In situ observation of strongly interacting ferromagnetic domains in a shaken optical lattice
In situ observation of strongly interacting ferromagnetic domains in a shaken optical lattice
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原位观察振动光学晶格中强相互作用的铁磁畴
DOI：
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发表时间：
2013
期刊：
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通讯作者：
C. Chin
中科院分区：
文献类型：
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作者：
C. Parker;Li;C. Chin
固态系统的丰富性来自于粒子间相互作用和偏离自由粒子的新型能带结构之间的相互作用。在强相互作用的系统中，这两种现象同等重要，表现出各种理论上有趣和实际有用的阶段。超冷原子系统正迅速成为精确和可控的模拟器，而正是在这种强相互作用的状态下，模拟是最有用的。在这里，我们演示了如何在光学晶格中杂化布洛赫带，以在流动原子系统中引入长程铁磁有序。我们发现具有双阱色散的玻色子的自发对称性破缺凝聚成两个不同的极小值之一，我们用自旋向上和自旋向下来识别。快速淬火到铁磁态后的密度动力学证实了两态之间的量子干涉是对称破缺的机制。与旋量凝聚体不同，在旋量凝聚体中，相互作用是由散射长度的小自旋相关差异驱动的，我们的相互作用与散射长度本身有关，导致快速平衡并发展出强相互作用铁磁体特征的尖锐边界的域。
Solid state systems derive their richness from the interplay between interparticle interactions and novel band structures that deviate from those of free particles. Strongly interacting systems, where both of these phenomena are of equal importance, exhibit a variety of theoretically interesting and practically useful phases. Systems of ultracold atoms are rapidly emerging as precise and controllable simulators, and it is precisely in this strongly interacting regime where simulation is the most useful. Here we demonstrate how to hybridize Bloch bands in optical lattices to introduce long-range ferromagnetic order in an itinerant atomic system. We find spontaneously broken symmetry for bosons with a double-well dispersion condensing into one of two distinct minima, which we identify with spin-up and spin-down. The density dynamics following a rapid quench to the ferromagnetic state confirm quantum interference between the two states as the mechanism for symmetry breaking. Unlike spinor condensates, where interaction is driven by small spin-dependent differences in scattering length, our interactions scale with the scattering length itself, leading to domains which equilibrate rapidly and develop sharp boundaries characteristic of a strongly interacting ferromagnet.