Tunable Anomalous Diffusion in Subrecoil-Laser-Cooled Atoms

Abstract

Laser cooling of atomic motion enables advances in quantum information and precision metrology. However, the spatial spreading of subrecoil-laser-cooled atoms---crucial for understanding cooling mechanisms and atomic confinement---remains largely unexplored. Here, we analyze anomalous diffusion in subrecoil-laser-cooled atoms, where a velocity-dependent fluorescence rate $R(v) \propto |v|^{\alpha}$ governs transport properties. By tuning $\alpha$, we uncover transitions between normal, subdiffusive, and superdiffusive regimes. Notably, at $\alpha = 3/2$, diffusion is minimized, leading to optimal atomic confinement. We further identify a conceptual link between subrecoil laser cooling and the Pomeau-Manneville map from nonlinear dynamics, revealing that anomalous diffusion can generically exhibit a nontrivial minimum in spatial spreading---even across seemingly unrelated physical systems.