2025-09-16 オックスフォード大学
A red glowing cloud of rubidium atoms visible in the Ultracold Quantum Matter group’s experiment. Credit: Erik Rydow, Ultracold Quantum Matter group.
＜関連情報＞
- https://www.ox.ac.uk/news/features/opening-window-quantum-world
- https://www.nature.com/articles/s41467-025-62277-w
層間コヒーレンスを有する二層系超流動体の観測 Observation of a bilayer superfluid with interlayer coherence
Erik Rydow,Vijay Pal Singh,Abel Beregi,En Chang,Ludwig Mathey,Christopher J. Foot & Shinichi Sunami
Nature Communications Published:05 August 2025
DOI:https://doi.org/10.1038/s41467-025-62277-w
Abstract
Controlling the coupling between different degrees of freedom in many-body systems is a powerful technique for engineering novel phases of matter. We create a bilayer system of two-dimensional (2D) ultracold Bose gases and demonstrate the controlled generation of bulk coherence through tunable interlayer Josephson coupling. We probe the resulting correlation properties of both phase modes of the bilayer system: the symmetric phase mode is studied via a noise-correlation method, while the antisymmetric phase fluctuations are directly captured by matter-wave interferometry. The measured correlation functions for both of these modes exhibit a crossover from short-range to quasi-long-range order above a coupling-dependent critical point, thus providing direct evidence of bilayer superfluidity mediated by interlayer coupling. We map out the phase diagram and interpret it with renormalization-group theory and Monte Carlo simulations. Additionally, we elucidate the underlying mechanism through the observation of suppressed vortex excitations in the antisymmetric mode.
