Quantum critical behaviour at the many-body localization transition
Quantum critical behaviour at the many-body localization transition
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DOI：
10.1038/s41586-019-1527-2
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发表时间：
2018-12
期刊：
影响因子：
64.8
通讯作者：
M. Rispoli;A. Lukin;R. Schittko;Sooshin Kim;M. Tai;J. Léonard;M. Greiner
中科院分区：
文献类型：
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作者：
M. Rispoli;A. Lukin;R. Schittko;Sooshin Kim;M. Tai;J. Léonard;M. Greiner
相变是由一个系统的成分在临界点出现的集体波动驱动的。这一机制已被广泛探讨的经典和量子系统的平衡，其临界行为所描述的相变的一般理论。然而，最近，已经发现了从根本上不同的相变的非平衡量子系统，它可以表现出临界行为，违背了这一描述，并没有得到很好的理解。一个典型的例子是多体局域化（MBL）跃迁，它标志着一个孤立的量子多体系统中的热化的崩溃，因为它的无序度超过了临界值，-。表征MBL系统中的量子临界行为需要探测其在空间和时间上的纠缠，由于对量子态制备和系统隔离的严格要求，这在实验上已被证明具有挑战性。在这里，我们观察到量子临界行为的MBL过渡在无序玻色-哈伯德系统和表征其纠缠通过其多点量子关联。我们观察到强相关性的出现，伴随着整个系统的异常扩散运输的发病，并通过测量它们对系统大小的依赖性来验证它们的临界性质。相关性延伸到量子临界状态的高阶，并且似乎通过跨越整个系统的多体共振的稀疏网络形成。我们的研究结果连接的宏观现象的过渡到系统的微观结构的量子相关性，他们提供了一个重要的一步，了解临界性和普遍性的非平衡系统，。
Phase transitions are driven by collective fluctuations of a system’s constituents that emerge at a critical point. This mechanism has been extensively explored for classical and quantum systems in equilibrium, whose critical behaviour is described by the general theory of phase transitions. Recently, however, fundamentally distinct phase transitions have been discovered for out-of-equilibrium quantum systems, which can exhibit critical behaviour that defies this description and is not well understood. A paradigmatic example is the many-body localization (MBL) transition, which marks the breakdown of thermalization in an isolated quantum many-body system as its disorder increases beyond a critical value, , , , , , , , –. Characterizing quantum critical behaviour in an MBL system requires probing its entanglement over space and time,,, which has proved experimentally challenging owing to stringent requirements on quantum state preparation and system isolation. Here we observe quantum critical behaviour at the MBL transition in a disordered Bose–Hubbard system and characterize its entanglement via its multi-point quantum correlations. We observe the emergence of strong correlations, accompanied by the onset of anomalous diffusive transport throughout the system, and verify their critical nature by measuring their dependence on the system size. The correlations extend to high orders in the quantum critical regime and appear to form via a sparse network of many-body resonances that spans the entire system,. Our results connect the macroscopic phenomenology of the transition to the system’s microscopic structure of quantum correlations, and they provide an essential step towards understanding criticality and universality in non-equilibrium systems,,.