term. We derive this crossover analytically within a minimal isotropic finite-range model and test the asymptotic result against the full dispersion. A regulator-independent Poisson-resummed calculation confirms that sign reversals of the Casimir energy are possible, while showing that the apparent low-coupling zero inferred by balancing only the $L^{-3}$ and $L^{-5}$ terms is not quantitatively controlled. Robust sign changes instead occur in the stable regime close to roton softening, where the Casimir energy acquires an oscillatory finite-momentum contribution. Strongly dipolar atomic gases provide a natural motivation for microscopic interaction lengths in the nanometric regime. We further discuss how the resulting nonlinear force law could be probed through the frequency response of a driven nanomechanical resonator.

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Fabrizio Canfora, Pablo Pais, Luigi Rosa. 2026-10-14. Casimir Sign Reversal from Finite-Range Bogoliubov Fluctuations. https://arxiv.org/abs/2610.20897

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