Long-lived phantom helix states in Heisenberg quantum magnets
Long-lived phantom helix states in Heisenberg quantum magnets
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DOI：
10.1038/s41567-022-01651-7
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发表时间：
2022-07-14
期刊：
影响因子：
19.6
通讯作者：
Ketterle, Wolfgang
中科院分区：
文献类型：
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作者：
Jepsen, Paul Niklas;Lee, Yoo Kyung 'Eunice';Ketterle, Wolfgang
在一般的量子多体系统中，远离平衡态的初始构型预计会经历一般的热化。一个超冷原子的实验现在显示了一类自旋-螺旋态的证据，这些态可以避免这种行为。量子多体系统的精确解是罕见的，但它为描述宇宙现象提供了有价值的见解，例如强相互作用系统的非平衡动力学和量子物质新形式的表征。最近，可积自旋模型的Bethe平衡方程的特殊解被发现，它们被称为Phantom Bethe态，可以携带宏观动量而没有能量。在这里，我们的实验表明，存在特殊的螺旋自旋模式的各向异性海森堡链是长寿命的，放松只有非常缓慢的动力学，作为这种状态的后果。我们使用这些幻影自旋螺旋状态，直接测量的相互作用各向异性，这有一个主要的贡献，从短程场外相互作用。我们还将理论描述推广到更高的维度和其他不可积系统，并找到类似的稳定自旋螺旋，这应该显示与所谓的量子多体疤痕相关的非热化动力学。这些结果对自旋物理的量子模拟以及多体动力学都有意义。
In generic quantum many-body systems, initial configurations far from equilibrium are expected to undergo general thermalization. An experiment with ultracold atoms now shows evidence of a class of spin-helix states that evade such behaviour.Exact solutions for quantum many-body systems are rare but provide valuable insights for the description of universal phenomena such as the non-equilibrium dynamics of strongly interacting systems and the characterization of new forms of quantum matter. Recently, specific solutions of the Bethe ansatz equations for integrable spin models were found. They are dubbed phantom Bethe states and can carry macroscopic momentum yet no energy. Here, we show experimentally that there exist special helical spin patterns in anisotropic Heisenberg chains which are long-lived, relaxing only very slowly in dynamics, as a consequence of such states. We use these phantom spin-helix states to directly measure the interaction anisotropy, which has a major contribution from short-range off-site interactions. We also generalize the theoretical description to higher dimensions and other non-integrable systems and find analogous stable spin helices, which should show non-thermalizing dynamics associated with so-called quantum many-body scars. These results have implications for the quantum simulation of spin physics, as well as many-body dynamics.