Rydow Erik, Singh Vijay Pal, Beregi Abel, Chang En, Mathey Ludwig, Foot Christopher J, Sunami Shinichi
Clarendon Laboratory, University of Oxford, Oxford, United Kingdom.
Quantum Research Centre, Technology Innovation Institute, Abu Dhabi, UAE.
Nat Commun. 2025 Aug 5;16(1):7201. doi: 10.1038/s41467-025-62277-w.
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.
控制多体系统中不同自由度之间的耦合是一种用于构建新型物质相的强大技术。我们创建了一个二维（2D）超冷玻色气体的双层系统，并通过可调谐的层间约瑟夫森耦合展示了体相干的可控生成。我们探测了双层系统两种相位模式的相关特性：对称相位模式通过噪声相关方法进行研究，而非对称相位涨落则通过物质波干涉测量法直接捕获。这两种模式的测量相关函数在一个依赖于耦合的临界点之上均表现出从短程到准长程有序的转变，从而为层间耦合介导的双层超流性提供了直接证据。我们绘制出相图，并用重整化群理论和蒙特卡罗模拟对其进行解释。此外，我们通过观察非对称模式中受抑制的涡旋激发来阐明其潜在机制。
