Quantum simulators built from ultracold atoms promise to study quantum phenomena in interacting many-body systems. However, it remains a challenge to experimentally prepare strongly correlated continuous systems such that the properties are dominated by quantum fluctuations. Here, we show how to enhance the quantum correlations in a one-dimensional multimode bosonic Josephson junction, which is a quantum simulator of the sine-Gordon field theory. Our approach is based on the ability to track the nonequilibrium dynamics of quantum properties. After creating a bosonic Josephson junction at the stable fixed point of the classical phase space, we observe squeezing oscillations in the two conjugate variables. We show that the squeezing oscillation frequency can be tuned by more than one order of magnitude, and we are able to achieve a spin squeezing close to 10 dB by utilizing these oscillatory dynamics. The impact of improved spin squeezing is directly revealed by detecting enhanced spatial phase correlations between decoupled condensates. Our work provides new ways for engineering correlations and entanglement in the external degree of freedom of interacting many-body systems.

中文翻译：

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多模玻色约瑟夫森结中的压缩振荡

由超冷原子构建的量子模拟器有望研究相互作用的多体系统中的量子现象。然而，通过实验制备强相关连续系统，使其特性由量子涨落主导，仍然是一个挑战。在这里，我们展示了如何增强一维多模玻色约瑟夫森结中的量子相关性，这是正弦戈登场论的量子模拟器。我们的方法基于跟踪量子特性的非平衡动力学的能力。在经典相空间的稳定不动点处创建玻色约瑟夫森结后，我们观察到两个共轭变量的挤压振荡。我们表明，挤压振荡频率可以调整一个以上数量级，并且利用这些振荡动力学，我们能够实现接近 10 dB 的自旋挤压。通过检测解耦凝聚体之间增强的空间相位相关性，可以直接揭示改进的自旋挤压的影响。我们的工作为交互多体系统外部自由度的工程关联和纠缠提供了新的方法。